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Assessing the role of branched- chain amino acids metabolism in soybean responses to drought stressCatalina BarbotVidal, S. (1); Castro, A (1).; Ibañez, F.(2)(1) Facultad de ciencias, UDELAR, Uruguay. (2) Instituto Nacional de Investigación Agropecuaria, Uruguay.Water deficit is one of the major stress factors that affect soybean productivity and quality. Plants employ a variety of response mechanisms to cope with adverse environmental conditions. One of the most general responses to abiotic stress is metabolic reprogramming, including the accumulation of amino acids such as proline and branched chain amino acids (BCAA). We have analyzed BCAA levels in soybean genotypes exhibiting contrasting phenotypes to drought stress. We found that all soybean lines accumulate high levels of BCAAs under drought conditions. Moreover, drought tolerant slow wilting lines accumulate higher levels of BCAAs in response to water deficit than fast wilting genotypes, which supports the role of this type of responses in drought tolerance. Changes in BCAAs levels appear to be associated with the expression of branched-chain amino acid transferases (BCAT) that participate in their synthesis and degradation. The anabolic or catabolic activity of BCATs seems to be associated with its subcellular localization. In this study, we aim to functionally characterize a drought induced soybean gene (GmDIAAT-Glycine max Drought Induced Amino Acid Transferase), which shares sequence similarity to BCATs. To determine the subcellular localization of the enzyme, transgenic Arabidopsis thaliana lines overexpressing GmDIAAT-GFP have been generated and visualized by confocal microscopy. To assess the role of GmDIAAT in BCAAs abiotic stress tolerance, we generated transgenic Arabidopsis thaliana lines overexpressing GmDIAAT and analyzed the phenotype of these lines under different stress conditions. Finally, BCAA content will be monitored in GmDIAAT overexpressing lines to assess the role of this gene in BCAAs metabolism. Together, these results will contribute to understand the role of BCAAs in abiotic stress tolerance in soybean and to design strategies to increase drought tolerance through the modulation of BCAA metabolism in soybean.Soybean, drought, metabolism
Evaluation of the effect of livestock density on the vegetation of wetlands of the Middle Paraná RiverTREISSE, IRINASABATTINI J., LORENTE C., BERÓN C., MESA L.Instituto Nacional de Limnología (INALI)Summary: During the last decades, the expansion of the agricultural frontier led to a displacement of livestock towards regions with little aptitude for agriculture, such as wetlands. The excessive increase in this activity without quantification and management guidelines cause an environmental and social problem. The livestock stocking rate influences the structure of vegetation community, producing positive or negative effects. The aim of this work was to assess the effect of livestock stocking rate on vegetation in wetlands of the middle Paraná river. Sampling were conducted in five sites under continuous grazing with high (greater than 1 EV ha-1) and low stocking rate (less than 1 EV ha-1) in November 2021 and March 2022. Four square (size of 4 m2) were used to estimate the herbaceous vegetation cover in two areas depending on topographic position (lowland and upland vegetation). Species were classified as forage, non-forage, and toxic to livestock. Shannon-Weaver diversity (H') and forage/non-forage ratio were calculated. Nonparametric analyzes (Mann-Whitney and NMDS) were performed between high or low livestock stocking rate. In general, significant differences were observed in forage cover and in “forage/non-forage” ratio (p<0.05), with a higher mean value in low livestock stocking rate. In lowland vegetation, the total diversity was higher in low livestock stocking rate while in upland there no significative differences (p<0.05). In the NMDS analysis, groupings of sites were observed according to topographic position and livestock stocking rate. Species of the genus Polygonum sp. were associated with high stocking rate sites and Louisiella elephantipes to low stocking rate. In drier periods of low water availability, lowland vegetation maintains a greater coverage of forage species. In this regard, the effect of livestock stocking rate on vegetation must be assessed associated to hydrometeorological conditions due to the synergistic effect of these variables in wetlands ecosystems.plant community, livestock, wetlands, stocking rate.
Impact of color and anti-hail net installation system on microclimate and leaf water status in Vitis vinifera L. cv. Malbec in Mendoza, ArgentinaNahuel, C.G. (1)Castro, P. (1); Giménez, V. (1); Osorio, R. (1); Lázaro, H. (1); Gómez, A. (1); Nahuel, E.D. (1); Vico, M. (1); Luna, A. (1); Carbajal Ramos, I. (3); Prieto, J. (2)(1) EEA Rama Caída, National Institute of Agricultural Technology, Mendoza, Argentina (2) EEA Mendoza, National Institute of Agricultural Technology, Mendoza, Argentina (3) Faculty of Sciences Applied to Industry, National University of Cuyo, Mendoza, Argentinaver resumen adjuntoGrembiule, temperature, radiation, microclimate, water status, leaf water potential.
Chloroplasts localization of Citrus psorosis virus movement protein: implications on viral spread and host defense response evasionAna MarchesiniMarchesini A. (1); Robles Luna, G. (1); Mazzolenis, R. (1); Peña, E.J. (1)(1) Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas - UNLP, CONICET - CCT La Plata, Argentina.Citrus Psorosis is a slow progression disease that induces the formation of small chlorotic spots on young leaves of infected plants, and causes a progressive deterioration and potential death during following years. Its causal agent, Citrus psorosis virus (CPsV), is a tripartite, negative-sense RNA virus. RNA2 encodes a 54 kDa protein capable of self-cleavage, generating the movement protein (MP, 34 kDa) and protease (Pro, 20 kDa). MP localizes in chloroplasts (Chl) and plasmodesmata (PD), where it increases its size exclusion limit (SEL), and forms tubules that facilitate cell-to-cell virus movement.

We observed that chloroplasts, organelles involved in the synthesis of signaling hormones and plant defense, exhibit altered structure and organization in CPsV infected tissue. In silico analysis identified a chloroplast transit peptide (cTP) in MP sequence, and we have detected a significant number of chloroplast proteins in the MP interactome. Therefore, our objective is to understand the role of MP targeting to chloroplasts in the viral infectious cycle.

Using fluorescently tagged fusion proteins, we demonstrated that this cTP is sufficient to direct GFP to chloroplasts. Furthermore, the deletion of cTP abolishes MP targeting to the organelle, delays its accumulation at PD, and impairs both its ability to sustain viral movement and to increase the size exclusion limit (SEL). The use of heterologous cTPs fails to restore these functions.

The accumulation of callose at PDs is involved in the containment of pathogens at the infection site. The MP has the capacity to inhibit this defense mechanism induced by H2O2. This inhibitory activity is affected in cTP mutants.

These results indicate that the MP chloroplast targeting through its homologous cTP is associated with its ability to support virus movement, although the cTP deletion mutants are able to reach PD and suppress the defense responses analyzed so far.
chloroplast, movement protein, plasmodesmata.
Genetic progress in malting barley in Argentina under contrasting environmentsAbeledo LGIbañez, C. (1), Comacchio, J. (1); Rondanini, D.P. (1, 2); Miralles, D.J. (1, 2); Abeledo, L.G. (1, 2)(1) Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina. (2) CONICET – IFEVA, Buenos Aires, Argentina.Barley has been a crop traditionally destined for low productive environments in Argentina as well as worldwide. The objective of the work was to analyze the recent genetic progress for yield in malting barley cultivars in Argentina. A field experiment was carried out at the Faculty of Agronomy UBA combining 10 cultivars of malting barley released to the Argentinean market during the last 40 years and 3 sowing dates (early, S1; intermediate, S2; late, S3). Within each sowing date, the experimental design was completely randomized with three replicates. The experiment was conducted with irrigation, high soil nutrient availability, and control of pests, weeds, and diseases. At maturity, grain yield and its numerical component were measured. Mean yield in S1, S2, and S3 was 8209, 6261, and 3271 kg/ha, respectively. The genetic progress for grain yield was 131 kg/ha.year (R2= 0.68**) in S1, 40 kg/ha.year in S2 (R2= 0.27*), and without a significant trend in S3. The genetic progress in relative terms with respect to the mean yield of each sowing date was 1.5 and 0.6 %/year in S1 and S2, respectively, and null in S3. Grain number per m2 showed a significant trend with the year of release of the cultivars only in S1 (R2= 0.48**), while grain weight showed a positive trend in the three sowing dates (S1, R2=0.64**; S2, R2=0.34*; S3, R2=0.50**). In conclusion, the higher the productivity of the environment, the greater the genetic progress tended to be, both in absolute (kg/ha.year) and relative (%/year) terms. The positive trend of grain weight with the year of release of the cultivars revealed the relevance of grain quality as target of the breeding programs due to grain weight condition variables that define commercial quality such as grain nitrogen concentration and screening.grain yield, grain weight, grain number, Hordeum vulgare L., sowing date
Connection between AtSINA-L7 and auxin metabolismCarol Gabriela Tello LeónBusi, M.V.(1); Gómez-Casati, D.F. (1)Centro de Estudios Fotosintéticos y Bioquímicos, UNR-CONICET, ArgentinaThe gene Seven in absentia like 7 (At5g37890, SINA-L7) encodes a RING finger protein displaying E3 ubiquitin ligase activity. This protein is implicated in radiation response and is expressed across various developmental stages in nearly all plant tissues. Auxins hold a pivotal role in initiating and shaping the growth of leaves, flowers, and roots, primarily through cell division, with a notable emphasis on indole-3-acetic acid (IAA). Additionally, auxins possess the capability to coordinate a wide array of developmental responses within distinct tissue types.
Within plants, SINA-T5, a paralog of SINA-L7, actively facilitates ubiquitination-mediated degradation of NAC1, thereby exerting a negative regulatory influence on auxin signals. Notably, there are reports indicating that SINA-T5 (the homolog of SINAL7 in Arabidopsis thaliana) is intricately involved in the regulation of flowering processes. This involvement stems from its promotion of ubiquitin-mediated degradation of NAC1, ultimately leading to the attenuation of auxin signals.
The aim of this study is to comprehensively characterize AtSINA-L7 by utilizing two homozygous mutant lines of SINA-L7 sourced from A. thaliana plants (SALK_096989 and CS833574), and to explore its relationship with auxin metabolism. For the experimental phase, the application of the phytohormone AIA via spraying [10-8 M] over a period of 6 consecutive days was proposed. The preliminary results acquired demonstrated an approximate 15% reduction in aberrant siliques and a noteworthy 30% increase in seed count, among other observed outcomes. These findings underscore the substantial role of AtSINA-L7 in modulating developmental responses and governing auxin metabolism within plants.
Arabidopsis thaliana, auxins, metabolism, developmental responses
Exogenous ascorbic acid enhances the aluminum resistance of sensitive plants of Vaccinium corymbosumPaz Cárcamo-Fincheira (1)Adriano Nunes-Nesi (3), Braulio Soto-Cerda (4,5), Claudio Inostroza-Blancheteau(4,5), Marjorie Reyes-Díaz(1,2).1 Lab. de Ecofisiología Molecular y Funcional de Plantas, Depto. de Cs Químicas y Recursos Naturales, Facultad de Ingeniería y Ciencias, UFRO, Chile. 2 Center of Plant, Soil Interaction and Natural Resources Biotechnology, Scientific and Technological Bioresource Nucleus, BIOREN-UFRO, Chile. 3 Depto. de Biología Vegetal, UFV, Brazil. 4 Lab. de Fisiología y Biotecnología Vegetal, Depto. de Cs Agopecuarias y Acuícolas. UCT, Chile. 5 Núcleo de Investigación en Producción Alimentaria, UCT, ChileAscorbic acid (ASC), a small water-soluble molecule, is naturally synthesized in plants. The increased ASC pool provides a protective role for plants against abiotic stresses. In blueberry was suggest that ASC is a key molecule in the oxalate generation under Al-toxicity. Reactive oxygen species (ROS) are commonly increased by abiotic and Al-toxicity stresses, decreasing plant growth and development. Exogenous ASC application could be an effective approach to alleviating abiotic stresses.  This study aimed to evaluate the foliar ASC application at different doses (0, 50, 100, 200, and 400 mg L-1 ASC) and its interaction with Al-toxicity (400 µM Al), with six combinations in Star (Al-sensitive) under Hoagland solution, at 4.5 pH, for 28 days. It was determined net photosynthesis (Pn), relative growth rate (RGR), ASC concentration (reduced and oxidative forms, and its ratio), antioxidant activity (AA), and total phenols (TP). The results showed significant differences in all determinations, showing a significant interaction between doses and time of exposure. The Pn showed differences under 400 mg L-1 ASC x 400 µM Al (T6) at all times evaluated, increasing by 2.6, 1.7, and 1.3-fold. Likewise, the ASC concentration increased in the T6 by 1.5-fold at 28 days compared to T2 (0 mg L-1 ASC x 400 µM Al); while DHA concentration increased by 1.4-fold in T6 at 14, 21, and 28 days. Contrarily, ASC/DHA ratio and TP decreased in T6 at 28 days at 16 and 40%, respectively, compared to T2. On the other hand, RGR increased mainly at 28 days in the Star under 200 mg L-1 ASC x 400 µM Al treatment (T5) in 1.9-fold with respect to 0 days. In conclusion, ASC-applied increases Al resistance in Star cultivar of V. corymbosum, appear to be due to the antioxidant role as antioxidant, cofactor, and precursor of other molecules related to the Al-resistance mechanisms in plants. Acknowledgments: FONDECYT Postdoctoral N°3220674; FONDECYT Regular N°1211856 and N°1201749, and ANID/FONDAP/15130015.Al-resistance mechanism, blueberry, antioxidant activity, ascorbate.
Production of Nanobodies for Potato Virus Y (PVY) detectionGudesblat, Gustavo (1,5)Mora-Alvarado, Emilia (1); Bok, Marina (2,3); Parreño, Viviana (2,3); Ibañez; Lorena Itatí (4)ver documento adjuntover resumen adjuntoPotato virus Y, PVY, nanobody, VHH, recombianant protein expression, antibody, ELISA, pathogen detection, phytopathology.
Physiological responses of two species of the genus Colobanthus to water stress.Karla Villena Fernández (1)Gajardo, H. (1); Bravo, L.A. (1)(1) Laboratorio de Fisiología y Biología Molecular Vegetal, Departamento de Ciencias Agronómicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile.Colobanthus quitensis and Colobanthus apetalus (Caryophyllace) are two species adapted to cold environments. For C. quitensis ecotypes have been described in Antarctica (C. quitensis Antarctic ecotype) and also populations in the Andes of central Chile. There are also other less studied populations that inhabit the Andes of central-southern Chile (i.e., C. quitensis pobl. Conguillío). Colobanthus apetalus is a species that has been described from Patagonian sub-Antarctic areas. Adverse environmental conditions (e.g. freezing, intense winds, desiccants) are conditions that cause cellular dehydration. Therefore, these adaptive characteristics could also be extrapolated to other types of adverse conditions such as water stress. On this basis, we propose that the species C. quitesis Ec Antarctica will be more tolerant to water stress. The objective of this research is to compare the physiological responses of two species of Colobanthus spp. subjected to water stress. Two treatments were developed in the experiment, applied by means of irrigation restriction: moderate stress (MS) and severe stress (SS). Relative water content (RWC), photosynthetic capacity, transpiration and stomatal conductance were measured in each treatment. Severe water stress was the only one that caused a significant alteration in the plants, decreasing the gas exchange of C. quitensis Ec Antarctic by 64%, C. quitensis pobl. Conguillío by 80% and C. apetalus by 100%. Transpiration decreased by 74%, 84% and 90%, respectively, which is consistent with better stomatal control of C. quitensis Ec Antarctica. The hypothesis of this research is confirmed because the species C. quitensis Ec Antarctica showed greater tolerance to water stress, this is probably related to its high tolerance to freezing, since many traits are shared between plants tolerant to both stresses.Colobanthus, water stress, photosynthesis, stomatal conductance
Sunflower: Early sowing dates and their impacts on the frost resilience in Córdoba ArgentinaFabio, Ernesta Andrea (1)Grieu, Philippe (4); Bigatton, Ezequiel Darío (2); Salvay, María Laura (1); Biasutti, Carlos (3)1. Plant Physiology. Faculty of Agricultural Sciences (FCA). National University of Córdoba (UNC). 2. Agricultural Microbiology. Faculty of Agricultural Sciences (FCA). National University of Córdoba (UNC). 3. Plant Breeding. Faculty of Agricultural Sciences (FCA). National University of Cordoba (UNC). 4. INPT- École Nationale Supérieure Agronomique. UMR 1248 AGIR. National Polytechnic Institute of Toulouse. University of Toulouse, Castanet-Tolosan. France.Sunflower (Helianthus annuus L.) is an alternative crop in some soils where soybeans (Glycine max (L.) Merr.) are not suitable. The total sown area in Argentina was 2.15 million ha. for 2022-2023. Early sowing dates (SD) expose the crop to optimal thermal-photoperiodic conditions for achieving high yields, increasing the duration of the vegetative cycle, leaf number, and leaf area. However, early SD exposes the crop to frost stress in the early stages. Genotypic selection for cold stress tolerance is the main strategy for developing superior seed materials. This work aimed to evaluate the impact and adaptation to the frost of different sunflower genotypes. A trial was carried out at the FCA_UNC Campo Escuela (31° 28'S, 64°00'W) in 2021 using different commercial genotypes: Syngenta 3945 (SY3945), DOW MG 360 (DW); Nidera Confitero (NC), Syngenta 3980 (SY3980) and DK 4045 (DK). Plots of 14.5 m2 were used; each plot had four 7 m rows at 0.52 m spacing with a stand density of 5 plants m-2.  The sowing dates were: Aug-21, Sept-9, Sept-26, and Oct-23. The yield (Kg ha-1) and their numerical components were measured at R8. The results showed genotypic variability. 13 frosts (temperatures below 0°C) occurred between August and October. On average (across the genotypes), 15% of plants exposed to frost had multiple chapters, ramifications, and axillary chapters. This trait has been associated with genotypes susceptible to frost stress. The main contribution of this research was that in the early sowing dates, the plants increased the emergence–flowering stage. The yield was 6547 kg ha-1 on average in Aug-21, and the yield ranking from + susceptible to + tolerant was: NC < DK < SY3970 < DW < SY3945. This trait was associated with the number of grains per plant, in the case of frost-tolerant cultivars was 96% (2900 seeds plant-1) higher than susceptible ones (1400 seeds plant-1). These findings indicated the resilience of sunflower cultivars to frost in early sowing dates.sunflower, frost, genotypes, early sowing dates.
Water dynamics in plant cells: unraveling the interplay between redox state and metabolism statusCabadas manuelLascano, Ramiro Hernan, Robert, German.Unidad de Estudios Agropecuarios-UE, INTA, ArgetinaWater is the primary and essential component of all living cells. In plant cells, it constitutes approximately 90% of their total weight. However, the understanding of water's functions in living systems has evolved, revealing significant disparities when compared to in vitro solutions.

Our researchs focusses into the dipolar relaxation of water, within diverse tissues and cells of Arabidopsis thaliana, employing the well-characterized fluorophores ACDAN and PRODAN from the DAN probes series, commonly used in biomimetic systems. The tissues investigated encompass root cells (elongation zone, meristematic zone, and root cap) and leaf cells (epidermal, stomata, mesophyll cells).

The interpretation of our findings is anchored in the Association-Induction Hypothesis (AIH), an alternative perspective on cellular physiology that highlights the vital role of intracellular water's structure in sustaining the living state within cells.

Through our previous investigations, we have unveiled variations in the degree of intracellular water dipolar relaxation among different tissues and subcellular structures, underscoring the heterogeneity of this phenomenon within plant cells. Additionally, our observations indicate a dose-dependent impact of hydrogen peroxide treatments on intracellular water dipolar relaxation. While concentrations of H2O2 up to 8 mM result in a decrease in water relaxation, higher concentrations lead to an increase. Furthermore, concentrations above 16 mM trigger a notable escalation in cell death.

These dynamic changes are closely linked to the intricate interplay of redox regulation and metabolic states within plant cells, where adenosine triphosphate (ATP) serves as a crucial energy currency orchestrating cellular processes. The fluctuations in intracellular water dipolar relaxation appear to be tied to the ATP levels, revealing the pivotal role of this molecule in modulating cellular responses to oxidative stress and metabolic demands.
Water, dipolar relaxation, AIH, Redox state, ATP
Understanding the dynamics of assimilate demand and growth during grain filling in potential yield of summer maizeOgando FedericoVega,CGrupo de ecofisiologia de cultivos EEA INTA ManfrediHigh yield gaps have been reported for summer maize (SM) in Argentina, indicating unexploited potential. The potential yield (PY) of SM is influenced by factors like environmental conditions, genotype (G), and stand density (D). PY is closely correlated with kernel number (KN), but in some cases, setting higher KN could limit growth during the effective grain filling period (EGF). Assimilates demand during EGF (EDGF) can be quantified as the product between KN and the rate of grain growth. When EDGF exceeds the crop growth rate during the EGF (CGRegf), it may restrict PY. Understanding this dynamic is crucial for maximizing SM yield. This study aims to evaluate PY and the dynamics of EDGF versus CGRegf under different D and G combinations. One experiment was run during two seasons (2019-2020) with two factors: G (2) and D (4, 6, and 12 pl m2) in a split-plot design with three replications. Grain yield varied across D and ranged from 800 to 1817 kg ha-1 (p<0.05). The interaction D * G was significant, with G1 showing consistent yield increases with D, while G2 plateaued beyond 6 pl m2. KN explained 63% of yield variation and showed a positive correlation with EDGF (R2=0.8). EDGF varied from 18.6 to 31.4 g m2 day and was influenced by the interaction between year with both, D and G (p>0.05). Consistently EDGF was larger than CGRegf suggesting a source limitation during EGF, even under potential conditions. This source limitation was also evident in dry matter fluctuations (R3 vs R6) during EGF, with most treatments showing negative values (range +45 to -591 g m2), indicating biomass remobilization. In conclusion, our study highlights the complex interplay between G, D, and environmental factors at influencing yield in SM and highlights the role of KN in determining both grain yield and EDGF. The apparent source limitation in SM crops growing under no limiting resources highlights the importance of growth during EGF for defining YP. These results also rise concern of the potential impact of stressful conditions that can limit growth during grain filling, especially under environments that allow to set a high KN but limit source during EGF, like nitrogen or water shortages.
Characterization of AtSINA-L7 function in auxin metabolismTello León, CarolTello León, C.; Busi, M.V.; Gomez Casati, D.F.Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de RosarioThe gene Seven in absentia like 7 (At5g37890, SINA-L7) encodes a RING finger protein displaying E3 ubiquitin ligase activity. This protein is implicated in radiation response and is expressed across various developmental stages in nearly all plant tissues. Auxins hold a pivotal role in initiating and shaping the growth of leaves, flowers, and roots, primarily through cell division, with a notable emphasis on indole-3-acetic acid (IAA). Additionally, auxins possess the ability to coordinate a wide array of developmental responses within distinct tissue types.

Within plants, SINA-T5, a paralog of SINA-L7, actively facilitates ubiquitination-mediated degradation of NAC1, thereby exerting a negative regulatory influence on auxin signals. Notably, there are reports indicating that SINA-T5 (the homolog of SINAL7 in Arabidopsis thaliana) is intricately involved in the regulation of flowering processes. This involvement stems from its promotion of ubiquitin-mediated degradation of NAC1, ultimately leading to the attenuation of auxin signals.

The aim of this study is to comprehensively characterize AtSINA-L7 by utilizing two homozygous A. thaliana mutant lines of SINA-L7 (SALK_096989 and CS833574), and to explore its relationship with auxin metabolism. For the experimental phase, the application of the phytohormone AIA via spraying over a period of 6 consecutive days was perfoemed. Preliminary results demonstrated an about 15% reduction in aberrant siliques and a noteworthy 30% increase in seed number, among other observed outcomes. These findings highlight the significant role of AtSINA-L7 in regulating developmental responses and auxin metabolism in plants.
Arabidopsis thaliana, auxins, metabolism, developmental responses
Generation of bioinformatics tools for the integrative analysis of environmental, genomic and transcriptomic dataManuel Da PonteGendelman, M.; Rabinovich, A.; Chernomoretz, A.; Hernando, C. E.;Cálice Biotech, Argentina.As the generation of information accelerates, there is a growing gap between the speed of data production and the evolving capacity of the tools to analyze it. Many of the approaches currently used do not tend to focus on integrating the different layers of information that surround a particular biological system, but rather, border on superficiality by isolating and studying these layers separately. In this work, we sought to develop innovative bioinformatics tools that couple genetic and transcriptomic variability with environmental information. These tools were implemented using Python and R as programming languages, and they were tuned with data from different ecotypes of Arabidopsis thaliana from the 1001 genomes collection, which come from different geographic regions and are exposed to various environmental contexts. In the refinement process, promising results were obtained that served as validation of these tools. It was found that, as expected, there was a correlation between known flowering factors and the latitude where each ecotype grows. In addition, unsupervised clustering of the transcriptomic profiles was performed by means of graph-based algorithms. This mentioned analysis contributed to the validation of the tools since it showed that a large part of the genes whose expression was specific to particular groups were related to circadian rhythms and photosynthesis, identifying these genes as variability factors between ecotypes. Finally, we have extrapolated this analytical approach by applying the developed tools to sets of genes of agronomic interest, such as genes involved in crop metabolism and yield. Although many aspects remain to be improved, the results presented here confirm the potential of the tools generated thanks to the application of a novel holistic approach.bioinformatics, data science, transcriptomics
A new biolistic method in plants for barley transformation and regenerationMaría V. BusiGomez Ibarra, A.R. (1) Souza Canada, E.D. (1); Busi, M.V. (3); Permingeat, H. (1,2)1 Universidad Nacional de Rosario - Facultad de Ciencias Agrarias, UNR, Zavalla, Santa Fe, Argentina, CP 2125; 2 IICAR-CONICET, Zavalla, Santa fe, CP 2125; 3 Facultad de Ciencias Bioquímicas y Farmacéuticas, UNR-CEFOBI, Rosario, Santa Fe, Argentina CP:2000.There are methods of biolistic transformation of wheat from immature embryos that require the
plant to reach its stage of the spike cycle and subsequently its in vitro culture to regenerate. This
method is not applicable to many cultivars that are recalcitrant to in vitro culture. For this reason,
we developed a simple and reproducible method that was previously tested in wheat and now
developed in barley in this work. Through the use of biolistic DNA supply without culture or callus
regeneration, it consists of using the SAM (Shoot Apical Meristem) as an objective, by excision of
the first leaves of the embryonic axis, in which the meristem is cleared in order to be able to
regenerate a complete plant through it. From seeds soaked in water for 24 hours and disinfected,
they were exposed under a microscope and subjected to bombardment with tungsten particles
coated with the GFP gene construct, introducing DNA into the cell layer. Bombarded embryos were
grown to mature, stably transformed T0 plants and the integration of the GFP gene into the genome
was prolonged into the fifth leaf. The use of 1.1 μm particles (50 μg/μ) and a pressure of 900 psi-
6cm, analyzing their development days after sowing (DDS). For this, 6 repetitions of 15 embryos
each were used from two varieties of barley: Golden promise known for its use in vitro culture and
the Andreia variety known for its use in agricultural production and the brewing industry. This assay,
which resulted in increased maximal regeneration rates and transient GFP expression in SAM,
verifies that the method could potentially be used to generate stable transgenic lines for a wide
range of commercial barley cultivars.
Genetic transformation, reporter gene, molecular biology
Role of a submergence responsive Myeloblastosis transcription factor in the formation of lateral root organs in legumesReynoso, M.A. (1,2)Bori, C. (1), Ibarra, E. (1)(1) Instituto de Biotecnologia y Biologia Molecular, FCE UNLP CONICET, (2) Center for Plant Cell Biology, Universidad de California, RiversideLegumes can establish lateral roots (LR) and specialized symbiotic organs known as nodules, where rhizobia bacteria are allocated and fix nitrogen in an hypoxic environment. In Arabidopsis roots, local hypoxic niches control the establishment of LR, stabilizing transcription factors (TF) that repress auxin induced genes essential for LR development. Both roots at early stages of the symbiotic interaction with rhizobia and mature nodules show a significant accumulation of transcripts belonging to the submergence response families (SURF), some of which are evolutionarily conserved across angiosperms. Given the role of the hypoxic niches in the formation of lateral organs and evidence that indicates root nodule organogenesis co-opted the program of LR development, we decided to study one SURF coding for TF of the Myeloblastosis (MYB) family. In the model legume, Medicago truncatula, transcripts coding for this TF accumulate both at 60 hours post induction of LRs, in roots after 16 hours post inoculation with rhizobia and remain high in developing and mature nodules. To study whether this TF is involved in the development of LRs and during root nodule symbiosis, we generated two RNA interference (RNAi) constructs to induce post-transcriptional gene silencing for this MYB gene. We are currently studying the impact of its silencing in hairy roots of composite plants generated using Agrobacterium rhizogenes- mediated transformation. We evaluate the density of LRs, formation and morphology of nodules, and overall root and shoot mass. Early results indicate that silencing affect the number of nodules formed in roots with lower levels of MYB transcripts. We are conducting new experiments to validate these observations and will expand the analysis in retrotransposon-insertion mutants for this conserved TF in legumes.Symbiosis, conserved transcription factor, hypoxia, lateral roots
Evolutionary conserved submergence responsive transcription factors involved in the formation of lateral root organs in legumesIbarra EzequielZanetti María Eugenia, Reynoso MauricioInstituto de Biotecnología y Biología Molecular (IBBM) - CONICET - UNLPOxygen distribution controls the formation of lateral roots (LR) via molecular responses to hypoxic niches that originate during development. Local hypoxia stabilizes transcription factors (TF) that repress auxin induced genes essential for LR development. In addition to LRs, legumes form specialized lateral symbiotic organs known as nodules, where rhizobia are allocated and fix nitrogen in an hypoxic environment. At early stages of the interaction, roots show a significant accumulation of transcripts belonging to the submergence response families, which are evolutionarily conserved in angiosperms. Given this evidence and the role of the hypoxic response in the formation of lateral organs, we decided to study a family of genes coding for trihelix TFs, which are located in syntenic genomic regions. This family contains the gene Hypoxia Response Attenuator in Arabidopsis, which controls the anaerobic response to hypoxia. To characterize whether these TFs are involved in the mechanisms that take place during root nodule symbiosis and lateral root formation, we used the model legume Medicago truncatula. Transcripts for members of this family accumulate in roots after 24 hours post inoculation with rhizobia and remain high in developing and mature nodules. Using Agrobacterium rhizogenes- mediated transformation, we generated transgenic hairy roots that express RNA interference (RNAi) constructs that induce post-transcriptional gene silencing of members of this family. We are currently characterizing the impact of silencing of individual trihelix TFs in the development and density of LRs, the progression of rhizobial infection events, formation and morphology of nodules, and overall root and shoot mass. Early results indicate that silencing of these TFs affect the development of lateral organs in roots. Additional experimental evidence will help to elucidate the role of this conserved TF family in legumes.Symbiosis, conserved transcription factor, hypoxia, lateral roots
STUDY OF ZmNADP-ME3 TRANSCRIPTIONAL REGULATIONMariana SaigoRolle, Luciana M. , Gismondi, MauroCentro de Estudios Fotosintéticos y Bioquímicos (CONICET-UNR), Rosario, Argentina.The NADP-dependent malic enzyme (NADP-ME) catalyses the reversible conversion of malate to pyruvate and carbon dioxide, using NADP+ as a cofactor and a divalent cation essential for its activity. NADP-ME is widely distributed in nature, and each organism usually has more than one active isoform. In plants, with the exception of the NADPMEs directly involved in photosynthesis, the particular biological role of the remaining isoforms is unclear. In particular, ZmNADP-ME3 of Zea mays is expressed almost exclusively during grain development, is inducible with advancing dormancy and by the hormone ABA. Bioinformatic analyses of the genes encoding these enzymes and of embryonic NADP-MEs from other monocot species identified conserved arrangements of known and unknown cis-elements in the annotated transcriptional start site. To demonstrate the functionality of different fragments of the transcriptional start site of the ZmNADP-ME3 gene, they were cloned into a plasmid fused to the GFP reporter gene and used to transform 25-day post-pollination embryos by bioballistics. The strength of these fragments in directing RNA synthesis was assessed by fluorescence intensity and GFP expression by real-time RT-PCR. This resulted in the identification of regions required to regulate transcriptional initiation from this promoter. Conclusions: The regulation of ZmNADP-ME3 expression is complex and involves different elements and levels. In immature embryos the most important regions for ZmNADP-ME3 expression are contained in the first exon and first intron.maize, kernel, gene expression, ABA
Effects of wind and deficit irrigation on secondary metabolite production in red grapevine varieties: insights from a field trial in windy conditionsRodrigo AlonsoFlavio Muñoz (1), Ariel Fontana (1), Patricia Piccoli (1), Rubén Bottini (2), Federico Berli (1)(1) Instituto de Biología Agrícola de Mendoza - Facultad de Ciencias Agrarias de la Universidad Nacional de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas - Chacras de Coria, Mendoza. (2) Instituto Argentino de Veterinaria, Ambiente y Salud - Universidad Juan Agustín Maza - Guaymallén, Mendoza.Wind is an environmental signal that can act as a stressful condition, triggering increases in secondary metabolites, however, its specific impact on grapevines remains underexplored. Deficit irrigation (DI) is a management tool, known to stimulate the production of secondary metabolites associated with wine quality. Nevertheless, the effectiveness of DI can vary depending on the climatic conditions. We aimed to evaluate the individual and interactive effects of wind and DI in two red grapevine varieties, Malbec (Mb) and Cabernet Sauvignon (CS), which possess distinct phenotypic plasticity. A field trial was conducted over two growing seasons (2021-22 and 2022-23) in a vineyard located in the windy locality of Casa de Piedra, La Pampa. The grapevines were divided into two groups: protected plants (close to a poplar windbreak), and exposed plants (farther from the windbreak). Within each sector, half of the plants were subjected to DI, and the remaining half were maintained under normal irrigation conditions. During both growing seasons, the exposed plants showed reduced vegetative growth and increased cluster weight, with these effects being more pronounced in Mb. Both wind and DI significantly affected berry ripening: the sugar content and the skin polyphenols were increased additively by wind/DI treatment. The polyphenol profiles in the berry skins were modified by the treatments and varied between varieties. Also, it was observed that the gas exchanges, chlorophyll, and malondialdehyde were affected by the treatments, suggesting that wind and DI caused stressful conditions. In conclusion, these findings suggest that wind and DI can trigger complex physiological and biochemical responses, influencing both vegetative development and the production of secondary compounds. Interestingly, these responses exhibited dissimilar patterns between cultivars, however, it is noteworthy that in both varieties, the treatments increased desired compounds in wine.plant physiology, wind, water restriction, grapevine, polyphenols
GIS3 controls flowering through the thermosensory pathwayVirginia IbarraBarber, M.R. ; Jaskolowski, A.; Freytes, S.N.; Cerdan, P.D.Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET) (1)Floral transition in Arabidopsis thaliana is controlled by a complex gene regulatory network in response to endogenous and environmental cues. In order to comprehend how these signals are integrated, a genetic screening was conducted in our laboratory to identify genes potentially involved in the temperature response and regulation of flowering time. Among the mutants discovered, gigantea suppressor 3 (gis3) was identified. It has been reported that the protein encoded by GIS3 is associated with a group of histone methyltransferases. The point mutation present in gis3 results in an amino acid substitution in a protein-protein interaction domain. gis3 has an early flowering phenotype under long-day, intermediate-day, and short-day photoperiods. Additionally, it exhibits reduced responsiveness to changes in ambient temperature, particularly under long-day conditions.

A particular challenge is to identify the flowering pathways in which GIS3 are involved. Thus, we evaluated the flowering time in multiple mutants. On the one hand, we realized that GIS3 is in the same pathway of the flowering repressors FLC, FLM, MAF4 and MAF5. Furthermore, our results of transcriptomic data suggest that these flowering repressors are regulated by GIS3. On the other hand, we did double mutant analyses of gis3 and sdg8 – methyltransferase of H3K36 - and these findings suggest that gis3 and sdg8 are in the same pathway.

In summary, our results suggest that GIS3 plays a key role in regulating flowering time in Arabidopsis thaliana in response to ambient temperature.
epigenetics, molecular biology, flowering
Synchrony of the olive flowering in Catamarca-ArgentinaVanesa Estefanía AybarOrtiz, P.V. (1); Montalván, L. D. (1); Delgado, E. (1); Demín, P. E. (1); Prenol, L. V. (1)(1) Estación Experimental Agropecuaria Catamarca, INTA, Argentina.The Catamarca Province with warm winter conditions unlike olive growing areas of the Mediterranean Basin, becomes relevant as an area of study for the context of climate warming. Among the studies of the responses of olive (Olea europaea L.) flowering to environmental temperature, the effect on the synchrony of flowering became important. The work aims to provide information about the relationship between environmental temperature and synchrony of flowering. Phenology information was collected in periods from 2004 to the present in 2 sites, Sumalao and Capayán in the Catamarca, for different varieties and selections of the INTA Catamarca. Data from INTA station (2012 to 2023) and the National Meteorological Service (1973 to 2023) were available. In the phenological records, the length of flowering period and occurrence of more than one bloom in the same production cycle, were analyzed. The duration of the flowering period, throughout 19 years, did not have significant changes in the set of varieties analyzed; no cycles with more than one bloom were observed. The occurrence of early flowering was recorded in June 2023, with respect to September, which is the typical month of occurrence of the stadium, in a varietal selection of the INTA Catamarca. This refers to a desynchronized flowering, with stages from floral formation to fruits completely formed in the same secondary branch. The behavior described above could be linked to the fact that the year 2023 presented higher maximum and minimum temperatures and maximum values of thermal time to produce flowering with respect to equal periods of the historical series of data. More studies are being conducted on this report of early flowering, to test hypotheses about threshold temperatures, physiological mechanisms and gene expression and nutritional management and irrigation of the crop, which affect the flowering of the olive tree.Olea europaea L., climate warming, thermal time, flowering length, early flowering, bloom
Involvement of carbon and nitrogen metabolism in the recovery of plant health of Lotus spp.- Fusarium spp. interactionsAmira Susana del Valle NievaNieva, A.S.(1); Erban A. (2); Alsina, M.L. (1); Bernardi-Lima, N. (1); Ruiz O.A. (3); Kopka, J. (2)(1) Facultad de Ciencias Agrarias. Universidad Nacional de Catamarca. Argentina. (2) Max Planck Institute of Molecular Plant Physiology. Alemania. (3) Instituto Tecnológico de Chascomús. Argentina.The legume Lotus tenuis constitutes an important forage source in constrained environments due to its capacity to tolerate abiotic stress conditions, such as flooding, salinity and alkalinity. In these conditions, it establishes correlations with Fusarium species, ranging a continuum of interactions from mutualism to pathogenesis. Previous research on interactions between L. tenuis, L. japonicus and F. solani has revealed alterations in the carbon metabolism, concerning sugar mobilization. Further research revealed new interactions between Fusarium spp. and Lotus spp. including novel features in the contrasting outcome of both lotus species. The interaction between the model legume L. japonicus and F. culmorum, F. avenaceum and F. poae displayed strong pathogenic behaviours. The same group of fungi showed mild pathogenic (F. avenaceum) and recovery effects after 30 days of inoculation (F. culmorum and F. poae). We aimed to determine the dynamic of the metabolic response of L. tenuis against Fusarium spp. infection among the time, by using GC-MS approaches. The results obtained indicated changes in the carbon and nitrogen metabolism evidenced by the modification of sugars, acids and aminoacids levels, according to the Fusarium species. The interactions analyzed may indicate the increase in the use of citric and malic acid for carbon catabolism. Additionally, PLS-DA analysis showed the contribution of aspartic acid, glutamic acid, alanine and glycine to the recovery effect of L. tenuis against F. poae and F. culmorum. Our results indicate the possibility of the use of complementary metabolites in the response to pathogenic fungi to achieve the recovery of L. tenuis against Fusarium infection. The interactions between L. tenuis and F. poae and F. culmorum may involve the mobilization of nitrogenated compounds in the success of the pathogenic response and the further recovery of the plant health status.metabolomics, plant health, Fusarium spp., maltose, aminoacids
Making up for lost time: “Development of a New Breeding Techniques program and its application to the cultivation of Cannabis”Esteban HernandoCalice Biotech R&D TeamCalice Biotech - UNSAMCrop domestication began more than 10,000 years ago when societies turned to agriculture, achieving domesticated varieties of major crops around 4,000 years ago. Breeding is defined as the selection of a desirable/advantageous characteristic present in a subgroup of individuals of a domesticated crop, so can we really say that domesticated crops were bred? The improvement of crops in many cases is tied to the socio-cultural context, depending mainly on its level of demand and the prevailing legislation. In 1961, the psychoactive nature of Δ9-tetrahydrocannabinol (Δ9-THC) caused the prohibition of Cannabis cultivation. This banning resulted in a lack of knowledge of the physiological and molecular bases behind relevant processes for productivity, leading to technological backwardness of about 60 years for this crop. This scenario prompts us to ask ourselves: how can we make up for lost time? Calice Biotech is conceived as an R+D+i platform to accelerate plant improvement programs to the maximum. In our initial steps, we are applying new technologies to Cannabis breading as a proof of concept. For this, we developed two fundamental approaches: 1) Computational tools to integrate large volumes of information, thus enabling the discovery of genes suitable as breeding targets, in a fast and accurate way. 2) Molecular tools and the necessary technology for editing these target genes in plants using, for example, CRISPR-Cas9 tools. The technological challenge ahead of us is significant, however, our toolkit has proven sufficiently reliable to overcome the difficulties encountered so far. Thus, opening a promising path, full of opportunities for transferring our technologies to other crops.New Breeding Techniques , NBTs, Data Science
Deciphering dependent and independent roles for the families of circadian clock coactivators: what can we learn from high-order null mutants?María José de Leonede Leone, M.J (1); Croas, C.L (1); Yanovsky, M.J (1)(1) Fundación Instituto Leloir - IIBBA/CONICETThroughout evolution plants have developed sophisticated systems to stay in sync and even predict daily and seasonal cycles. This is possible thanks to an endogenous time-keeping mechanism known as the circadian clock. At the center of this system there is a network of proteins interconnected by transcriptional feedback loops that regulate the expression of ~30% of the transcriptome in Arabidopsis, rice, maize, papaya, poplar, and soybean.  Most core clock components are negative regulators of the expression, but there are two families termed REVEILLE (RVE) and NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED GENE (LNK) that act as positive co-regulators. Our group along with others have identified and characterized these families, and found that both have relevant roles in plants’ life.  Null mutants for these genes have shown similar phenotypes in many clock-controlled traits, still, there are some relevant processes such as the regulation of flowering time in which lacking LNK or RVE components doesn’t seem to have the same effect. In this study, to further understand the role of these families in the regulation of circadian outputs, we performed a side-to-side comparison of higher-order null mutants for each clade (rve3/4/5/6/8 and lnk1/2/3/4). By analyzing new available high-throughput transcriptomic data, and combining it with physiological assays we studied the impact each of these mutations have on processes such as flowering time, hypocotyl elongation, and stress responses. As a result, we were able to evaluate to what extent these mutants share common features, and how overlapping is the role of LNK and RVE genes in the regulation of circadian outputs.   In the past, the selection of natural allelic variants of clock components, such as LNK2 in tomato, has allowed the expansion of crops to new territories.  Thus, we believe that a better understanding of these families could be useful in the development of novel strategies for further crop improvement.Chronobiology, Circadian clock, Plant physiology, Transcriptional regulation
Assessing the small RNAs profile between potato diploid hybrid and its resynthesized allopolyploid.Zavallo, Diego (1)Leone M.(2), Cara N.(3), Cuello, R.(1), Marfil, C.M.(4), Masuelli R.W.(3), Asurmendi S.(1)(1) Instituto de Agrobiotecnología y Biología Molecular, INTA, Argentina. (2) Universidad Nacional de Urlingham, Argentina. (3) Instituto de Biología Agrícola de Mendoza, Argentina. (4) Estacion Experimental Mendoza, INTA, ArgenintaAllopolyploidy, characterized by interspecific hybridization combined with whole genome duplication, is a dynamic process that plays a crucial role in plant evolution, resulting in the emergence of new phenotypes. Polyploids often present phenotypic novelties that improve their adaptability, allowing them to compete with their parental species and occasionally to colonize new habitats. Whole genome duplication represents a “shock” to the genome and can trigger genetic and epigenetic changes that will lead to new expression patterns. In this work, we explore the effect of polyploidization on a diploid interspecific hybrid arising from the cross between the cultivated potato S. tuberosum and the wild potato S. kurtzianum. We focused on the sRNA profile of the parental diploid hybrid and its resulting allopolyploid to decipher the role of sRNAs in the context of epigenetic mechanisms, particularly in RNA-directed DNA Methylation (RdDM). We conducted a sRNA-seq experiment and implemented bioinformatic analysis on 21-22-nt and 24-nt length separately considering their distinct biogenesis and mechanism of action. The composition and distribution of different characteristics throughout the potato genome, especially those with differentially accumulated (DA) sRNAs, were evaluated and discussed. Furthermore, a subset of genes with DA sRNAs associated was selected to perform mRNA expression to address if the sRNA profile could have an impact on the transcriptome and in consequence on the phenotype. Interestingly, we observed that 24-nt DA sRNAs exclusively mapped to exons were linked to differentially mRNAs expression levels between genotypes. However, this behavior did not apply when 24-nt DA sRNAs were mapped to intronic regions. These findings highlight the intricate interplay between polyploidization, sRNAs population and gene expression in an interspecific potato hybrid.Allopolyploid, potato, sRNAs, epigenetic
What domestication took away: phytochrome B-mediated responses to environmental change.Milena E. ManzurVujanic, T. (1); Pinciaroli, C. (2); Talarico, L (2); Fernández, P.C. (3); Manzur, M.E. (1, 2)(1) Dep. Biol. Apl. Al. Cát. Fisiología Vegetal. FA, UBA, Argentina; (2) Instituto de Investigaciones Biotecnológicas, CONICET, UNSAM. San Martín, Buenos Aires, Argentina; (3) Centro de Investigaciones en Hidratos de Carbono, Dep. Quím. Org., FCEyN, CONICET, UBA, Argentina.Environmental changes impact on plant growth, metabolism and yield. In response, plants can adjust their phenotype and gene expression. However, due to domestication, some responses have been unintentionally modified, such as reduced investment in defences. An example is tomato crop (Solanum lycopersicum L.), which has only 5% of the genetic and chemical diversity of its wild relatives. In this study, the combined effect of high temperature (T) and low Red:Far-Red light ratio (R:FR) on growth and headspace volatiles (VOCs) composition in tomato plants S. lycopersicum and its wild relative S. pimpinellifolium were analyzed. It is hypothesized that S. pimpinellifolium will have a higher growth rate at a low R:FR ratio than its domesticated relative. It is also expected to have a higher VOCs diversity and, thus improved responses against herbivore insects. Seedlings of S. pimpinellifolium (LYC 2875) and the commercial species S. lycopersicum (cv. Moneymaker) were used. The combination of T and light factors resulted in four treatments (White Light and Control Temperature: WL-CT, Far-Red and Control Temperature: FR-CT, White Light and High Temperature: WL-T+, Far-Red and High Temperature: FR-T+), which were applied four weeks after emergence for ten days. Height was periodically recorded, and VOCs were collected at the end. Preliminary results show that growth rate was similar among genotypes, although there was an effect of the combined treatments (FR-T+ vs. WL-CT: P=0.045). The effects on final height in S. pimpinellifolium would be explained mainly by the effect of Far-Red and not by temperature since growth was inhibited at 30 °C (WL-T+ vs. WL-CT: P=0.618). It is concluded that the phenotypic plasticity of wild species should be considered to improve the response of domesticated species to deal with environmental changes.Climate change, defences, Far-Red light, growth, phenotypic plasticity, Phytochrome B, Solanum, temperature, VOCs.
Convergence between shade and submergence responses.Rocío FernándezRomina SellaroInstituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, IFEVA, Argentina.In the coming years, an increase in flooding is expected in our country due to the impact of climate change, which could produce water stress in the affected vegetation. Some plants have growth responses to escape from these unfavorable conditions either through the active promotion of organ development, such as stems, petioles and leaves that elongate or changes in angle in response to submergence. These morphological changes resemble those experienced by plants in response to the presence of neighboring plants. Given that some species show this convergence in phenotype in the face of different environmental stresses, it is plausible to hypothesize that they share signaling pathways and that if they occur simultaneously they could have a synergistic effect. Preliminary data from our working group have shown that the transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4), which plays a central role in regulating shade avoidance responses, is also involved in responses to submergence. Many of the PIF4 targets that cause hypocotyl elongation are involved in auxin synthesis and signaling, among them is AUXIN/INDOLE-3-ACETIC ACID 19 (IAA19). The aim of this work was to evaluate the role of IAA19 in the responses of Arabidopsis thaliana to shade and submergence conditions. Hypocotyl length responses of wild-type and iaa19 mutant plants and IAA19 expression were analyzed using two transgenic lines with the IAA19 promoter fused to reporter genes (Gus and Luciferase) under shade and submergence conditions. We found a synergistic response in IAA19 expression when plants were exposed with both stresses together. These results suggest that auxins participate in the convergence between the signaling pathway triggered by flooding and shade.

shade, sumergence, molecular biology, environmental
Nitric oxide regulation of temperature-dependent growth in Arabidopsis seedlingsTebez, Nuria Malena (1)Iglesias, M.J. (2); Correa-Aragunde, N. (1); Casalongué, C.A. (1); Terrile, M.C. (1)(1) Instituto de Investigaciones Biológicas (IIB), CONICET-UNMDP, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata. Mar del Plata, Argentina. (2) Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-UBA, Buenos Aires, Argentina.Plasticity is the capacity of plants to adjust their growth to environmental changes. Slight temperature increases prompt Arabidopsis seedling growth via auxin synthesis. In addition, these conditions also induced the accumulation of the molecular chaperone HSP90, stabilizing the auxin co-receptor TIR1, crucial for auxin signaling. Nitric oxide (NO) is a key molecule implied in the regulation of different auxin-dependent physiological processes. This work aimed to determine if NO contributes to modulating auxin-mediated growth in a temperature-changing environment in Arabidopsis. Elevated temperatures (29 ˚C) elicited significant elongation responses in multiple plant structures, including the hypocotyl and root architecture. We observed that treatment with cPTIO, a well-established nitric oxide (NO) scavenger, suppressed different seedling growth responses. cPTIO also inhibited auxin-induced hypocotyl elongation and lateral root production. These phenotypes are in concordance with the suppression of auxin response marker genes (DR5-GUS and MSG2-GUS). Additionally, seedlings triggered an increase in NO levels when grown at 29 ºC. We hypothesize that NO might play a crucial role in regulating the stability of the auxin co-receptor TIR1, adding a new layer of regulation influencing plant growth responses under changing temperatures. Supported by Agencia I+D+i, CONICET, and UNMdP.Arabidopsis, auxin, nitric oxide, temperature-mediated growth, auxin co-receptor
Dissecting PLASMODESMATA-LOCATED PROTEIN 5 functional domains.Gabriel Robles LunaGabriel Robles Luna (1)* Jiefu Li (2), Xu Wang (1), Li Liao (2) and Jung-Youn Lee (1)(1) Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USA Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 115 49 y 50 (1900), Buenos Aires, La Plata, Argentina. (2) Department of Computer and Information Sciences, University of Delaware, Newark, DE 19716, USA. *Present address: Instituto de Biotecnología y Biología Molecular (IBBM, CCT-CONICET-La Plata)Cell signaling requires that the components of the signaling circuit be located at a specific niche or compartment, where protein-protein interactions and conformational changes allow an effective response for a given stimuli. A subset of well-known plant receptor-like proteins (RLP) localizes to plasmodesmata (PD), nanochannels that connect the cytoplasm of adjacent cells. These RLP regulate the conductivity of distinct molecules which in turn impact almost every aspect of plant physiology.

We focus our study in PLASMODESMATA-LOCATED PROTEIN 5 (PDLP5) a well-known RLP involved in regulating PD upon pathogen infection and during development. Callose levels at the neck region of PD reduce or increase the cytoplasmic sleeve that connects both cells affecting PD conductivity, therefore, the balance between synthesis and degradation of callose at PD is considered the main way of regulation. The molecular features allowing PDLP5 association with PD and the domains involved in PD conductivity regulation are still unknown.

Using targeted mutagenesis, machine learning algorithms and advanced fluorescence microscopy we found that the transmembrane domain (TMD) is important for signal transduction upon pathogen infection. TMD is involved in protein-protein interaction where an AXXXG evolutionary conserved domain is necessary for proper function. Swapping PDLP5 TMD by TMDs of different sizes and sequences does not affect PD localization, which indicates the PD targeting signal does not involve the TMD. We found the PD targeting signal is located at the extracellular juxtamembrane region of PDLP5 and used this information to train custom-built machine-learning algorithms to predict the signal of other PDLPs and type I transmembrane proteins such as STRUBBELIG (SUB) and CRINKLY4 (ACR4). These signals were validated in vivo.

Our results show that the extracellular juxtamembrane region is important to place PDLP5 at PD and the TMD essential to exert the antiviral action.
Plasmodesmata, machine learning, transmembrane domain, targeting signal
Unraveling the significance of arginine methylation in AGO1Andrea Martín-MerchánAntonela Lavatelli, German Rosano, Nicolas Bologna.Center for Research in Agricultural Genomics (CRAG), Barcelona, Spain.Argonaute proteins (AGOs) are crucial for small RNA-guided gene silencing in plants. Post-translational modifications (PTMs), including arginine methylation, impact AGO activity and specificity. Despite extensive study in animals, plant AGO arginine methylation remains poorly understood. Focusing on AGO1 in Arabidopsis thaliana, we identified eleven potential arginine methylation sites in the N-terminal region and three in the C-terminal segment. Immunoprecipitation and mass spectrometry confirmed symmetric dimethylarginine modifications in AGO1. Transgenic lines expressing wild-type AGO1 or arginine-mutated AGO1 pinpointed the essential arginines responsible for methylation. Methyltransferase showed a strong interaction with AGO1, and its role in AGO1 methylation was validated through mutant backgrounds. Our study also explored potential interactions with methylation readers and putative methylation sites in other AGOs. These findings shed light on the regulatory mechanisms of AGO1 methylation, offering insights into small RNA-guided gene silencing pathways in plants. Understanding arginine methylation in AGO1 may unveil the complexities of RNA silencing mechanisms in diverse plant species.Argonautes, AGO1, Methylation, RNA silencing, Arabidopsis thaliana, Post-translational modifications.
Iron content in anthocyanin-deficient mutants of Arabidopsis thalianaMiguel VizcainoGomez-Casati, D.F. (1); Pagani, M.A. (1)(1) Centro de Estudios Fotosintéticos y Bioquímicos, UNR-CONICET, ArgentinaIron (Fe) is a crucial micronutrient for plant development, representing a significant limitation to their growth and affecting the quality of their edible parts. Despite the abundance of Fe in soils, its low bioavailability, especially in alkaline environments, becomes the main restricting factor for plant productivity. The aim of this study was to characterize iron metabolism in Arabidopsis thaliana mutants deficient in anthocyanin biosynthesis. For the experimentation, wild-type (Col-0) and mutant (TT4, 3GT, 5GT and TT19) lines were selected. These mutants previously showed altered expression of six genes (bHLH38, bHLH39, IRT1, FEP2, BTSL1, BHLH100) related to iron deficiency responses under anthocyanin-inducing conditions. To quantify the concentration of Fe in the tissues, the ICP-MS technique was used after digesting the samples with 65% HNO3 at 92°C. Iron accumulation was observed by Perls staining performed on 7-day-old seedlings cultivated on MS Agar medium. To measure FRO2 activity, the roots were submerged in a solution containing  Fe (III) EDTA,  and the Fe(II) chelator BPS to detect iron reduction at 535nm. As results, ICP-MS revealed that all mutant lines had the same Fe concentration in roots and higher Fe content in leaves than Col-0, but only 5GT and TT19 had higher seed Fe content. Perls staining indicated that TT4 showed lower iron coloration compared to the other lines. The FRO2 assay showed lower activity in 5GT and TT19 mutant roots compared to all the other lines. Additionally, TT19 exhibited a much greater length and quantity of secondary roots compared to the other mutant lines and Col-0. Altogether, these results point to an alteration in the mutant lines Fe homeostatic mechanisms.A. thaliana, iron, anthocyanins, FRO2
Getting out of the shade: characterization of the transcriptional network that modulates shade avoidance responses in soybean.Luciana BianchimanoEsteban Hernando, Daniel Careno, Ezequiel Marchionni, Maximiliano Marzetti, Carlos Dezar, Martin Vasquez, Santiago Mora Garcia, Marcelo Yanovsky, Jorge Casal(1) Fundación Instituto Leloir, IIBBA, CONICET. (2) INDEAR Instituto de Agrobiotecnología Rosario. (3) IFEVA, Facultad de Agronomía, UBA-CONICET.The demand for food and vegetable oils and the use of crops for industrial purposes is increasing significantly. In modern agriculture, the increase in production is linked with the increase of planted area, which presents ecological drawbacks, and to the intensification of grain production per unit area. One of the ways to increase productivity per unit area is to increase sowing density. However, plants grown at high crop densities receive reduced light irradiance because of mutual shading. To avoid shade, some plants readjust phenotypic traits such as growth rates of the stems, internodes, and petioles. Collectively, these responses are known as the shade avoidance syndrome. Generating shade-tolerant plants is the target for breeders to achieve high-yielding crops in a dense plantation. To reveal the molecular mechanisms behind shade avoidance in soybean (Glycine max), plants were grown in contrasting densities in the field and under simulated shade in controlled conditions. We performed a high throughput transcriptome analysis of petioles and leaves that allowed us to develop a tissue-specific shade avoidance gene expression network. Our work is the first to describe the molecular orchestration behind soybean shade avoidance responses, as a starting point to introduce novel approaches for crop improvement.Shade avoidance, crop improvement, soybean, transcriptional regulation
Native strain Enterobacter 64S1 enhances drought tolerance and melatonin levels of tomato plantsAna CohenJofré, M.F.; Mammana, S.; Pérez-Rodriguez, M.M.; Gomez, F.J.V.; Silva, M.F.; Cohen, A.C.Instituto de Biología Agrícola de Mendoza - Facultad de Ciencias Agrarias (CONICET-Universidad Nacional de Cuyo), Chacras de Coria, Mendoza, Argentina.In arid and semiarid regions, drought negatively impacts agriculture with severe losses in crop yields. Plant Growth Promoting Rhizobacteria (PGPR) are a sustainable alternative to improve crop production decreasing the fertilizer use. Furthermore, the use of PGPR in plants grown under stress conditions such as drought, salinity, or high temperature, mitigates the effects of stress. Enterobacter 64S1 is a native PGPR isolated from tomato crops of Mendoza. Recently, it has been reported that this strain is able to produce the hormone melatonin (MT) and increases the content of endogenous MT in plants of Arabidopsis thaliana under drought stress. Melatonin protects plants against biotic and abiotic stress, e.g., acting as a scavenger of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Therefore, the aim was to determine the effect of inoculation with the Enterobacter 64S1 strain on tomato plants under drought stress conditions and irrigation at field capacity. The plants were grown in a greenhouse for 4 weeks. The treatments were: 1) control and 2) 64S1 strain. After ten days of the inoculation treatment, water stress was applied on half of the plants in each treatment (n=15), while the rest was irrigated to field capacity (well-watered plants, WW). The soil moisture in stressed plants was kept at 30% of field capacity for 15 days by adding lost water. Then, at the end of the treatments, morphological, physiological, and biochemical variables were determined. In addition, plant endogenous MT production was measured in tomato leaves. The inoculated plants under drought stress presented a greater leaf area, stem height and dry weight, total chlorophyll content, and Fv/Fm levels. In addition, Enterobacter 64S1 increases the endogenous MT content in tomato plants under drought. This native strain improved the tolerance of tomato plants to drought by improving plant growth, total chlorophyll levels and the maximum efficiency of photosystem II.melatonin, PGPR, tomato, Enterobacter, drought
Embryogenesis in plant: the mitochondrial pentatricopeptide repeat protein EMB2217 is essential to sustain embryo development in Arabidopsis thalianaMarchetti, FernandaBalestieri, N. (1); Valiñas, M. (1); Pettenazza, J. (1); Berdun, F. (1); Mizrahi, R. (2); Ostersetzer-Biran, O. (2); Pagnussat, G. (1); Zabaleta, E. (1)(1) Biología de Organelas y Desarrollo, Instituto de Investigaciones Biológicas (IIB) CONICET, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina. (2) Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, IsraelEmbryogenesis is a fundamental process for plant life being finely regulated by different signaling pathways. EMB2217, which encodes for a protein with pentatricopeptide repeats (PPR) is essential for embryo development. PPRs proteins are involved in RNA metabolism mainly within mitochondria and chloroplasts. The EMB2217 null mutants display an embryo-lethal phenotype, with the affected embryos showing significant developmental delay. EMB2217 proteins localize within mitochondria. Due to its role in RNA metabolism, we analyzed the relative expression of mitochondrial transcripts in mutant seeds. Several RNA transcripts were affected, suggesting an important role of EMB2217 in mitochondrial RNA metabolism. Due to embryo-lethality, it is not possible to obtain mutant adult plants. However, we have recently managed to partially rescue homozygous mutant growing seeds in sucrose supplemented medium. The seedlings showed a severe defective phenotype with almost null leaf development and no roots, likely due to impaired regulation of the redox state in embryos. Accordingly, using molecular probes for ROS detection during the early stages of development, a ROS imbalance in mutant compared to the WT embryos was observed. To further study EMB2217 mutants, we generated lines complemented with EMB2217 gene under the ABI3 promoter which is specifically expressed during embryogenesis. We obtained homozygous mutant plants suggesting that embryogenesis was overcame. However, rescued plant has an abnormal phenotype characterized by a little size after a month of growing on soil, several small leaves, and scarce tiny siliques. Currently, we are studying mitochondrial complexes protein profile in order to determine mitochondrial electron transport chain protein composition. Taken together, the findings indicate a crucial function for the PPR EMB2217 protein in mitochondrial metabolism, not only during Arabidopsis embryogenesis but also throughout adult life.

embryogenesis, mitochondria, EMB2217
Autophagy as an energy regulator? Its impact on the growth and development of P. patensFranco LiberatoreFranco Liberatore (1); Georgina Pettinari (1); Esteban Schenfeld (1); Ramiro Lascano (1,2); Laura Saavedra(1,2)(1) Unidad Ejecutora de Doble Dependencia INTA-CONICET (UDEA), Córdoba, Argentina. (2) Cátedra de Fisiología Vegetal, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Argentina.Autophagy is a crucial cellular process responsible for the degradation and recycling of cellular components. In plants it plays a key role in the modulation of growth and development, as well as in stress responses, providing both pro-life and pro-death functions. Even in optimal conditions, the metabolic state of the cell is known to affect and be affected by autophagy. The bryophyte Physcomitrium patens represents an ideal model to study this process in relation to apical growth and the transition of 2D to 3D growth. In this plant, autophagy is activated by darkness during the night, and it is known that loss of autophagic function mutants such as atg5 and atg7 show accelerated senescence and impaired growth, effects which are exacerbated under nutrient insufficient conditions.

We set out to gauge the metabolic state of these mutants during their normal day-night cycle by measuring their starch, sugar, and adenylate content in comparison to the wild-type. We found that the autophagic mutants show a lower amount of starch, but, surprisingly, a higher ATP:ADP ratio than the WT, while the sugar content differed according to each kind of sugar. We also studied the effects of different sugars on the growth and development of these lines, and found that glucose delayed the transition to 3D growth and reverted the senescent phenotype of atg5, effects which were not replicated by sucrose. Furthermore, glucose and sucrose had distinctive effects on autophagic activity during the night. Further research is ongoing to dissect the origin of the senescence shown by atg mutants, by analyzing their redox state and the cell death pattern observed along pronotema filaments.

Our results provide clues that autophagy is an important process for maintaining the metabolic and energetic status of plants during the diurnal cycle, and that different sources of energy can regulate this process in distinct ways, impacting on the modulation of plant growth and development.
autophagy, P. patens, apical growth, growth & development, energy, senescence, sugars
Unraveling differential roles of ATG14 and VPS38 in Physcomitrium patens apical growthLaura SaavedraPettinari, G. (1); Liberatore, F. (1); Lascano, R. (1,2)(1) Unidad Ejecutora de Doble Dependencia INTA-CONICET (UDEA), Córdoba, Argentina, (2) Cátedra de Fisiología Vegetal, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba; Córdoba, Argentina.PI3P is a key regulator of membrane dynamics and trafficking processes, synthesized by VPS34. This kinase associates with VPS15 and ATG6, and forms two complexes (C) that differ in one subunit: C-I, with ATG14, participates in autophagy, and C-II, with VPS38, is involved in endosomal trafficking. In plants, the function of ATG14 and VPS38 has not been assessed in the context of apical growth, nor in evolutionarily distant organisms such as bryophytes. Herein, we use Physcomitrium patens protonemata, an apical-growing tissue comprising two functional and morphologically different cell types (chloronema and caulonema), as a model to address these areas.

We first compared gene expression in chloronemata- and caulonemata-rich media, revealing distinct patterns for VPS38 and ATG14 in each cell type. Subsequently, we examined changes in PpVPS34pro: PpVPS34-citrine expression during caulonemata induction (exogenous auxin or nitrogen deficiency). Our results indicated increased fluorescence intensity in chloronemal cells, which then differentiated into caulonema.

To discriminate whether the induction of caulonema development is associated with PpVPS34 function in autophagy or endocytic trafficking, we generated moss atg14 and vps38 knock-out lines. The atg14 mutants exhibited an early-senescence phenotype, similar to atg5 mutants, while the vps38 lines showed a marked reduction in gametophore size and rhizoid development without early senescence symptoms. Moreover, the percentage of caulonemal filaments decreased in atg5 and atg14 lines, suggesting that autophagy participates in caulonemata development, although it is not essential.

Overall, atg14 and vps38 phenotypes suggest that C-I and C-II participate in different aspects of apical growth and development, promising to be useful tools to dissect the autophagic and endocytic trafficking roles of PI3P. In addition, results indicate the participation of autophagy in apical growth and caulonemata development.
Physcomitrium patens, development, phosphoinositides, Atg14, Vps38, autophagy
Yield generation and radiation use in hybrids with and without a genetic alteration in height.Pluda, P. (1-2)Villavicencio, J. (1-2); Rotili, D.H. (1-2); Uribelarrea, M. (3); Röig, J. (3); Maddonni, G. (1-2); Cagnola, J. (1-2)(1) Facultad de Agronomía, Universidad de Buenos Aires. (2) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (UBA-CONICET). (3) Bayer Crop Science Argentina.Brachytic maize hybrids (br2) reduce internode growth, and their shorter stature prevents costly yield losses due to lodging, especially in late plantings or windy regions. However, the impact of br2 on yield in a given site and season, which depends on cumulative intercepted radiation (related to interception efficiency, IE), its conversion into biomass (through radiation use efficiency, RUE), and its partitioning to ears (harvest index, HI), remains unknown. Plant height modifies these efficiencies. Our objective was to compare the br2 hybrids and their traditional iso-hybrids (same genetic base without short-stature mutation), analyzing IE, RUE, and HI. We cultivated two pairs of maize hybrids (1 and 2), each in the br2 (S) and traditional (T) versions, planted at 4, 8, and 16 pl m-2 in a split-plot design under irrigation, with high fertilization levels. An alfa = 0.05 was considered for comparisons between iso-hybrids. The hybrid x density interaction was non-significant for yield. Grain yield was higher for T1 than for S1, while there were no differences between T2 and S2. Also, the yield was lower at 4 pl m-2 and maximized at 8 and 16 pl m-2. All hybrids reached the critical leaf area index (IE > 0.95), and iso-hybrids had similar cumulative intercepted radiation. By contrast, density affected these variables, as the 4 pl m-2 only reached IE = 0.9, determining a lower cumulative intercepted radiation (IE: 4 < 8 < 16 pl m-2). RUE was higher for T1 than for S1 but similar between T2 and S2, while HI did not differ between iso-hybrids. For both hybrid pairs, RUE increased with density, while HI was similar across densities for pair 2 and lower at 16 pl m-2 than 4 or 8 pl m-2 for pair 1. In conclusion, br2 did not affect IE, RUE, HI, or yield for hybrid pair 2, but a lower RUE was determinant of a lower yield for S1 versus T1, suggesting that br2 could be a beneficial technology against lodging without negative effects on yield depending on the hybrid.Dwarf maize, auxine, lodging tolerance, architecture
Yield and grain number determination in maize iso-hybrids with and without genetic alteration of heightVillavicencio, J.1-2Pluda, P.1-2; Cagnola, J.1-2; Uribelarrea, M.3; Röig, J.3; Maddonni, G.3; Rotili, D.H1-2.(1) Facultad de Agronomía, Universidad de Buenos Aires. (2) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (UBA-CONICET). (3) Bayer Crop Science ArgentinaHarvested yield of maize decreases in environments with strong winds due to lodging. Brachytic hybrids (br2) reduce this risk due to their short stature. However, the eco-physiological bases determining the yield of br2 are unknown. Our objective was to analyze the impact of the modification in the BRACHYTIC2 gene of maize on yield, numerical components, and functional mechanisms determining grain number [plant growth rate during the critical period (PGRCP), the relationship between grain number per plant (GNP) and PGRCP, the ear partitioning index (ear growth rate during the critical period versus PGRCP) and reproductive efficiency (grains per ear versus the growth rate of the apical - E1 - and sub-apical - E2 - ear during the critical period)]. Two traditional hybrids (T1 and T2) and their br2 iso-hybrids (S1 and S2) were planted at three densities (4, 8, and 16 pl m-2) in a split-plot design. Comparisons were made between iso-hybrids (pairs 1 and 2) considering an alfa = 0.05. Grain yield was higher for T1 than for S1. T1 showed a higher GNP at 16 and 4 pl m-2 but there were no differences between hybrids in grain weight. In pair 2, yields and its components did not differ at any density. In all cases, the yield was lower at 4 pl m-2 and maximized at 8 and 16 pl m-2. T1 had higher PGRCP, growth rate of E1 and of vegetative organs than S1. In pair 2, at 4 pl m-2, PGRCP was lower in for S2 than T2 due to a lower growth rate of vegetative organs, with similar growth rates of E1 and E2, while at 8 and 16 pl m-2 there were no differences between hybrids. The partitioning index was higher for both br2 hybrids for E2, while for E1 it was higher for S2 than for T2, with no differences in pair 1. Reproductive efficiency was similar between iso-hybrids. In conclusion, compensation among functional attributes explained that yield did not differ between iso-hybrids for the pair 2 but the higher vegetative and E1 growth rates of T1 versus S1 caused a higher yield for T1.Dwarf maize, auxine, lodging tolerance.
Did selection for tolerance to high plant density improve maize growth response in water stress conditions?Cagnola, J. (1-2)Álvarez Prado, S. (2-3-4); Cabrera-Bosquet, L. (7); Lis, M. (7); Le Roy, R. (7); Combes, M. (7); Suard, B. (7); Rosello, A. (7); Fournier, R. (7); Welcker, C. (7); Amas, J. (5); Otegui, M. (1-5); Tardieu, F. (7); Casal, J (1-2-6).ver documento adjuntover resumen adjuntoBreeding, water use, architecture.
The impact of canopy senescence on percentage grain nitrogen concentration and grain yield in maizeGuiamet Juan JoséMontenegro Mariano1, Antonietta Mariana1, Girón Paula2, Antonelli Cristian1, Bartolozzi Mauro1, Martínez Santiago1, Guiamét Juan José11Instituto de Fisiología Vegetal (INFIVE)- UNLP CONICET, La Plata, Argentina,2 Estación Experimental Agropecuaria INTA, General Villegas, ArgentinaIn maize (Zea mays L.) genotypes with a delayed canopy senescence behavior often develop grains with lower % concentration of N (e.g., Antonietta et al., Field Crops Res. 155: 111-119, 2014). To assess if delayed canopy senescence is associated to lower % concentration of grain nitrogen in a larger set of hybrids, the senescence behavior of 28 hybrids was determined and key senescence parameters were correlated with mature grain %N content. Two field experiments were conducted in General Villegas (GV, 2016-2017) and La Plata (LP, 2018-2019), with seeds planted in rows (0.5 m apart in GV, 0.7 in LP), fertilized to prevent mineral deficiencies. The canopy was divided into three thirds, and senescence of each third was followed by estimating green leaf area visually at weekly intervals. Green leaf area was fitted to linear regressions during the initial slow and the late fast senescence phases, and a breaking point was calculated as in Borrás et al. (Field Crops Res. 82: 13-26, 2003). In both experiments, hybrids differed significantly in terms of the time of the breaking point, the slope of the late fast senescence phase, and grain %N. In GV, senescence rate of the lower third of the canopy was positively related to %grain N but there was no relationship in LP. Time to the breaking point between the slow and fast phases of senescence of all thirds of the canopy were positively correlated with %grain N in LP. A delay in the onset of the fast phase of senescence in the mid and upper thirds of the canopy in GV, and of all canopy layers in LP correlated with grain yield. This suggests that while delayed senescence may result in higher grain yields, excessive delay of senescence in the lower canopy strata may compromise N availability for grain growth under certain environmental conditions.

maize, canopy senescence, percentage grain nitrogen, grain yield
MAIZE GRAIN DRY-DOWN: IMPROVING PREDICTIVE MODELSYesica ChazarretaCarcedo, A.J.P. (1); Alvarez Prado, S. (2,3); Massigoge, I. (1); Amas, J.I. (4); Fernandez, J.A. (5); Ciampitti, I.A. (1); Otegui, M.E. (6,7).(1) Department of Agronomy, Kansas State University. (2) IICAR – CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario. (3) Cátedra de Sistemas de Cultivos Extensivos-GIMUCE. Facultad de Ciencias Agrarias, Universidad Nacional de Rosario. (4) Corteva Agriscience. (5)The University of Queensland. (6) CONICET en EEA INTA Pergamino. (7) Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires.Predicting the optimal harvest date after crop physiological maturity is highly relevant for maize (Zea mays L.). While harvesting before achieving commercial kernel moisture implies additional costs of grain drying, a delayed harvest of maize crops is linked to grain yield and quality losses. Grain dry-down after physiological maturity follows a curvilinear response over time until equilibrium moisture is achieved and is affected by a post–maturity kernel dry-down coefficient (k), which indicates the resistance to water diffusion and refers to the proportion of moisture that can be exchanged in each time step. Previous dry-down models for estimating changes in kernel moisture considered the post–maturity kernel dry-down coefficient as a constant value. Current changes in farming management practices, particularly the delay in the sowing date expose kernels to diverse environmental conditions during the dry-down, affecting the capability of available models to capture the kernel moisture loss. The main objective of this work was to identify weather variables affecting the post-maturity grain dry-down coefficient to develop models to predict kernel moisture loss and time to harvest under a wide range of sowing date environments. Kernel moisture datasets from field experiments in Pergamino (Argentina) and Kansas (US) were used for training and testing post-maturity grain dry-down models. Two k coefficients were defined based on the solar radiation and the vapor pressure deficit explored during the pre- and post-maturity periods (kpre and kpost). Models including kpre and kpost were tested under a wide range of sowing date environments, presenting high accuracy in predicting kernel moisture (R2 ~ 0.80; RRMSE ~ 0.15) and harvest readiness (R2 = 0.99; RRMSE ~ 0.05). This study provides the foundation for incorporating maize grain dry-down models in interactive digital platforms to estimate harvest time to assist farmers and agronomists with this critical decision.
A role for phytochromes in red light mediated alternative splicing in Arabidopsis thalianaCareno, D.A.Careno, D.A.(1), Assaf, C.H.(1), Eggermont, E.D.C.(2), Sanchez, S.E.(1), Yanovsky, M.J.(1)(1) Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires–Consejo Nacional de Investigaciones Científicas y Técnicas (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina. (2) Plant-Environment Signaling group, Department of Biology, Utrecht University, 3584 CH Utrecht, the NetherlandsAlternative splicing (AS) is a co-transcriptional gene expression regulatory mechanism by which one gene can produce many different transcripts. These different transcripts can encode for different protein isoforms, or change mRNA stability through nonsense-mediated decay or microRNA regulation. Increasing evidence suggests that AS plays a relevant role in many plant physiological processes such as seed germination, photomorphogenesis, and flowering. In Arabidopsis thaliana, light is one of the major environmental cues that triggers changes in splicing patterns. Two pathways have been proposed to mediate this response: one that depends on the action of sensory photoreceptors and another where a retrograde signal from the chloroplast travels to the cell nucleus and modulates splicing. The extent to which each pathway regulates splicing remains unknown. Phytochromes are red and far red light sensing photoreceptors that interact with several splicing factors. The Arabidopsis genome encodes for five phytochromes (PHYA-PHYE). Here, we used high-throughput RNA sequencing (RNA-seq) to evaluate the effect of a red light pulse on AS in light grown wild type (WT) plants and quintuple phytochrome mutants (phyQ). We found 633 splicing events regulated by red light in WT plants, which correspond to 438 genes. Only 22% of these events were also differentially spliced in the phyQ mutant. Also, the expression of multiple splicing factors was altered in the phyQ mutant. Given that expression patterns depend on the developmental stage, we performed a metaanalysis of several public available RNAseq datasets to dissect the role of phytochromes during germination, photomorphogenesis, and in response to shade. Overall, our results suggest that phytochromes are required for the fine tuning of AS in Arabidopsis throughout its life cycle but, to a large extent, light acting through other light signaling pathways plays a predominant role in the modulation of AS in light grown plants.splicing, red light, phytochromes, Arabidopsis
Soybean Seed Composition under Different Water ConditionsLopez, Emelí (1,2)Angelozzi, V (1); Antonelli, M (1,2); Alvarez Prado, S (1,2); Gerde, J (1,2).(1) Cátedra de Sistemas de Cultivos Extensivos-GIMUCE. Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental Villarino S/N, S2125ZAA Zavalla, Prov. de Santa Fe, Argentina. (2) IICAR – CONICET, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Campo Experimental Villarino S/N, S2125ZAA Zavalla, Prov. de Santa Fe, Argentina.In soybeans (Glycine max (L.) Merr.), water deficit during seed filling shortens the duration of this stage, thus reducing seed size. The impact of water deficit on seed composition differs according to the timing and intensity of drought stress as well as the genotype used. The objective of this study was to characterize the dynamics of soybean seed filling dissected in its main components: oil, protein and soluble carbohydrates under different water scenarios. The experiment was conducted in Zavalla, Santa Fe, Argentina (33°1 S, 60°53 W). Three commercial soybean genotypes with contrasting seed compositions (SYN 5X1; DM 40R16; DM 4619) were evaluated in environments with contrasting water availability: fully irrigated (IR), rainfed (RA) and water restricted (WR) between flowering (R1) and physiological maturity (R7). Average seed weight varied between 4.6 and 200 mg seed -1, while protein, oil and soluble carbohydrates varied from 1.5 to 78.8, 0.30 to 46.4 and 0.47 to 21.8, mg seed -1 respectively throughout the whole seed filling stage. The rate (0.25 to 0.44 mg °Cd -1) and duration of seed filling (297 to 695 °Cd) were affected by the environment (35 and 91% variation, respectively), as well as final seed weight (91% variation). Regarding seed composition, variation in final protein, oil and carbohydrates content was mainly driven by the environment through its impact over the filling duration, while the rate of accumulation showed a strong genotypic component for oil and protein. Finally, the rate of accumulation of soluble carbohydrates was independent of the genotype and the environment. Seed weight variation was mainly driven by the available water and the duration of the seed-filling period. In terms of composition, the genotype established the rate of accumulation of both oil and protein, while the environment determined their final content. However, none of the effects studied modified the rate of soluble carbohydrate accumulation.soybean, seed composition, water availability, seed filling
Integral analysis of morphophysiological variables associated with drought tolerance in Leptochloa crinitaDominguez, Deolindo L. E.Panasiti Ros, J. (1), Cavagnaro, J.B. (2), Cavagnaro, P.F. (3)(1) Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo. (2) Instituto de Biología Agrícola de Mendoza (IBAM), Facultad de Ciencias Agrarias, CONICET, UNCuyo. (3) Instituto Nacional de Tecnología Agropecuaria (INTA) E.E.A La Consulta, Mendoza, Argentina.Leptochloa crinita is a native forage grass occupying extensive arid and semi-arid regions in the American continent, and used for range grazing and revegetation of degraded lands. To identify drought-tolerant genotypes and possible underlying physiological mechanisms, this study investigated drought tolerance in 21 genetically diverse L. crinita genotypes under natural field conditions. The accessions were grown under irrigated (control) and drought conditions for 84 days after initiation of the drought treatment. Various morpho-physiological traits were monitored, including total-, foliage-, and root biomass yield, dry matter partitioning to individual plant organs, total leaf area, chlorophyll content, photochemical efficiency of photosystem II, stomatal conductance, and number of panicles per plant.

Broad and significant variation (p<0.001) was found among the accessions for all the traits. Three highly tolerant and three very sensitive accessions were identified as the most contrasting materials. Under prolonged drought conditions, the tolerant accessions were generally more productive than the rest for all the biomass yield components analyzed, and this was associated with a postponed and more attenuated decrease in variables related to the plant photosynthetic activity, such as stomatal conductance, chlorophyll content, and photochemical efficiency. In contrast to previous findings, our data indicate no direct relationship between drought tolerance and the level of aridity in the accessions natural habitats. Also, having low total and forageable biomass yield, or increased biomass allocation to the roots (i.e., lower foliage/root ratio), under optimal water availability, were not associated with greater drought tolerance. The drought-tolerant accessions identified are of value for future genetic research and breeding programs, and as forage for range grazing and revegetation in arid regions.
Trichloris crinita, drought stress, photoassimilates partitioning, biomass, stomatal conductance, photochemical efficiency
Drought stress effects on transgenic tobacco plants expressing maize NADP-ME under KAT1 promoter: trade-off between seed size, quantity, and survivalGuindon, María FernandaSaper, Carolina; Oitaven, Pablo Agustín; Olazarán Mainetti, Josefina Drincovich, María Fabiana; Müller, Gabriela LeticiaCEFOBI-CONICET, Fac. de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de RosarioDrought stress is a factor that affects morphological, physiological, biochemical and molecular plant attributes with adverse impact on plant productivity. Nicotiana tabacum transgenic plants expressing maize non photosynthetic NADP-ME in guard and companion cells under KAT1 promoter had shown enhanced water use efficiency.  To assess whether these plants could better cope with drought conditions, they were grown for 60 days and then irrigation was stopped for 30 or 45 days. Finally, plants were irrigated until the end of the cycle and total dry stems, leaves and fruits were collected. Transgenic lines had exhibited an accelerated flowering and producing mature seeds earlier than the WT under normal conditions. This accelerated development was also observed in plants exposed to 30 days drought treatment, transgenic lines produced mature seeds approximately 20 days earlier than the WT. Also, the number of seeds per fruit and seeds per plant was 1.7-2.9 times greater in the transgenic lines than in the WT in normal and after 30 days of drought treatment. While the WT was not able to survive after a 45 days drought, the transgenic lines showed almost the same number of seeds per fruit as after 30 days of drought. The 1000-seed weight of the transgenic lines decreases by 1.1-1.5 times compared with the WT, but due to the increase in the number of seeds of the transgenic lines compared to the WT, the seed yield (g per plant) of the transgenic lines is increased between 1.4- to 1.8-fold compared to the WT in both conditions. We analyzed the composition and size of the seeds to investigate the causes of the decrease in seed weight. Moisture, starch, triacylglycerol, and protein contents of transgenic and WT seeds were not significantly different, either under normal conditions or after recovery from 30 days drought. However, transgenic seeds were slightly smaller than WT seeds but this does not affect germination percentage.
Changes in Nicotiana tabacum stem morphology due to expression of NADP-malic enzyme in drought tolerant transgenic linesMüller, Gabriela LeticiaGuindon, María Fernanda (1); Oitaven, Pablo Agustín (1); Srebot, María Sol (2); Saper, Carolina (1); Olazarán Mainetti, Josefina (1); Drincovich, María Fabiana (1)(1) CEFOBI-CONICET, Fac. de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (2) Área Farmacobotánica, Fac. de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de RosarioNADP-malic enzyme (NADP-ME) has been suggested to play important roles in diverse stress responses in plants. The integration of the plastidic non-photosynthetic NADP-malic enzyme from Zea mays into the Nicotiana tabacum genome using KAT1 promoter, which drives expression to both guard cells and companion cells of sieve elements has generated lines with enhanced yield and earlier flowering under normal and drought conditions. The role of stem in these drought-tolerant plants has hardly been studied, even though it plays a vital role transporting water and other products. In this work, light microscopy analysis of stem sections of tobacco plants revealed morphological differences in the distribution of different tissues between the lines. Under normal condition stem area occupied by the pith was greater in transgenic lines, while stem area occupied by the xylem was smaller compared to the WT. The pith occupied between 20 to 31% in transgenic lines and 13% in WT, and the xylem occupied 8 to 10% and 15%, respectively. After 30 days of drought the distribution changed, but the area occupied by the pith was still greater in transgenic lines. About 6% of the WT stem area was occupied by the pith, while about 35% was occupied by the xylem. In transgenic lines, 14 to 24% of the stem area was occupied by the pith, and 30 to 32% by the xylem. We test if these variations were related to water and sugar content. There was no difference in moisture content between WT and transgenic stems under normal conditions and after 30 days of drought; however, transgenic lines showed higher glucose values than WT (between 3.8 and 4.7 against 3.6 mg glucose/g stem). These results suggest that NADP-ME expression causes changes in tobacco stem morphology that may improve plant productivity, especially under drought conditions.
Spatial and temporal variability of single and double soybean yields across ArgentinaGuido Di MauroFernandez-Long, M.E. (2), Alvarez Prado, S. (1,3)(1) Cátedra de Sistemas de Cultivos Extensivos-GIMUCE, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Argentina (2) Facultad de Agronomía, Departamento de Recursos Naturales y Ambiente, Cátedra de Climatología y Fenología Agrícolas, Universidad de Buenos Aires, Buenos Aires, Argentina (3) IICAR - CONICET, Concejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, ArgentinaIn Argentina, besides the historical expansion of single soybean crop (SC), part of the recent increase in area has been driven by increasing cropping intensity, with 30% of the area currently sown after wheat (‘double crop soybean,’ DC). Although the productivity of DC is lower than that of SC, the use of DC improves resource use efficiency or reduces production risks at the farm level. Despite these advantages, the proportion of DC has remained unchanged over the last few years. Our objectives were: i) to quantify the yield difference between SC and DC yields, ii) to explore its spatial and temporal variability, and iii) to identify environmental drivers behind these yield differences. Our analysis estimated the relationship between SC and DC yield (SC divided by DC, hereafter called Yr) using public records for Argentina. A database of yield, meteorological and soil information was constructed. The spatial resolution of the base corresponded to the county level, covering the 2000–2017 growing seasons. We explored the spatial variability of the Yr in Argentina using the inverse distance-weighted interpolation method. In addition, we evaluated Yr temporal variability using a previously published method for estimating yield trends across years. Residuals of the linear regression between Yr and years were used to describe Yr temporal stability and were explained using environmental factors. Yields ranged from 2248 to 3300 and 1400 to 2500 kg ha-1 for SC and DC, respectively. The average SC and DC yields were 2717 and 1918 kg ha-1, respectively. The average Yr was 1,30; ranging from 1,15 to 1,70. The variability in Yr showed a spatial pattern, allowing the identification of areas with different values. In general, restrictive environments (North/West regions) showed lower Yr than high-yielding environments (Central region). Our approach identified conditions with a low Yr, suggesting that DC is an interesting alternative for agricultural intensification.yield trend, residuals, yield ratio, crop intensification
Frost tolerance in vegetative stages and allelic characterization in wheatSerrago, R.A. (1 y 2)Comacchio, J.E. (1); Vanzetti, L.S (2 y 3); Miralles, D.J. (1 y 2)(1) Facultad de Agronomía, UBA. (2) CONICET. (3) EEA Marcos Juárez, Instituto Nacional de Tecnología Agropecuaria (INTA).There is genotypic variability for frost tolerance in wheat during vegetative stages. Winter genotypes, which have cold requirements to heading, have recessive alleles in the three homologous genes of Vrn-1 (vrn-A1, vrn-B1 and vrn-D1). The existence of a single dominant allele in any of the Vrn-1 homologues imposes a spring phenotype, with little or no cold requirements for heading. Winter materials appears to be more tolerant to frost during vegetative stages, although this was never verified in depth in Argentine genotypes. We carried out experiments using 25 commercial wheat genotypes in growth and frost simulation chambers. Sowing was carried out in a greenhouse and at DC12, the seedlings were transferred to an acclimatization chamber for approximately 30 days (6°C and approx. 200 µmol/m2/s). Once the acclimatization period was completed, the seedlings (DC14) were subjected to the different frost treatments for 2 hours (T=0°C; -3.5°C; -6.5°C; -8.5°C and -11°C). The number of living/dead plants after each frost treatment was determined. A logistic function of three parameters was fitted for this variable and the LT50 (°C) was calculated. LT50 (°C) represents the temperature at which 50% of the seedlings die. The results showed that 2 winter genotypes were the most frost tolerant (LT50 was not possible to determine in those genotypes, because the frost treatments imposed in this experiment were not sufficient to cause the death of 50% of the population). Among the genotypes where the LT50 could be determined, the winter genotypes (vnr-A1/vnr-B1/vnr-D1) were the most frost tolerant with an average LT50 of -8.6°C (range of -7.3° C/-10.8°C), while the most susceptible genotypes were the spring for the dominant allele in A1 (Vrn-A1) with a mean LT50 of -7.3°C (range -6.4°C/-8.2°C). Finally, the spring genotypes carrying the recessive allele in A1 (vrn-A1) had an intermediate behavior.plant physiology, frost tolerance, genes, Vrn1
Role of PHYTOCHROME INTERACTING FACTOR 7 in the rapid response to elevated ambient temperature and shade in ArabidopsisGermán MurciaJorge CasalFundación Instituto Leloir, Buenos Aires, ArgentinaWarm temperatures within the physiological range or low red/far red light (shade condition) can selectively increase or decrease the growth of different plant organs. These changes lead to modifications in plant architecture, a process known as thermo- and photomorphogenesis, respectively. Thermo- and photomorphogenesis occur simultaneously in a dense canopy of crop species in the current context of global warming. The transcription factor PHYTOCHROME INTERACTING FACTOR 7 (PIF7), which was previously characterized as a key player of the shade avoidance response, was recently described as a plant temperature sensor. In this sense, warmth-induced changes in the RNA hairpin present at 5´-untranslated region of the PIF7 transcript favor its translation, increasing PIF7 protein abundance. In addition, PIF7 binds the promoters of auxin biosynthesis genes to increase auxin levels, promoting stem and petiole growth. In this study, using a genetic approach, we found that PIF7 is necessary for the normal growth of Arabidopsis thaliana hypocotyls in shade or/and warm conditions. Furthermore, we observed a positive interaction between warm and shade cues in the Col-0 wild type accession. Both treatments rapidly (10 min) enhanced PIF7 protein accumulation compared to white light 20ºC control plants to then decrease. Reaching the lowest values at 24 h post treatment. However, this transient increment of PIF7 protein was sufficient to promote hypocotyl growth for the next 3 days. Interestingly, the rapid increase of PIF7 protein was only observed when plants were treated with shade or/and warm temperature during the morning but not in the afternoon, highlighting a possible circadian-regulated accumulation of PIF7 under these conditions. We demonstrate that PIF7 is important for the rapid response of increased ambient temperature and shade.PIF7, WARM, SHADE, GENETICS, ARABIDOPSIS, GROWTH
Validation of candidate genes associated to earliness per se, on chromosome 5D of bread wheatFlorencia I. PozziPozzi, Florencia I. (1); Ghione, Celina E. (2); Helguera, Marcelo (3); Lombardo Lucio A. (2) y Felitti, Silvina A. (1)Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR). CONICET-UNR.In bread wheat, earliness per se (Eps) can be defined as the residual variation in flowering time once the photoperiod and vernalization requirements have been satisfied. It has been shown that Eps genes can affect the yield of this cereal. The mapping of Eps in five environments revealed the existence of an unprecedented quantitative trait loci (QTL) QEps.imj-5D1 located on chromosome 5D, where the region most likely to find the candidate gene has a size of 26.25Mb with 391 genes annotated. In a previous work, carried out from the whole exome sequencing (MyBaits® expert panel-Arbor Biosciences) of the parent cultivars BioINTA 2001 (B01, early-heading) and Baguette Premium 11 (B11, late-heading) of contrasting phenotypes for Eps, 4 candidate genes were detected: TraesCS5D01G362700, TraesCS5D01G380900, TraesCS5D01G393200 and TraesCS5D01G401000. The objective of this work was to develop primers to validate the set of candidate genes proposed by High Resolution Melting Analysis (HRMA). The primers were developed with primer3web 4.1.0 (https://primer3.ut.ee/), the real-time PCR was performed with the CFX Maestro 1.1 software, and the data were obtained with the Precision Melt Analysis 1.3 software. Four technical replicas of each genotype were used (260 ng/μl of DNA). The markers developed allowed the differentiation between the parental B01 and B11, where the replicas of each parent are grouped into 2 different clusters. In addition, for the TraesCS5D01G401000 marker, progress was made in the differentiation between B01, B11 and artificial heterozygotes. Also, a mutant of B11 (MutP), characterized phenotypically as early-heading, grouped with B01. That is, 3 clusters were obtained: 1- replicas of B01 plus those of MutP, 2- replicas of F1Ar and 3- replicas of B11. The results obtained allow us to continue advancing in the validation of the set of proposed candidate genes by incorporating into the analysis a population of NILs previously developed by the research group.bread wheat, flowering time, breeding, molecular markers, HRM
Prediction of preharvest sprouting susceptibilty in malting barleyMaximiliano OrtizBenech Arnold, R. L.Instituto de Investigaciones Fisiológicas y Ecológicas vinculadas a la AgriculturaPre-harvest sprouting leads to an imminent loss of seed viability, affecting the quality of malting barley crops. Knowing that the temperature during grain filling has an effect on dormancy release rate, we looked for a correlation between temperature experienced by the crop on different thermal time intervals during grain filling, and the susceptibility to suffer pre-harvest sprouting, estimated as a germination index (GI) measured near harvest maturity. Two barley cultivars (Overture and Yanara) were sown on different dates over 2-year period for generating variability in the thermal environment during grain filling. Base temperatures (Tb) values for the grain filling period were unknow for these cultivars. Tb values were iteratively calculated by fitting least squares until no improvement in r2: they were 3 and 7°C for Overture and Yanara respectively. The period from pollination to physiological maturity was adjusted to a thermal time (TT) scale, which was then arbitrarily divided into different intervals. Mean air temperature within each interval and for the whole filling period was calculated for the different sowing dates. Dormancy release pattern was followed by determining a GI measured throughout grain filing and maturation.  We found a single sensitivity thermal time window for each genotype in which a significant (p<0.001) positive correlation was found between GI of grains with 10-20% moisture content (GI 10-20%) and mean temperature within TT interval (TmTT). A simple regression model explained the relationship between GI10-20% and TmTT. GI10-20% is a good estimator of the susceptibility to pre-harvest sprouting. We generated a predictive model for each cultivar, which can be instrumental to anticipate susceptibility to sprouting due to untimely exit from dormancy, which might lead to decide an early harvest in case of a forecast of rain.   Malting barley, dormancy, Pre-harvest sprouting, window sensitivity
Proteomic aspects of Ascochyta rabiei-Cicer arietinum interaction related to defense mechanisms.Carla GuzzoCrociara C.S (1); Vaghi G (1); Valetti. L (1); Guzzo M.C (2); Diaz S (3); Iglesias J (4) ; Pastor S.E (1)(1) IPAVE-UFYMA, CIAP, INTA-CONICET; (2) IFRGV-UDEA, CIAP, INTA-CONICET; (3) CEPROCOR; (4) EEA INTA Pergamino-UNNOBA.Chickpea blight, a fungal disease caused by Ascochyta rabiei, is the most damaging disease in chickpea fields worldwide. Since its first report in Argentina in 2012, has caused yield losses up to 100%. The exploratory study of the proteomics in the plant-pathogen interaction could be a potential tool to identify candidate proteins to improve chickpea defense responses against Ascochyta rabiei. Thus, they could be helpful to identify candidate genes and their further selection in chickpea genetic improvement programs. This work was aimed to find some differentially regulated proteins related with chickpea defenses in the plant-pathogen interaction. A susceptible chickpea genotype, Chañaritos S-156, and virulent isolated of Ascochyta rabiei RCB were used for this assay. A sample of three independent total proteins extractions were obtained of each treatment: inoculated vs non inoculated plants. The extracts were analyzed by Free label Quantification. More than 900 proteins were identified in each sample. Differentially expressed proteins were determined through with a student test (T-test), these results are represented in a volcano plot made in the Perseus software using p=0.05 as a cut-off value. Volcano plot shows 33 proteins significantly upregulated, and 80 proteins downregulated in the inoculated condition vs. non inoculated. Of those up-regulated, 24 have been cited before as related to plant defenses to biotic stresses and 15 of them belong to PR proteins. This is the first attempt to the understanding at proteomic level on the chickpea blight pathosystem in Argentina. It contributes to the understanding of Ascochyta rabiei-Cicer arietinum interaction and can contribute to identifying key factors for chickpea genetic improvement.

Financiamiento: Proyectos INTA: I090 y PD I083; Fundación ArgenINTA.
Chickpea, ascochyta blight, pathogen-plant interaction
A study of the complex I mitochondrial carbonic anhydrase domain in A. thalianaBalestieri, Nehuen (1)Marchetti, F. (1); Pagnussat, G. (1); Zabaleta, E. (1)(1) Instituto de Investigaciones Biológicas, IIB, Universidad Nacional de Mar del Plata, UNMdP, Argentina.Carbonic Anhydrases (CAs) are metalloenzymes that catalyze the reversible reaction CO2 + H2O ⇌ HCO3- + H+. CAs are present in all living organisms, and there are eight different types (α-, β-, γ- δ-, ζ-, η-, θ-, and ι-CAs) that have evolved convergently, differing in their active sites and amino acid sequences. The plant mitochondrial complex I contains a special, ancient domain composed of gamma-type carbonic anhydrases, known as the γCA domain.

In Arabidopsis, there are three genes encoding three γCAs (γCA1, γCA2, and γCA3), and two less conserved genes called γCA-Like (γCAL1 and γCAL2). The domain is composed of heterotrimers consisting of two γCAs and one γCAL protein. Mutant plant lines lacking the γCA2 subunit exhibit a molecular phenotype with a 80% reduction in the amount and activity of complex I, while double mutants γca1γca2 and γca1γca3 display delayed germination with no complex I. Current evidence suggests that these subunits may be specialized in different developmental stages. The γCA1 and γCA3 subunits are abundantly expressed during early embryo development. In late embryos and adult plants, γCA2 predominates while the expression of γCA1 is lower.

This study investigates the role of the γCA1 protein expressed under the γCA2 promoter in γca2 null mutants. The aim is to explore the potential complementation of the γCA2 deficiency through the specific expression of γCA1 in late embryogenesis stages and adult plants (using the γCA2 promoter). Preliminary results show that the mentioned construct is able to partially restore complex I deficiency in leaves of adult γca2 mutant plants.
molecular biology, plants, mitochondria, gamma carbonic anhydrases, complex I
Effect of the delay in sowing date on the content and quality of arabinoxylans in corn (Zea mays, L.) and its relation with kernel hardnessLaserna, María Paula (1,2,4)González Belo, R.(2,3); Cerrudo, A.(1,2,4); Izquierdo, N. (2,3,4)(1) IPADS, Balcarce (INTA-CONICET), (2) Facultad de Ciencias Agrarias, UNMdP. (3) IIDEAGROS, FCA, UNMdP. (4) CONICETThe post flowering environment influences maize grain quality, mainly in terms of kernel hardness, starch and protein contents and composition. The content and quality of dietary fiber has recently become a trait of interest, however, it is still unknown how these polysaccharides are affected by the post- flowering environment. Additionally, it is unknown whether their quantity and quality impact on the endosperm hardness. The aim of this work is to characterize the impact of the delay in sowing date on the quantity and quality of the arabinoxylans (component of the dietary fiber), as well as their relationship to variations in kernel hardness.

Two field experiments were carried out in Balcarce, assessing two sowing dates on a semident maize hybrid. Temperature and radiation during the critical period and grain filling period were recorded, and potential source and source/sink ratio were estimated in order to characterize the post flowering environments. At physiological maturity, endosperm hardness (coarse-to-fine ratio) and the composition of the grains was analyzed. Total arabinoxylan percentage (TOTAX%) and their degree of substitution, quantified as the arabinose to xylose ratio (A/XTOTAX) were analyzed by gas chromatography.

Grains with the lowest TOTAX% also presented the lowest kernel hardness and were the ones that had experienced the lowest values of potential source during the grain filling period. Besides, A/XTOTAX decreased as the TOTAX% was higher, although the regression analysis was not significant (p= 0,1). However, the variation found in A/XTOTAX could not be related to the variation in kernel hardness nor potential source during grain filling period.

According to our results, TOTAX% is negatively affected by poor environments during grain filling period and their variation can explain part of the variation in kernel hardness, rather than their A/X ratio. Further studies should be performed in order to better explain these relationships.
maize, kernel hardness, arabynoxylan, grain quality
Photoperiod sensitivity and spike fruiting efficiency as alternatives to increase wheat yield potentialFernanda G GonzálezPretini, N. (1); Perez-Gianmarco, T. (2); Vanzetti, L.(3)(1) EEA Pergamino, INTA, Argentina. (2) CITNOBA, Argentina. (3) EEA Marcos Juárez, INTA, CONICET, Argentina.Breeding cultivars with higher yield potential (the yield of an adapted cultivar without water or nutritional restrictions and free of biotic stresses) is an alternative to improve wheat production in a sustainable way. Photoperiod sensitivity during stem elongation has been proposed a long time ago as a potential trait to increase duration of that phase, which would result in higher spike growth and grains, the main determinants of yield potential. Photoperiod sensitivity could also help to adapt new cultivars to warming temperatures associated to climate change. How the known genes associated to photoperiod sensitivity control development of the different phases of the wheat cycle is necessary for assessing their usefulness in breeding. More recently, the spike fruiting efficiency (grains per gram of spike dry weight at anthesis) has been proposed as a trait to increase grain number and yield potential. The physiological, and particularly, the genetic bases determining the trait need to be understand to use it as selection criteria in breeding programs. The state of art of both traits will be discussed during the oral presentation at the Vegetative and Reproductive Development Symposia of the RAFV 2023.WHEAT YIELD, PHOTOPERIOD SENSITIVITY, FRUITING EFFICIENCY
Evaluation of the effect of TuMV infection on drought tolerance and water management at the whole plant level in ArabidopsisCarlos A. Manacorda (1)Cáceres, P. (2), Sutka, M. (2), Baroli, I. (2), Amodeo, G. (2), Asurmendi, S. (1)(1) Instituto de Agrobiotecnología y Biología Molecular (IABIMO, INTA-CONICET), Hurlingham, Argentina. (2) Departamento de Biodiversidad y Biología Experimental (DBBE, FCEyN-UBA) and Instituto de Biodiversidad y Biología Experimental Aplicada (IBBEA, UBA-CONICET), Buenos Aires, Argentina.The assessment of the interaction effect between different types of stresses simultaneously affecting plants has received great interest in recent years, since it is considered that it represents in a more realistic way the conditions that crops must face in the field. In the present work, the effect that TuMV infection has on the water balance in Arabidopsis was evaluated both at the rosette level (stomatal conductance, instantaneous dehydration rate, relative water consumption, RWC, osmolarity) and at the root level (root hydraulic conductivity, osmolarity). These physiological measurements were accompanied by anatomical measurements to estimate the relative growth under infection in different organs. In addition, survival measurements were carried out to estimate putative changes in drought tolerance produced by the viral infection. TuMV was found to cause profound changes in water management at both the foliar and root levels. In addition, drought competition experiments showed that TuMV lowers drought tolerance in Arabidopsis, evidencing a negative synergistic effect for the plant under the interaction of both stressors when they act simultaneously.Turnip Mosaic Virus, drought, Arabidopsis, root hydraulic conductivity, osmolarity, water management, combined stresses
Effects of flooding on the growth of different cultivars of cassava (Manihot esculenta Crantz) plants grown in greenhouse conditionsMedina, R.D. (1,2)ver documento adjuntover documento adjuntover resumen adjuntoCassava, dry matter, flooding, growth, tuberous roots
Characterization of genes relevant to the biological functionality and transcriptional regulation of the ZmNADP-ME3 malic enzymeSosa Maximiliano MartinNasello, F. (1); Sosa, M. (1); Gismondi, M. (1); Saigo, M. (1)Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI‑CONICET), Universidad Nacional de Rosario (UNR), Rosario, Argentina.ZmNADP-ME3 is a maize NADP-dependent malic NADP-dependent enzyme that catalyzes the oxidative decarboxylation of malate and is expressed almost exclusively during kernel development and in response to ABA hormone-mediated stresses. Although the ZmNADP-ME3 transcript is found at high levels in embryo and endosperm, the enzyme activity was significantly higher in embryos. In addition, it could be verified that the activity is maximal 20 days after pollination. The presence of ZmNADP-ME3 was also studied by Western blots. Although the reaction it catalyzes is well characterized, its biological role is still unknown. To further study the function of ZmNADP-ME3, a meta-analysis of genes co-expressed in different tissues and stages of maize kernel maturation was performed. As a result, genes strongly linked to ZmNADP-ME3 were identified that could provide clues to the processes in which this malic enzyme participates. In addition, we searched for conserved motifs in the promoters of the co-expressed genes to determine whether they respond to a common signalling pathway. These results, together with those previously obtained on transcription factors that bind to the ZmNADP-ME3 promoter, provide relevant information on the expression networks in which the ZmNADP-ME3 protein is involved.Malic Enzyme, Meta-analysis, Transcriptional regulation, Expression networks
Free polyamines content and oxidative response during cold storage of sunburn applesVita L. I.(1)Spera, N. (1,2); Colavita G.M (1)(1) Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue, subsede IBAC (CONICET- UNCo) Ruta 151, km 12, Cinco Saltos, RN. (2) Sede Andina, Universidad Nacional de Río Negro, El Bolsón, Río Negro, Argentina.High solar radiation causes an imbalance between the production of reactive oxygen species and antioxidant mechanisms in apple fruits, leading sunburn development. Polyamines (PAs), such as Putrescine (Put), Spermidine (Spd), and Spermine (Spm), participate in the antioxidant response of plants under oxidative stress. The aim of this work was to study PAs evolution, oxidative metabolism, and sunburn damage in 'Cripp's Pink' apple fruit during cold storage. At harvest, fruits with mild sunburn skin (S1) and healthy skin (S0) were selected and stored under conventional cold storage at 0±1°C; RH 95%. Put, Spd, and Spm levels, lipid peroxidation (TBARs), antioxidant capacity (DPPH), sunburn scald (SS), and superficial scald (SupS) were evaluated on the skin of each sector at harvest and at 90, 120, 150, and 180 days of storage. At harvest, S1 showed 26.5% more PAs compared to S0. However, during cold storage, S0 increased its PAs content by 109.6%, while S1 remained unchanged. During cold storage, Put in S0 exceeded S1 by 131%. At harvest, Spd and Spm were 88.6% and 34.1% higher, respectively, in S1 compared to S0 and increased proportionally during storage. TBARs showed no differences between S0 and S1 at harvest and low temperatures promoted a 52.3% increase in both tissues. S1 exhibited higher antioxidant capacity at harvest, which remains during storage. After 150 days, 10% of the fruits S1 showed mild SS, and after 180 days, 23% showed moderate SS, while fruit S0 doesn´t develop SupS. The higher antioxidant capacity and Spd and Spm in S1 could be associated with the low occurrence of SS. The increase in Put, Spd, and Spm in S0 during cold storage possibly contributed to the absence of SupSMalus domestica, antioxidants, scald, oxidative metabolism
Influence of the epiphyte Bacillus velezensis HIII11 isolated from strawberry on the metabolism of Arabidopsis thaliana cell wallHirsch M.Burges, P.L. (1); Wyss, B. (1); Villarreal, N. (1); Marina, M. (1)Instituto Tecnológico Chascomús (INTECH, CONICET-UNSAM), Argentina.The Bacillus genus comprises several bacteria recognized as biological control agents and/or plant growth-promoting bacteria. The reinforcement of the cell wall of the host plant is one of the benefits reported for this genus. The epiphyte HIII11 previously isolated from strawberry leaves (Fragaria x ananassa, Duch) showed the ability to promote the growth of A. thaliana plants and to inhibit the in vitro growing of Botrytis cinerea and Rhizopus stolonifer. In the present work, the sequencing of the 16S rRNA, recA, and recN genes, identified HIII11 as Bacillus velezensis. Therefore, we decided to evaluate whether HIII11 generates changes in the cell wall of A. thaliana plants. Col-0 plants previously inoculated with the bacteria and control plants (mock-inoculated with MgCl2) were used. We isolated cell walls as alcohol-insoluble residues (AIR). The amount of AIR was higher in HIII11-inoculated plants compared to the control. In addition, the growth capacity of B. cinerea and R. stolonifer on agar plates containing the extracted cell walls as the only source of nutrients was analyzed. Interestingly, we observed that the growth of both pathogens was lower on plates containing AIR from plants inoculated with HIII11. Besides, through Real Time PCR we measured the expression of genes related to the plant cell wall metabolism. As for the pectin metabolism, we did not observe changes in the expression of a putative polygalacturonase (AtPG1) compared to the control. However, the relative expression of pectin methylesterase (AtPME3) increased in plants inoculated with the epiphyte. In turn, HIII11 downregulated the expression of AtAra1 and AtβGal, which encode an α-arabinofuranosidase and β-galactosidase, respectively (related to side-chain metabolism). As regards hemicellulose metabolism, a downregulation of an expansin (AtExp8) was observed. All the results suggest that B. velezensis HIII11 could promote cell wall reinforcement in A. thaliana and encourage further study.Bacillus velezensis, Arabidopsis thaliana, Botrytis cinerea, Rhizopus stolonifer, plant cell wall, strawberry
Growth, yield and water use efficiency of lanceolate and ovate soybean isolines grown under rainfed and irrigated field conditionsBianchi, Julieta SofíaPalomino Martini, T.K.; Islas, M.; Gómez, R.L.; Quijano, A. & Bianchi, J.S.*Laboratorio de Eco-Fisiología Vegetal (LEFIVE) - IICAR-CONICET/UNR. Facultad de Ciencias Agrarias, Universidad Nacional de Rosario (UNR). Parque Villarino S/N, 2125, Zavalla, Santa Fe, Argentina.Drought is by far the main environmental factor contributing to yield losses in soybean. Thus, the exploration of different approaches to mitigate this hardship is essential to guarantee crop production. Previous reports shown that soybean canopies with lanceolate leaflet shape (L) have lower leaf area index (LAI) but similar crop growth rate (CGR) and yield compared to ovate leaflet shape (O). Therefore, a decrease in crop evapotranspiration (ETc) and/or an increase in water use efficiency (WUE) could be expected in L soybeans. This hypothesis was evaluated using L and O soybean isolines in rainfed (R) and irrigated (I) conditions, sown during 2021/22 growing season at the Fac. de Cs Agrarias, UNR. Irrigation was done at regular intervals of 10 days until R3. Physiological parameters were analyzed during the vegetative (Ve) and early reproductive (ERep) period, while WUE and yield and yield components were analyzed at harvest. Irrigated treatments received 150 mm more than rainfed leading to significant differences in water availability and ETc (p<0.05), without differences between L and O isolines. Also, differences were detected at leaflet shape level, while no interaction between leaflet shape and irrigation was found. During the Ve and ERep, L isolines attained similar CGR tan O isolines, despite their lower LAI, due to an increase in the net assimilation rate. L isolines showed higher CO2 net assimilation, stomatal conductance and SPAD (p<0.05). At harvest, L isolines yielded more than O due to a higher seed number (21%; p<0.001), seed per pod (13%; p<0.001) and pod number (8%; ns). Total biomass (TB), harvest index and WUE were also greater in L isolines (p<0.05). Since no differences were detected in ETc in L isolines, the increase in WUE was due to TB. Results demonstrate that L isolines have greater photosynthetic efficiency and yield than O isolines regardless water supply, offering a potential for improving productivity under different environments.Soybean, Water Stress; Leaflet Shape, Crop Growth, Yield.
Zinc, aminoacid and algae extract application seed treatments effect on growth and yield of Triticum aestivum with different predecessor herbicides.Arevalo, E. S. (1,2,3)Michel A. (1); Ludi Barzante L. (1); Foti, M. N. (1) Chajud S. (1)ver documento adjuntover resumen adjuntoTriticum aestivum, biostimulants, seed treatments, herbicide persistence.
Unveiling the BAG Protein Family in Physcomitrium patens: identification and functional characterizationAlexandra Castro (1)Saavedra, L. (2,3); Silva., S (1); Vivas, A. (1); Vidal, S. (1)ver documento adjuntover documento adjuntover adjunto
Soybean seed coat: a key intermediary between maternal nutrient supply and embryonic metabolismJuan Ignacio ZucchettiMercedes Barat Carnino (1); Emelí Lopez (2); José A. Gerde (3); Lucas Borrás (4); Mariana Saigo (5); Mariel C. Gerrard Wheeler (6)Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI) CONICET-UNRA global problem in improving soybean (Glycine max) genotypes is the negative correlation observed between protein and oil contents in mature seeds, as well as an opposite relationship between protein concentration and yield. The soybean seed coat is a specialized tissue that protects and nourishes the embryo during its development, in contact with the maternal vasculature. However, little is known about the functioning of this structure during seed maturation, specifically in the process of protein and oil synthesis in embryo cotyledons, which are accumulated the storage compounds that give value to the seed.

In this study, we conducted a comparative analysis of soybean early maturing seed coats from genotypes with contrasting levels of protein and oil. To identify key processes that could act differently, seed coats were collected from experimental related high- and low- protein lines at R5 stage, and subjected to proteomics and metabolomics analyses.

Our results revealed increased abundance in proteases and proteins related to the ubiquitin-proteasome system in the high-protein line. Additionally, higher levels of most amino acids were detected and enzymes involved in amino acid metabolism, such as glutamine synthetase and aspartate aminotransferase were also more abundant in this line. These findings are suggesting differences between contrasting lines en terms of temporary storage and nitrogen remobilization at the seed coat that could be determinant factors for soybean seed quality.

Soybean seed coat, metabolism, protein and oil
Silencing of a CCT domain containing protein in tomato plants leads to increased abiotic stress tolerance.Diego Javier RenziZayas, A.(1); Sossi, M. L. (1); Zanor, M. I. (1)Instituto de Biología Molecular y Celular de Rosario, IBR.A group of genes that encode proteins with a conserved motif called CCT (for CONSTANS (CO), CONSTANS-like (CO-like), and Timing of CAB expression1 (TOC1)) participate in the regulation of flowering and circadian rhythm. Recent progress in the characterization of CCT family genes show that they regulate characters like plant growth, development, and stress tolerance. The CCT proteins include those called CMF (CCT motif factor) having a single CCT domain. Our results indicate that in tomato, there are 7 putative SlCMF genes and However, to the best of our knowledge none of these genes have been yet characterized. In this work we present the characterization of one selected CMF gene using transgenic tomato (S. lycopersicum) plants (cv. Micro-Tom). We also analyzed abiotic stress responses of the lines. Plants with reduced levels of the gene showed increased tolerance to water deprivation and oxidative stress. Although the potential functional mechanisms of the gene remain unclear, our current study results indicate that this protein has great potential in agricultural applications.CCT proteins, tomato, abiotic stress
Carotenoid rich tomato fruits due to overexpression of an endoplasmic reticulum specific sHSP isoform.Aldana ZayasRenzi, D.J. (1); Sossi, M.L. (1); Zanor, M. I. (1)Instituto de Biología Molecular y Celular de Rosario, IBR.Tomato (Solanum lycopersicum) is the second most important vegetable crop worldwide after potato and its production is destined either for the fresh fruit market or the processed food industries. To extend the commercialization period of fresh tomato, fruits are stored at low temperatures after harvest. Previous analysis of the fruit transcriptome after cold storage (Gonzalez et al, 2019) have shown an up-regulation of the transcription of genes encoding antioxidant enzymes and low molecular weight (< 45KDa) chaperon-like proteins or small heat shock proteins (sHSPs). Plants are unique in expressing in a cell a multiplicity of cytosolic sHSPs and specific sHSPs targeted to the plastids, the endoplasmic reticulum (ER) and the mitochondria (Siddique et al. 2008). sHSPs play an important role in thermotolerance as their transcripts exhibit a dramatic up-regulation when the plant is subjected to temperatures above optimum growth values. Beside their roles in stress tolerance, they play major roles in development as some of them have been detected in special plant organs, such as maturing pollen, germinating seeds, developing embryos, and growing fruits. In this study, we have generated and characterized transgenic tomato plants overexpressing and silencing the sHsp21,5-ER gene using a fruit specific promoter. Our results suggest that sHsp21,5-ER positively influences the accumulation of the pigment β-carotene in fruits even after chilling. Ripe tomato fruit color is the result of chlorophyll breakdown and carotenoid accumulation. Color is considered one of the most important quality attributes of tomato fruit for consumer acceptance and pigment composition contributes to the fruit nutritional value. Overexpression of an endoplasmic reticulum specific sHSP isoform leads to nutritional valuable fruits.Solanum lycopersicum, sHSPs, β-carotene
Firsts approaches in the development of phenological models and zonification for walnut (Juglans regia) production in ArgentinaGallo, Agustina EugeniaGallo, A. (1); Calderón, F. (2); Calvo, F. (2.1); Calahorra, A. (3); Robles, J. (4); Trentacoste, E. (5)(1, 2) Estación Experimental Agropecuaria Junín, INTA. (2.1, 3, 4) Instituto de Agricultura Sostenible en el Oasis, Universidad Nacional de Chilecito. (2, 2.1) CONICET. (2.1, 3, 4) Estación Experimental Agropecuaria Chilecito, INTA. (5) Estación Experimental Agropecuaria La Consulta, INTA.In the last decades, walnut consumption has increased worldwide thanks to their nutritional properties1. Following this trend, walnut cultivated area has expanded in Argentina (mainly in Catamarca, Mendoza and La Rioja) reaching 18235 ha in 20212. Walnut quality is determined by nut and kernel size, kernel color, oil content, and kernel-to-nut weight ratio (KNR). These features depend on the variety, but environmental conditions, management and their interactions play a key role3. Temperature is the main driver of plant phenology and determines the occurrence of reproductive stages that impact on production. As temperature increases are expected in Argentina4, walnut production and quality may be threatened in the future. The objective of this work was to assess fruit quality in walnut orchards, covering a latitudinal-altitudinal gradient along western Argentina. Walnut orchards with cv. Chandler and similar management were chosen in Mendoza (Agua Amarga, Chacón, La Consulta, Los Sauces and San Martín) and La Rioja (Santa Florentina and Tilimuqui). These 7 sites were from 620 to 1700 masl, and had an average difference of 5 ºC in December-April mean, maximum, and minimum temperatures. At harvest, we measured nut size and dry weight (dw), kernel size, kernel dw and KNR. We found that nut size and dw were not affected in the warmer sites. Indeed, the fruits were larger in the warmer sites in La Rioja. However, kernel dw was lower in San Martín, which had the higher autumn temperature. This suggests that nut development was not affected by higher temperatures, but kernel fill decreased5. KNR was above 40% in all sites, except in Los Sauces. Kernel dw correlated with kernel size and nut dw for all sites, confirming a strong genetic effect in fruit characteristics. These results are a first approach to understand the influence of environment in walnut fruit development and maturity. We sight to contribute to walnut phenological models and zonification in Argentina.plant phenology, zonification, fruit quality, walnut
Plasmodesmata and callose interplay in the regulation of plant root developmentYoselin Benitez-AlfonsoGerman, L.; Kirk, P; Amsbury S.Centre for Plant Sciences, University of Leeds. UKIntercellular communication via plasmodesmata (PD, channels connecting the cytoplasm of neighbouring cells) regulates the spreading of molecular signals including RNAs, proteins, sugars and hormones. In 2018, we reported the role of PD mediated transport in the formation of legume-rhizobia nitrogen-fixing symbiosis impacting root development in poorly fertilized soils (Gaudioso-Pedraza et al., 2018). We identified callose-degrading enzymes induced during nodule development to facilitate rhizobia infection and root colonization. Callose is a beta-1,3 glucan cell wall component that deposits at PD sites restricting its cytoplasmic aperture and symplasmic transport.  Additional evidence supporting a role for callose and PD in the regulation of nodulation in nitrogen repleted conditions, in drought/salinity stress and in root interactions with other symbiotic microbes are presented. I also introduce our efforts to understand the structural properties of callose at and outside PD/ pit fields and discuss the implications of our findings in light of the context presented by different cell walls.plasmodesmata, intercellular communication, plant stress responses, models
Functional analysis of Ilex paraguariensis metallothionein genes in transformed Lotus tenuis plants subjected to abiotic stress: Preliminary resultsAlvarez, M.Y. (1,2)Espasandin, F.D. (1,2) ; Acevedo, R.M. (1,2); Sansberro, P.A. (1,2)(1) Laboratorio de Biotecnología Aplicada y Genómica Funcional, IBONE, CONICET, Argentina. (2) Facultad de Ciencias Agrarias, UNNE, Argentina.Metallothioneins (MTs) are low molecular weight proteins, rich in cysteines that bind metal ions, thus avoiding intoxication due to their excess. It is presumed that the gene encoding MTs is driven by a promoter inducible by various types of abiotic stress. Primers and vectors were designed to evaluate the spatio-temporal expression of I. paraguariensis promoter (pMTs) and the target gene (IpMTs2), and then Lotus tenuis plants were transformed with the pMTs:GUS construction. For the design of the in silico primers, the primer 3 plus version 4.0 software was used as a base for the gDNA sequence for the promoter and cDNA for the MTs2 gene of I. paraguariensis plants. Those primers that answered the criteria established by Abdelsalam were selected, and their physical characteristics were evaluated using the program Oligo Analyzer 3.0 of Integrated DNA Technologies. To obtain the vector pMTs:GUS, the amplified sequences under study were digested with the restriction enzymes HindIII and BamHI to obtain the cohesive border required to ligate them into the pBI plasmid with the enzyme T4 DNA ligase. Next, the construction was cloned in E. coli, and the vector was introduced into Agrobacterium tumefaciens, confirming its insertion by PCR with the specific primers. L. tenuis plants were transformed with the pMTs:GUS vector; as a result of the transformation with 50 explants, 80% regeneration/selection was obtained, with 3±1 buds/explant, obtaining 50 transgenic lines. Then, the histochemical assay of the GUS gene was performed with transgenic plants subjected to various types of abiotic stresses to determine the expression of the GUS reporter gene directed by the pMTs. It was determined that the promoter is inducible and guides the expression of the gene in the aerial part of plants subjected to the following stress conditions: drought, salinity, cold and the presence of Fe, not detecting expression in the presence of Co, Cu, Mn or Zn.Metallothionein, genetic transformation, promoter, stress.
Antioxidant response mechanism in leaves of tomato plants subjected during flooding and post-flooding stressChavez César Antonio (1)Mignolli, F.(1,2); Medina, R (1,2). D.; Vidoz M.L. (1,2)(1) Instituto de Botánica del Nordeste (IBONE-CONICET). (2) Facultad de Ciencias Agrarias (FCA-UNNE).

Flooding events have increased in frequency and intensity in recent years due to climate change threatening sensitive crops such as tomato. Flooding stress hampers photosynthesis and gas exchange, as well as causes oxidative stress due to the accumulation of reactive oxygen species (ROS). Plants can scavenge ROS by synthesising and activating enzymatic antioxidants (EAs) and non-enzymatic antioxidants (NEAs). Although this response has been studied in various biological systems during flooding, little is known about the events that take place when the water recedes. In this study, we analysed the content of NEA and the EA activity in tomato plants during flooding and post-flooding stage. Four-week-old tomato plants (cv Ailsa Craig) were submerged in water up to the cotyledonary node. After six days of flooding, water was drained, and plants were kept at field capacity for six days more. Analysis of NEA (total phenolic compounds, flavonoids, anthocyanin, ascorbic acid and glutathione) and EA (superoxide dismutase SOD, catalase CAT, ascorbate peroxidase APX and glutathione reductase GR) were performed. During flooding, total phenolic compounds, flavonoids, anthocyanin, and ascorbic acid but not glutathione increased significantly. SOD and CAT only were induced and during post-flooding NEAs remained significantly higher than in controls during post-flooding as opposed to anthocyanins and glutathione. The activity of APX, GR and SOD was as low as controls while CAT remained activated. These results suggest that NEAs and CAT could be the primary mechanism to scavenge ROS both in flooding and post-flooding. The increase in ascorbic acid contents was not associated with a change in glutathione and APX activity. This suggests that ascorbic acid might not be involved as an electron donor for the dismutation of superoxide ions, and a direct antioxidant action is proposed.

flooding, post-flooding, antioxidant response
Micro RNA biogenesis and movement in plant defense pimingCambiagno, Damian AlejandroQuevedo, L.; Alanie, N.; Tenchi, A.; Lascano, H.R.Grupo de Biologia del Estrés, Unidad de Estudios Agropecuarios, INTA-CONICETver resumen adjunto.Micro RNAs, plant defenses, priming.
Postharvest physiology and nutritional quality of strawberry under salicylic acid, melatonin, and cysteine treatmentsVerónica Ruizver adjuntover adjuntover adjuntover adjunto
Water and nutritional budget of sunflower crop in a semiarid environmentDillchneider, A (1, 2)Funaro, D. (1); Gigli, A. (2); Noellemeyer, E. (2)(1) Instituto Nacional de Tecnología Agropecuaria. (2) Facultad de Agronomía, Universidad Nacional de La Pampa, Argentina.Weather and nutrients, particularly nitrogen, are the most limiting factors in agricultural production in many parts of the world, especially in semiarid zones. The aim of the study was to gain insight into the complex interactions between soil and crop management such as nitrogen fertilization rate to improve WUE and NUE simultaneously in sunflower crops of semiarid environments. The study was conducted at INTA Anguil on two soil types: a petrocalcic Paleustoll (Loam) and a typic Ustisament (Sandy). Six fertilization treatments were assigned: 1=Control, 2= 0N + 20 kg ha-1 P, 3=40 kg ha-1  N + 20 kg ha-1  P, 4=80 kg ha-1  N + 20 kg ha-1 P, 5=120 kg ha-1  N + 20 kg ha-1  P, 6= 160 kg ha-1  N + 20 kg ha-1  P. Soil characteristics were measured. Biomass, N biomass, yield grain and oil concentration were determined. Nutrition nitrogen index (NNI) was calculated. The study revealed that soils with different water holding capacities showed variations in available water during the entire crop cycle. Soil N supply influenced in N conversion efficiency (NCE) intensifying nutritional deficiency (INN<0.8). With similar soil N supply, N uptake efficiency (NUpE) was 27% higher in Loam soil than Sandy Soil. N uptake accounted for 62 and 67% of the variation in yield and WUE, respectively. In sandy soil maximum yield (3253 kg ha-1) and maximum WUE (7 kg ha-1 mm-1) were achieved with 64 kg N biomass. Loam soil exhibited a lineal relation between yield and WUE with N uptake. Maximum yield and WUE did not affect the NUE in both soils. High N supply in Loam led to lower oil content, while no significant variation was observed in Sandy soil. Loam soils had 4% more oil content than Sandy soil. Unlike other crops, sunflower crops demonstrated the potential to increase both yield and water simultaneously without compromising NUE. Nevertheless, soil type had an impact on NUpE and limited potential yield and oil content, while soil N supply influenced NCE, increasing yield and WUE.water use efficiency, soils types, nitrogen use efficiency
Improving nitrogen use in rice with gene networksMariana Obertello (1)Muschietti, J. (1, 2); Romei, F (1)(1) Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” INGEBI-CONICET, Bs. As., Argentina. (2) Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, UBA, Bs. As., Argentina.Plants exhibit remarkable plasticity, enabling them to adapt their morphology in response to environmental stimuli, crucial for survival and growth. Among the important nutrients for plant growth, nitrogen (N) stands out as a limiting factor. The indispensable role of N fertilizers in ensuring world food security together with the significant threats they pose to the ecosystem, makes the usage of N fertilizer a major challenge for sustainable agriculture. Genetic improvement of crops with high N-use efficiency (NUE) emerges as a promising solution to mitigate these challenges.
It is well-established that different plant species signal the presence of N transcriptionally. Although the genes constituting these signal transduction pathways are under intensive scrutiny, the quantitative relay of environmental signals has received less attention.
To bridge this gap, we conducted a systematic comparison of transcriptomic responses between two model species, rice and Arabidopsis. Our findings reveal a core network response, indicating a conserved mechanism of nitrogen response between these two plant species. Within this network, we identified a GARP G2-like as one of the rice core responsive transcription factors involved in mediating the amplitude of N-dose responses at both transcript and phenotypic levels. In addition, the analysis of the promoter region indicates that this transcription factor is involved in ABA and stress responses as well.
Therefore, our cross-species analysis proves to be a fruitful approach for identifying key loci of interest and sheds light on the shared aspects of transcriptional responses to N and other abiotic stress across plant species. These findings contribute to our understanding of the molecular basis underlying plant adaptation to varying N conditions, with potential implications for enhancing N use efficiency in crop plants.
Nitrogen, transcriptor factor, rice.
Hormonomics of Prunus persica (peach) leaves inoculated with Taphrina deformansNovello, M.A. (1)Petřík, I. (2); Karady, M. (2); Oklešťková, J. (2); Novák, O. (2); Valentini, G.H. (3); Strand, M. (2); Lara, M.V. (1)(1) Centro de Estudios Fotosintéticos y Bioquímicos CEFOBI. (2) Laboratory of Growth Regulators, Institute of Experimental Botany, The Czech Academy of Sciences & Faculty of Science, Palacký University, Olomouc, Czech Republic. (3) Estación Experimental San Pedro, INTA.Peach leaf curl (PLC) is a widespread disease, caused by the fungus Taphrina deformans, characterized by leaf hyperplasia and hypertrophy. PLC leads to significant decreases in peach yield, resulting in substantial economic losses. The objective of this study was to investigate the hormonal response of two peach genotypes, one susceptible (DOFI-71.043.018, DS) and another resistant (DOFI-84.364.060, DR) to the pathogen, after 12 and 96 hours post inoculation (hpi) with T. deformans. Hormone profiling in leaves was conducted by targeted metabolomics using non-selective extraction and extremely sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry. The procedure allowed the identification of 15 species of cytokinins, 7 different brassinosteroids, 7 types of auxins and derivatives, 5 different jasmonates (JA) and 5 species of abscisates. The precursor of ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC), and salicylic acid (SA) were also quantified.

Active BRs exhibited a similar response of increase in DS and DR genotypes after inoculation while active JAs decreased in both genotypes. Additionally, in DS genotype, there was a significant increase in ACC, abscisates and auxins levels at 96 hpi compared to 0 hpi. Therefore, this increase in auxins could be responsible for the later cell elongation and proliferation observed in curled and thickened diseased leaves. On the other hand, SA only increased in the DR at 96 hpi; thus, SA may play a crucial role in the defense mechanism against the fungus, which conducts to the resistance to the pathogen. Moreover, SA response pattern parallels that of isochorismate synthase previously reported by our group.

To our knowledge, this is the first hormone profiling conducted in leaves of Prunus persica. Together, data acquired provides a significant contribution to the understanding of the diverse mechanisms operating in P. persica genotypes with differential susceptibility to T. deformans.
The role of BBX proteins in shade avoidance in Solanum lycopersicum (tomato).Javier Botto (1)Mariano Mejia (1); Gabriel Ponciano (2); Gabriel Gomez-Ocampo (1); Maria Magdalena Rossi (2),(1) IFEVA (CONICET-UBA), Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, Ciudad Autónoma de Buenos Aires, C1417DSE, Argentina. (2) Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, 05508-090, São Paulo, Brasil.Shade avoidance syndrome (SAS) is a strategy of adaptive significance. In crowding stands, major transcriptional rearrangements underlie the reallocation of resources to elongate vegetative structures and redefine the plant architecture to compete for light capture. B-Box domain-containing zinc finger transcription factors (BBX) are involved in the SAS signaling of Arabidopsis thaliana, but their function in crops maintains elusive. Solanum lycopersicum L. genome encodes 31 BBX genes, and here we explored the role of SlBBX20 locus by means characterizing the behavior of Slbbx20 mutant in simulated shade and high plant density conditions. We found that the mutant genotype did not respond to simulated shade for hypocotyl and first internode length phenocopying shaded wild type plants. These results were confirmed in high density stands for plant height, first and second internodes elongation and leaf hyponasty. Our results suggest the relevance of SlBBX20 to sustain the SAS in tomato, and this knowledge can contribute to design strategies to tailor plant architecture in high-density tolerant cultivars.Solanum lycopersicum, B-Box protein, Shade avoidance syndrome (SAS), plant architecture
Characterisation of maize landraces from Argentina at the phenotypic and biochemical levelsPía Guadalupe DomínguezDudzien, Tatiana L. (1); Defacio, Raquel (2); Paniego, Norma (1); Lia, Verónica V. (1,3); Domínguez, Pía Guadalupe (1)(1) Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Hurlingham, Buenos Aires, Argentina. (2) Estación Experimental Agropecuaria Pergamino, INTA, Pergamino, Buenos Aires, Argentina. (3) Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.In Argentina, there are about 60 maize (Zea mays ssp. mays) landraces, with two main diversity centres in the Andean and Mesopotamian-Chaco plain regions. These landraces show high genetic diversity, which makes them a vital resource to increase the gene pool of modern cultivars with the aim of adapting agriculture to climate change. Although they have been largely characterised morphologically, the comparison of their biochemical and physiological-phenological characteristics has been scarcely performed. In this work, 20 accessions of maize landraces from Argentina from the “Banco Activo de Germoplasma INTA Pergamino" were analysed in a common garden under greenhouse-controlled conditions. The average number of leaves at 30 and 62 days after germination (DAG) of the 20 accessions was 8.35 (standard deviation or SD=0.98) and 15.18 (SD=2.14), respectively. Two accessions reached 100 % of male flowering at 70 DAG, eight at 77 DAG and six at 87 DAG, while the rest did not flower. Female flowering showed desynchronization with respect to male flowering, with 4 entries bearing 100 % flowering at 77 DAG, and 6 entries at 87 DAG. The average total biomass per plant was 42.24 g (SD = 30.86). In addition, various leaf biochemical variables were measured, including chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, whose averages were 1583.42 µg/ml g (SD= 878.53), 424.99 µg/ml g (SD= 231.21), 2008.41 µg/ml g (SD= 1102.43) and 370.05 µg/ml g (SD= 179.13), respectively. Leaf total sugar content mean was 37.7 µg/µl g (SD= 22.34), while that of total protein was 7.47 µg/µl g (SD= 4.3). The combination of univariate and multivariate statistical analyses showed that there is significant phenotypic and metabolic variation among the accessions, with no clear grouping patterns in relation to geographical origin or grain type. These results highlight the importance of considering the distinctiveness of individual accessions in future conservation and utilisation programs.maize landraces, phenotypic variation, metabolic variation, germplasm bank accessions
Anatomy and metabolite content of high relative humidity-induced adventitious roots in tomato (Solanum lycopersicum L.)Revollar Ochatoma, Pamela AleliMignolli, F. (1,2); Vidoz, M.L. (1,2)(1) Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste. (2) Instituto de Botánica del Nordeste UNNE-CONICET.Many environmental and endogenous factors, such as light, temperature and mineral nutrition, affect the development of adventitious roots (ARs). In addition to their economic and ecological importance, developing ARs in response to biotic and abiotic stress is crucial for plant survival, especially when the primary root system dies. High atmospheric humidity (HH) can trigger AR formation in tomato plants (Solanum lycopersicum L.), involving conspicuous anatomical and metabolic changes. For this reason, we investigated the anatomy and the content of sugars and amino acids of ARs that developed in HH compared with those formed under flooding conditions. Tomato plants of the Ailsa Craig cultivar were grown in 300 cm3 plastic pots in a growth chamber. When plants were four weeks old, they were placed individually in 1-L plastic containers. The edge of the container was sealed with a gas-permeable plastic film to maintain HH around plant stems without limiting gas exchange. Flooding was applied by submerging plant stems with water up to cotyledons. ARs formed under HH displayed higher soluble sugars (sucrose, glucose and fructose) and starch content, whereas the concentration of amino acids was similar in both types of ARs. Anatomically, ARs in HH presented a more compact cortex with expanded and isodiametric cells, while ARs from flooded plants were characterised by air spaces due to aerenchyma formation. These results indicate that ARs are differentially regulated in response to the factor that induces them and that tomato plant stems can distinguish the water potential of the external environment, resulting in the formation of either flooding or HH ARs.tomato, high relative humidity, adventitious roots.
Contrasting photosynthetic and biochemical adjustments in two aubergine (Solanum melongena L.) flooding-tolerant rootstocks subjected to waterloggingAdis, María JoséVidoz, M.L (1,2); Mignolli, F (1,2)(1) Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste. (2) Instituto de Botánica del Nordeste UNNE-CONICET.In addition to being a crop of economic importance, aubergine (Solanum melongena L.) is used as rootstock for tomato plant in areas subject to frequent flooding. This research aimed to study the response of 2 aubergine accessions to waterlogging stress. Genotypes (EG203 and TS03) were obtained and selected as flooding tolerant genotypes by Taiwan's WorldVeg genetic resource centre. Six-week-old plants were transplanted into pots containing a commercial substrate and subjected to control and waterlogging treatments. Chlorophyll fluorescence (OJIP-test) and stomatal conductance were assessed for nine days. Photosynthetic pigments, soluble sugar, starch, total flavonoids, total phenols, thiobarbituric acid reactive substances (TBARS) and total antioxidant activity (TAA) were also analysed. Stomatal conductance did not decrease in response to flooding. However, fluorescence analysis yielded a significant increase in ABS/RC and DI0/RC parameters in EG203, indicating a decrease in the number of active reaction centres and an increase in the dissipation of the energy absorbed by the antennas. In addition, the Fv/Fm index in EG203, which expresses the maximum efficiency of PSII, decreased steadily, while it remained similar to the control in TS03. Biochemical analysis showed that chlorophyll b decreased in EG203, probably due to a reduction of antenna pigments. While soluble sugars did not differ between genotypes, starch content in EG203 was significantly lower, possibly due to the reduced photosynthetic efficiency. Despite a lower content of flavonoids in flooded EG203, total phenols and antioxidant activity did not vary in response to flooding stress, and TBARS (a lipid peroxidation marker) concentration was similar in both genotypes. We suggest, therefore, that oxidative stress in leaves is not so intense as to cause membrane lipid peroxidation, but enough to cause photoinhibition of photosynthesis in EG203.Aubergine, Photosynthesis, Biochemical analysis, Flooding stress
Interactions of Phytochromes B and C fine tune the response to ambient light signalsCanelo Micaela (1)Lorenzo, Christian D (1); Cerdán, Pablo D (1,2).(1) Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires, Argentina, (2) Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina

Plants employ photoreceptors to continuously monitor and respond to changes in environmental light parameters such as intensity, duration and spectral quality. A specific group of photoreceptors, known as phytochromes, plays a significant role in regulating responses to red and far-red light. The genome of Arabidopsis thaliana encodes five distinct phytochromes (phyA to phyE), which have both specific and overlapping physiological roles. The spectrum of responses is increased by the ability of phytochromes to form heterodimers. phyB and phyC form heterodimers and phyC is nonfunctional in the absence of other phytochromes; we have shown that phyB and phyC must act together to trigger a flowering response to photoperiod. Here, we report on the roles of phyB phyC heterodimers. We used physiological and genetic approaches to uncover responses in which phyB phyC heterodimers show additional and more important roles than phyB phyB homodimers. The hypocotyl responses to light quality were highly dependent on phyB phyC heterodimers, as well as a blue light signal. Leaf shape and petiole length were also highly dependent on phyB phyC. Our data indicate that a day-light-generated blue light signal interacts with active phyB phyC heterodimers during the night period to fine tune the responses to shade.

phytochromes, light quality, Arabidopsis thaliana.
Dynamics of tocopherol concentrations accumulation in soybean exposed to brief episodes of heat and drought stress during grain fillingVeas, Rodolfo Ezequiel A.Ergo, V.V. (1); Asís, R. (2,3); Lascano, R. (1,2,4); Carrera, C. S. (1,2,5)ver documento adjuntover documento adjuntoGlycine max (L.) Merr, health-beneficial compounds, tocopherols, high temperature stress, water deficit.
Soybean growth promoting autochthonous Trichoderma spp. for biocontrolSantone, A.Campos Bermudez; V. A. (1); Smpampinato, C. P.(1)(1) Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI – CONICET). Facultad de Ciencias Bioquímicas y Farmacéuticas - UNRSoybean yield and grain quality usually decrease due to phytopathogens, such as Diaporthe caulivora which cause stem canker. The use of growth-promoting microorganisms as biological control agents present a sustainable alternative to agrochemicals. Trichoderma, a genus of filamentous fungi inhabiting the rhizosphere and beneficially interacting with plant roots, shows promise in this regard. We identified and selected autochthonous strains of Trichoderma with the ability to promote soybean growth and control D. caulivora. Three strains of Trichoderma (T4, T10 and T12) were isolated from the local soil biota. The ITS, Rpb2, and Tef1 genes were amplified and sequenced to identify the strains as members of the Trichoderma harzianum complex. First, in vitro tests were carried out. We observed that all the strains inhibited the growth of D. caulivora. T10 and T12 showed carboxymethyl cellulase activity producing 0.66 and 1.64 nmol/mL of glucose, respectively. T4 and T10 with the addition of Trp produced 16 and 10 μg/mL of indoleacetic acid, respectively. Also, all the strains were able to solubilize phosphate. Then, in vivo tests were conducted on hydroponically and soil-grown soybean. Stem cuttings from two-week-old plants were exposed to 1:500 V/V diluted cell-free liquid from T4, T10, T12 and T. harzianum cultures, with and without TRP. Moreover, soybean seeds were inoculated with supernatants from each strain, with and without conidia. After 21 days of sowing, plants were infected with D. caulivora. Results indicate that the T10 strain showed the most promising results. It promoted robust root development and displayed the lowest water consumption in hydroponic conditions. In the soil trial, it exhibited the lowest number of dead plants after infection, thus concluding that this strain has a significant potential to promote soybean growth and control the pathogen. Further studies are being conducted to determine secondary metabolites released by the T10 strain.
Physiological characterization of drought tolerance in peanutMonteoliva Mariela InesGuzzo MC1, Posada GA2, Suarez P1, Luna FD1, Schenfeld E1, Espinosa Herlein MA1, Bustamante OM1, Ruiz OA3, Monteoliva MI11-Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV-UDEA), CIAP, INTA-CONICET, Córdoba, Arg. 2-FCQ, UNC, 3- INTECH (UNSAM-CONICET)Drought is one of the most limiting environmental factors reducing yields in agriculture. Peanut is a crop usually carried out raid-fed only which makes it susceptible to seasonal droughts. Drought tolerance could manifest in several physiological responses, such as higher relative water content (RWC), higher chlorophylls, proline, or FRAP, or lower MDA (oxidative damage). To improve productivity under these conditions, it is relevant to identify and characterize drought-tolerant responses in peanut. Our project aimed to characterize drought tolerance in peanut in vegetative and reproductive stages, under controlled drought. We evaluated peanut lines from Criadero El Carmen (Gral. Cabrera, Cordoba, Argentina) and then we characterized them in deep on of them. We previously found variability in stress responses, with genotypes that keep higher RWC than 70%, and exhibited biochemical changes. Here we will discuss novel results in sugar content (by HPLC) and photosynthesis-related parameters. We found differences in leaf temperature, internal CO2 concentration in the mesophyll, and stomatal conductance.

Funds: INTA-PE-2019-I516, INTA-PD-2023-I084, INTA-PE-2023-I071, PICT 2018-01326.
Arachis hypogaea, germplasm, water deficit, legumes, phenotyping
Winners and losers: Climate change effects on forests and cropsDanielle WayDanielle Way(1) Division of Plant Science, Research School of Biology, The Australian National University. 134 Linnaeus Way, Acton, ACT, Australia 2601. (2) Department of Biology, University of Western Ontario. 1151 Richmond Street, London, ON, Canada. N6A 3K7Rising atmospheric CO2 concentrations could reach >1000 ppm by 2100, increasing global temperatures 3-4 °C. Both elevated CO2 and warming affect photosynthesis, plant growth, survival, and crop yield and quality. Climate change-induced shifts in photosynthesis and plant growth also affect the global carbon cycle, mitigating or accelerating further climate change. Understanding how plants acclimate to future climate conditions is therefore critical for accurately predicting the trajectory of future climate change, as well as for estimating plant productivity in a warmer, high COworld. I’ll discuss how elevated temperatures, high CO2 concentrations and vapor pressure deficit impact forest and crop performance using results from my lab and meta-analyses.global warming, photosynthesis, plant biomass
The mitochondrial enzyme ProDH controls the cytosolic redox homeostasis in ArabidopsisAna Paula CislaghiÁlvarez M.E.Centro de Investigaciones en Química Biológica de Córdoba, CONICET, Córdoba, Argentina; Departamento de Química Biológica, FCQ, UNC, Córdoba, Argentinaver resumen adjunto.ProDH, redox, oxidative stress, phytopathology.
Novel roles for Mediator complex in Arabidopsis thaliana flowering timeSantiago N. FreytesJaskolowski, A (1); Viñas, E (1); Iñigo, S (1); Yanovsky, M (1); Cerdan P. (1).(1) Fundación Instituto Leloir, IIBBA-CONICETMediator is a large protein complex that is conserved in eukaryotes and has an essential role in RNA polymerase II (RNA pol II)-mediated transcription. It consists of 29 subunits in Arabidopsis thaliana and its role in plant development, such as flowering regulation, and defense, has emerged as an important contribution. We previously described the role of PFT1 (PHYTOCHROME AND FLOWERING TIME 1)/MED25, a nuclear protein that acts in a phyB pathway and induces flowering in response to suboptimal light conditions. We searched new mutants of Mediator complex that affect flowering. Among them we found PFT2. We generated mutants using CRISPR-Cas9. The lack of this gene causes a delay in flowering, compared to the control. We verified that the response to photoperiod, temperature and vernalization is conserved. However, the autonomous pathway seems to be involved, as pft2 mutants exhibit high levels of the flowering repressor FLOWERING LOCUS C (FLC), and the double mutants flc pft2 suppress the late flowering phenotype, but it is independent of SHORT VEGETATIVE PHASE (SVP). Furthermore, the response to gibberellins is more severe in pft2 mutants, especially under short day photoperiodic conditions. Interestingly, this stronger response to gibberellins accelerates flowering but significantly increases the number of cauline leaves in pft2 compared to wild type. Thus, PFT2 may be involved in the development of A. thaliana by promoting flowering, acting in the autonomous and gibberellin pathways.Mediator Complex, flowering, Arabidopsis, development
Unveiling the Role of NADP-ME and NAD-ME in C4 Photosynthesis of Setaria and PanicumPaula CalaceMariel Gerrard Wheeler, Mariana SaigoCentro de estudios fotosinteticos y bioquimicos, CEFOBI, Rosario, Argentina.Understanding the functioning of C4 photosynthesis is of vital importance due to the impact of climate change and the need to improve the efficiency of carbon fixation in plants. In the context of this work, closely related species, Setaria viridis and Panicum virgatum, which belong to different subtypes of C4 photosynthesis, named NADP-ME and NAD-ME, were investigated.

In order to better understand the role of NADP-ME and NAD-ME isoforms in C4 photosynthesis, an integrative analysis was performed combining kinetic and regulatory studies with proteomics in both subtypes. A comparison of the proteomes of mesophyll and bundle sheath cells in both Setaria and Panicum was carried out, and these data were related to transcriptomic information from these species and other widely studied nearby species, such as maize. In both S. viridis and P. virgatum, evidence was found for the combined involvement of both decarboxylase enzymes in the process of C4 photosynthesis. This finding is of great relevance for understanding and optimising metabolism, and raises the need to further investigate the conditions under which these pathways coexist in both plants.

In summary, this work highlights the importance of studying C4 photosynthesis in the context of climate change, focusing on the relationship between S. viridis and P. virgatum species, which, although closely related, belong to different subtypes of C4 photosynthesis (NADP-ME and NAD-ME). The findings obtained provide valuable information on C4 metabolism and open new research perspectives in this field.
Arabidopsis interaction with beneficial pseudomonas strains that confer tolerance to drought stress and promote root developmentLlamedo, Ignacio (1)Chaín, J.M. (1); Gudesblat, G. (2), Amodeo, G. (1), Baroli, I. (1)(1) Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, UBA-CONICET) & Departamento de Biodiversidad y Biología Experimental (DBBE, FCEyN-UBA). (2) Instituto de Biociencias, Biotecnología y Biología Translacional (IB3) & Departamento de Fisiología, Biología Molecular y Celular “Dr. Héctor Maldonado” (DFBMC, FCEyN-UBA).Within the global climate context, where plants face diverse environmental stresses, particularly water deficit, the application of growth-promoting bacteria (PGPB) stands out as a sustainable strategy to improve stress tolerance. PGPB can be found in the soil microbiota or in the phyllosphere, where they can stimulate the host plant growth and development, aid in nutrient uptake or enhance pathogen resistance. Some PGPB release phytohormone analogues or modify hormone signaling pathways in the host plant. Our group has found that two Pseudomonas strains isolated from agro-environments in Buenos Aires province, called M25 (originally described in [1]) and N33[2], promote drought tolerance in eucalyptus seedlings by enhancing water management through changes in stomatal conductance and cell wall elasticity[2]. We also showed that the strains exert their action from the rhizosphere, without colonizing plant tissues. These results prompted us to switch to arabidopsis as an amenable system where to investigate the mechanism of action of the bacteria at the root level. When plants were grown on agar plates, inoculation with M25 or N33 promoted changes in primary root length and lateral root number, each strain eliciting phenotypes different from each other and from control seedlings. Both strains produced a remarkable increase in the number and length of root hairs on primary roots. We used an arabidopsis line carrying the auxin-inducible DR5 promoter fused to GFP to analyze the participation of auxins in the bacteria-induced changes in root architecture. Compared with the control, we did not detect significant differences in the number of green fluorescent nuclei in inoculated root apices. These results indicate that arabidopsis is a suitable model to further study the mechanisms by which N33 and M25 bring about changes in root architecture and tolerance to drought.

[1] Castagno et al. (2011) J Appl Microbiol 110: 1151–1165
[2] Chaín et al. (2020) Sci Rep 10: 1–17
beneficial bacteria, root development, drought, water deficit stress, hormone
Effector repertoire of a dominant Phytophthora infestans isolate in Argentina and its relevance for late blight resistance deployment in potato.Juarez, M.E.(1)Lucca, M.F.(2); Azcue, J.(1);; Bravo Almonacid, F.F.(1,4); Cano Mogrovejo, L.M. (3); Segretin, M.E.(1,5)(1) INGEBI - CONICET. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Argentina. (2) Instituto Nacional de Tecnología Agropecuaria EEA Balcarce, INTA, Argentina. (3) University of Florida, United States. (4) Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Argentina. (5) Departamento de Fisiología, Biología Molecular y Celular, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.Phytophthora infestans, the causal agent of potato late blight disease (LB), is a major threat to
potato crops and global food security. Management of LB in the field depends on repeated
application of chemicals, many of which will be withdrawn from the market in the near future.
The most sustainable strategy to manage late blight is to breed disease resistance into potato
following a knowledge-based approach. Plant pathogens can colonize their hosts by secreting a
plethora of effectors to facilitate infection. Certain plant genotypes can specifically recognize
these effectors and mount active defenses to limit pathogen growth, a mechanism known as
effector-triggered immunity (ETI). ETI requires the recognition of the target effector protein by
host´s immune receptors, particularly Resistance (R) proteins. Potato breeders have
incorporated R genes from wild Solanum species to commercial varieties with promising
results for LB control. Understanding effector repertoire of local P. infestans isolates will be
crucial to deploy effective resistance mediated by R proteins. In Argentina, potato production
is primarily intended for fresh consumption, with up to 80% of cultivated area dedicated to
Spunta variety. Despite Spunta express R1 protein (recognizes AVR1 effector protein), it is
highly susceptible to LB. The objective of this work was to analyze P. infestans isolates
obtained from different potato producing areas of Argentina by SSR markers, and to
characterize a dominant isolate at genomic and transcriptomic levels by Illumina high-
throughput sequencing. We performed RNAseq to determine pathogen´s gene expression
profile during infection of Spunta leaves. We focused on expression levels of a set of effectors
targeted by described R proteins. These genes were further analyzed characterizing their allelic
variants, copy number variation and gene loss assessment. The information generated in this
work will be critical to deploy durable resistance in potato.
Phytophthora infestans, effector, resistance
Comparative transcriptomic, proteomic and amino acid content analyses of quinoa (Chenopodium quinoa) seed accessions from Northwest ArgentinaBarberini María LauraBarberini María Laura (†1), Lee Yun Sun (†2), Guerrero Leandro Demian (†1), Obertello Mariana (1), Mazzella María Agustina (1), Bertero Daniel Héctor (3), Grotewold Erich (2) and Muschietti Jorge Prometeo (1,4)(1) Instituto de Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” (INGEBI-CONICET), Buenos Aires, Argentina. (2) Department of Biochemistry and Molecular Biology, Michigan State University, USA. (3) Cátedra de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina. (4) Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.Quinoa (Chenopodium quinoa), a pseudocereal native to the Andean regions, is mainly characterized by the quality and nutritional value of its proteins due to an excellent balance of essential amino acids. To identify nutritional attributes and classify the different germplasm accessions, we performed comparative proteomic and transcriptomic studies among four landraces of quinoa from different genetic groups in the Northwest Argentina (NWA) region and QQ74, the sequenced Chilean coastal variety. We analyzed the quinoa seed’s transcriptome by aligning the results of RNA-seq to the second version of the genome. After filtering and normalizing 29,355 transcripts, we observed that the QQ74 variety is the most distinct compared to the NWA landraces. Subsequently, we performed a differential analysis of the transcripts in the 10 pairwise comparisons and identified a total of 3,014 DEGs. To further explore the role of these DEGs, a Gene Ontology enrichment analysis showed significant differences in various GO terms and comparisons. However, one of the most interesting findings is that the landrace representing the NWA geographical transition area shows enrichment in the terms related to oxidative phosphorylation and heat response. Moreover, using 2D-gel electrophoresis and mass spectrometry, we demonstrate that the storage proteins (11S globulin, 13S globulin and vicilin-like antimicrobial peptides), are the most abundant proteins found in our quinoa seeds. We also observed that some of these proteins are differentially expressed among these landraces. Additionally, we analyzed the total amino acid content in the seeds of the five varieties. Despite finding statistically significant differences in Lysine content between the landrace from Dry Highlands and the one corresponding to the transition area, and in Leucine content between the representative variety of Dry Valleys and QQ74, there are no major differences in the amino acid content among all the varieties. Quinoa, proteome, RNA seq, seed storage proteins, amino acids content, Northwest Argentina
Influence of GLRaV-3 infection on grapevine growth, phenology, and ripening: insights from Malbec and Torrontés Riojano varietiesBarrios Bogado, Pablo EzequielHugalde, I. P. (1); Delgui, L. R. (2); Catania, A. A. (1); Gómez Talquenca, S. G. (1)(1) Laboratorio de Fitovirología, INTA, Argentina. (2) Instituto de Histología y Embriología de Mendoza, ArgentinaWe studied the impact of Grapevine Leafroll-associated Virus 3 (GLRaV-3) on phenological and physiological traits of Malbec and Torrontes Riojano (TR) grapevines. Samples were obtained from the INTA-EEA Mendoza vineyards, where two Malbec clones, selected according to average yield, and one TR clone were studied. We have assessed the vine development, productivity, and sugar accumulation throughout the growing season, from pre-budburst to veraison and during grape ripening. Significant variations were observed between infected and healthy Malbec vines in early phenological stages, specifically between pre-budburst and budburst, with infected plants exhibiting a noticeable phenological delay. At post-veraison, significant delays in sugar accumulation (°Bx) were evident in infected Malbec clones. Additionally, infected Malbec clone 12 and clone 14 showed a prolonged cycle from 17°Bx to 24°Bx, and from budburst to harvest, respectively, when compared to healthy plants, highlighting the influence of GLRaV-3 on ripening duration. Notably, similar differences were also observed in TR, with a longer period from 17°Bx to 24°Bx and variations from stage 12 to full maturity in infected plants. These findings underscore the significant impact of GLRaV-3 on grapevine development and ripening in both Malbec and TR varieties. Yield and grape composition parameters were evaluated. Infected Malbec plants exhibited distinct differences regarding pruning weight, flowers per cluster vs. pruning weight, and clusters vs. pruning weight. These effects seem linked to plant ability to store nutrients from one season to the next, with flowering standing as a critical developmental stage. This study emphasizes the diverse GLRaV-3 responses of Malbec and TR grapevines, underlying the importance of vineyard management strategies, especially when dealing with viral infections, and the significance of selecting healthy clones and genotypic favourable traits concerning viticultural productivity.Grapevine Leafroll-assciated Virus 3 (GLRaV-3), phytovirology, Malbec, Torrontés Riojano, plant phenology, grapevine development, sugar accumulation,
Mitotic and Endoreplication Cell Cycles in Plant Organ GrowthProf. Dr. Ramiro Rodriguez-Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR) y Centro de Estudios Interdisciplinarios (UNR). Rosario, Argentina.Within plant meristems, the mitotic cell cycle (MCC) produces new cells that subsequently engage in cell expansion and differentiation programs. The latter is frequently associated with endoreplication (ER), an alternative cell cycle that replicates the DNA without nuclear division, causing an increase in somatic ploidy.

MCC regulators have oscillating activities regulated by transcriptional and posttranscriptional mechanisms. For example, the E2F and MYB3R transcription factors (TF) control gene expression during the G1/S and G2/M transitions. Genomic studies indicated that only a subset of the genes with expression enriched at the G1/S or G2/M transitions are directly regulated by the E2F or MYB3R TFs, suggesting that other regulators remain to be identified.

To identify these genes we first analyzed the transcriptome of cells in G2/M and found hundreds of genes whose expression is reduced or enriched in G2/M cells. This dataset enabled us to identify new potential regulators, including TFs, proteins involved in redox and calcium metabolism, motor proteins, etc.

Here, we focus on SCARECROW-LIKE 28 (SCL28), a GRAS transcription factor, whose mRNA accumulates to the highest levels in G2/M and is regulated by MYB3R transcription factors. Functional analysis indicates that SCL28 promotes progression through G2/M and modulates the selection of cell division planes.

Surprisingly, gene expression studies indicated that SCL28 regulates SIAMESE-RELATED genes, encoding CDK inhibitors with a role in promoting mitotic cell cycle exit and endoreplication. Consistent with this, mutants in SCL28 displayed reduced endoreplication. We also found evidence indicating that SCL28 regulates genes related to the biogenesis, assembly and remodeling of the cytoskeleton and cell wall.

Altogether, our results suggest that SCL28 controls plant organ growth by modulating not only cell proliferation, but also endoreplication, cell expansion and differentiation.
mitotic cell cycle, development, endoreplication, cell expansion
Regulatory networks of TCP transcription factors during Arabidopsis seedling developmentIvana L. ViolaAlem, A.L.; Jure R.M.; Gonzalez D.H.Instituto de Agrobiotecnología del Litoral, CONICET-UNL, ArgentinaAfter germination, exposure to light promotes the opening and expansion of the cotyledons and the development of the photosynthetic apparatus in a process called de-etiolation. This process is crucial for seedling establishment and photoautotrophic growth. However, transition to light is a challenge for dark-germinated seedlings, since light can be harmful to the plant during the de-etiolation process. When the plant grows in dark conditions, illumination can produce photooxidative damage, which affects the accumulation of chlorophyll, photosynthesis and, eventually, the growth or survival of the plant. To avoid this, a number of key regulatory factors are required for the control of chlorophyll biosynthesis during this transition.
TEOSINTE BRANCHED 1, CYCLOIDEA, and PROLIFERATING CELL FACTORS (TCP) transcription factors constitute a plant-specific protein family that participates in the regulation of numerous processes of growth and development during the life cycle of plants, acting through the recruitment of other factors and the modulation of different hormonal pathways. In our laboratory, we found that different TCP proteins participate in processes associated with de-etiolation, like cotyledon opening and expansion, as well as the induction of genes encoding components of the photosynthetic apparatus, physically interacting with the transcription factor GLK1 and integrating into the transcriptional network associated with this transcription factor. TCP proteins also affect the accumulation of chlorophyll precursors in etiolated seedlings supporting a role of these proteins in the protection from photooxidative damage after light exposure. The molecular mechanisms related to the action of TCP transcription factors in these processes will be discussed.
molecular biology, Arabidopsis thaliana, transcription factors, TCP, GLK, photomorphogenesis
Plastids targeted BNT1 immune receptor implicated in the organelle-associated defense responses in Arabidopsis.Peppino Margutti M.YHerrera-Vasquez A (2), Cislaghi A.P. (1), Palomeque J.R. (1), Bellino F. (1), Alvarez M.E. (1), Blanco-Herrera F. (2), Cecchini N.M. (1)(1) CIQUIBIC-CONICET, Departmento de Química Biológica-Ranwel Caputto, FCQ-UNC, ARGENTINA; (2) Centro de Biotecnología Vegetal, Universidad Andres Bello, Santiago, CHILENucleotide-binding leucine-rich repeat receptors (NLRs) play a critical role in the plant immune system, conferring resistance against many diseases. While the functional diversity of NLRs within different cellular compartments has been extensively studied, their role in plastids, essential organelles for an effective defense against pathogens, has remained unexplored. In this study, we present in silico evidence revealing the presence of an N-terminal signal responsible for targeting an Arabidopsis NLR from the TNL family to the plastid envelope. We studied the subcellular localization of BNT1, confirming their presence in the plastid envelope. Moreover, expression analysis showed that the relative abundance of BNT1 is influenced by bacterial infection, with specific patterns of expression observed in epidermal tissue, which is proposed to play a vital role in the immunity against these invaders. The functional significance of the BNT1 was further studied by evaluating their impact on plant resistance against Pseudomonas spp. Strikingly, mutant plants deficient in this NLR exhibited altered resistance to the bacteria. To gain insights into the underlying molecular mechanisms, we assessed chloroplast redox changes in response to bacterial infections using the redox-sensitive green fluorescent protein (roGFP) ratiometric system. The results show that the NLR-mediated responses are linked to chloroplast redox regulation. Our study shows for the first time an NLR located in chloroplasts and presents evidence for the involvement of NLRs in plastid-mediated immunity, expanding our understanding of the plant immune system's complex regulation.

R proteins, Pseudomona, immune system,
Heat priming in seeds induces antioxidant defense in maize seedlingLiliana B. PenaEggel, M.L. (1), Pérez Chaca, M.V. (1), Pena, L.B. (2,3)(1) Universidad Nacional de San Luis, Facultad de Química, Bioquímica y Farmacia. (2) Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica. (3) CONICET - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológica (IQUIFIB)Most of the varieties of agricultural plants use seeds to reproduce, however, unfavorable environmental conditions can modify their germination capacity. Different priming techniques: osmo, hydro, chemical, hormonal and nutrient techniques have been used to improve seed germination and crop yield. Stress is considered as a significant deviation from optimal living conditions. Oxidative stress is produced by the imbalance between the generation of reactive oxygen species (ROS) and antioxidant defenses, which can lead to cellular dysfunction when cells are unable to efficiently regulate ROS levels or adequately remove or replace damaged macromolecules. The objective was to evaluate the oxidative metabolism, determining ROS effect on oxidative damage and antioxidant defenses, in seedlings roots in the post-germination stage of seeds with and without pre-treatments. Maize seeds (Zea mays L.) were subjected to pre-treatment with 40 or 50 °C for 3 and 7 d. Seeds with and without heat-priming were superficially disinfected and germinated on cotton and paper towel wetting at 28 °C for 96 h. The determinations were made using the apical 2 cm of the roots. Catalase (CAT), guaiacol (GPX), ascorbate peroxidases (APX), and superoxide dismutase (SOD) activities were determined. Macromolecules damage was measured as thiobarbituric acid reactive substances (TBARS) and carbonyl group content (COOH). Root growth was induced by heat-priming at 40 °C. Heat pre-treatments modified redox balance modified GPX, APX, CAT, and SOD activities significantly. On the other hand, pre-treatments at 50 °C showed an increase in TBARS and COOH, and reduced total -SH groups. Thus, pre-treatment at 40 °C for 3 d didn’t modify ascorbate and proline contents. According to these results, we propose that seeds primed at 40 °C have induced antioxidant enzymatic defense that would limit oxidative damage to macromolecules in maize seedlings.Zea mays, oxidative stress, antioxidant defenses, oxidative damage
BBX21 integrates brassinosteroid biosynthesis and signalling in the inhibition of hypocotyl growth under shadeGabriel Gómez-Ocampo (1)Crocco, C.D. (1); Cascales J. (1); Oklestkova J. (2); Tarkowská D. (2); Strnad M. (2); Mora-Garcia S. (3); Pruneda-Paz J.L. (4); Blazquez M.A. (5) Botto J.F. (1)(1) IFEVA (CONICET-UBA), Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, Ciudad Autónoma de Buenos Aires, C1417DSE, Argentina. (2) Laboratory of Growth Regulators, Palacký University & Institute of Experimental Botany, The Czech Academy of Sciences, Šlechtitelů 27, CZ-78371 Olomouc, Czech Republic. (3) Fundación Instituto Leloir, IIBBA- CONICET, Avenida Patricias Argentinas 435, Ciudad Autónoma de Buenos Aires, C1405BWE, Argentina. (4) Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA. (5) Instituto de Biología Molecular y Celular de Plantas, CSIC-Universitat Politècnica de València, C/Ingeniero Fausto Elio s/n, Valencia, 46022, Spain.B-Box-containing zinc finger transcription factors (BBX) are involved in light-mediated
growth, affecting processes such as hypocotyl elongation in Arabidopsis thaliana. However, the
molecular and hormonal framework that regulates plant growth through BBX proteins is
incomplete. Here, we demonstrate that BBX21 inhibits the hypocotyl elongation through the
brassinosteroid (BR) pathway. BBX21 reduces the sensitivity to 24-epiBL, a synthetic active BR,
principally at very-low concentrations in simulated shade. The biosynthesis profile of BRs showed
that two active BR -brassinolide (BL) and 28-homobrassinolide (28-homoBL) can be repressed by
BBX21 under white light (WL) or simulated shade. Furthermore, BBX21 represses the expression of
and BR6OX2 (CYP85A2) genes involved in the BR biosynthesis in WL while promotes DWF4
expression in WL + FR (far-red), a treatment that simulates shade. Furthermore, we found that
BBX21 interacts genetically with BZR1, and their effects are not additive in the hypocotyl growth
response. We propose that BBX21 integrates the BR homeostasis and shade-light signalling
allowing the fine-tuning of plant elongation responses.
B-box protein, brassinosteroids, shade, hypocotyl growth
Identification of candidate genes controlling vernalization requirement and flowering onset in carrotAndrés Morales (1, 2)Wohlfeiler, J. (1, 3); Cavagnaro, P. F. (3,4,5); Galmarini, C. R. (1,3,5)(1) EEA La Consulta, INTA, Argentina. (2) Laboratorio de Biología Molecular, Instituto de Biología Agrícola Mendoza - CONICET, Facultad de Ciencias Agrarias - Universidad Nacional de Cuyo, Argentina. (3) CCT Mendoza, CONICET, Argentina. (4) EEA Mendoza, INTA, Argentina. (5) Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Argentina.Carrot is a major horticultural crop, highly valued as a staple rich in bioactive compounds. Low temperatures play a key role in carrot growth cycle, and varieties are classified as annual or biennial based on their vernalization requirement (VR). A simply-inherited dominant locus localized in chromosome 2, termed ‘Vrn1’, was found to be responsible for VR in segregant populations derived from the cross between Criolla INTA, an Argentine open-pollinated cultivar, and #5, a biennial line from the United States. In order to elucidate the mechanisms underlying the transition of the apical meristem, seeds of both of these genotypes were sown in pots in a growth chamber at 25 ˚C and long-day photoperiod. When the plants had 8–12 leaves, they were transferred to a vernalization chamber (5 °C and short-day photoperiod) for 80 days and then transferred back to the growth chamber. Control individuals were not exposed to cold treatment. Apical meristem tissue from both genotypes was collected at the following time-points or physiological conditions: i) pre-vernalization; ii) after 40 days of cold; iii) after 80 days of cold; iv) starting to bolt; and v) non-vernalized control. Total RNA was extracted and samples were sent to the University of Wisconsin-Madison Biotechnology Center for NGS library preparation and sequencing. Upon bioinformatic analyses using the reference carrot genome, we identified 40,874 new transcripts, including 5,625 protein-coding and 35,249 non-coding (nc) transcripts: 161 structural RNAs, 33,875 long intergenic ncRNAs (lincRNAs) and 1,213 long non-coding natural antisense RNAs, and found up to 7,372 differentially expressed genes (DEGs) between pairwise comparisons. In the vicinity of Vrn1 we found five new lncRNAs and one new protein-coding gene, and up to 10 DEGs, which are candidate genes for Vrn1. Based on these results, we plan to knock down genes via gene editing or overexpress them by transformation in both genetic backgrounds.carrot, flowering, vernalization, transcriptomics, RNAseq
Pleiotropic effects associated with the expression of a recombinant fibroblast growth factor in transplastomic plantsMüller, Carolina (1)Abraham, M. (2); Guaglianone, M. (1); Bravo-Almonacid F.F. (1,3).; Blanco, N.E (2).; Segretin, ME (1,4)(1) INGEBI-CONICET, CABA, Argentina (C1428ADN); (2) CEFOBI-CONICET-UNR, Rosario, Argentina (2000); (3) Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina (B1876BXD); (4) Departamento de Fisiología, Biología Molecular y Celular, FCEyN, Universidad de Buenos Aires, CABA Argentina (1428)Transformation of the plastid genome is a widely used method for the generation of transgenic plants, with the potential to accumulate high levels of recombinant proteins. However, foreign transgenes may cause unintended pleiotropic effects affecting plant development and physiology. The mechanisms underlying these effects are dependent on the heterologous protein and remain to be elucidated. In this study, we examined the phenotypes of transplastomic tobacco plants that express a recombinant human fibroblast growth factor (hrFGFb), a protein used for the maintenance of embryonic stem cells in vitro. The transplastomic lines (UTR-FGF) exhibited slower growth rate and delayed flowering compared to non-transformed tobacco plants (NT). In addition, UTR-FGF lines showed a chlorotic phenotype which correlated with a reduction in chlorophyll fluorescence levels (SPAD). To study whether photosynthesis is affected in UTR-FGF lines, we analyzed different chlorophyll fluorescence parameters using the pulse-amplitude modulated (PAM) technique. Analysis on dark-adapted plants revealed that the maximum quantum yield of PSII (FV/FM) was almost two-times lower in transplastomic lines compared to NT, indicating an important reduction in their photosynthetic capacity. We measured photosynthetic parameters in light-adapted leaves and obtained a significant reduction of the PSII efficiency (φPSII) and an increased NPQ (non-photochemical quenching) rate in UTR-FGF lines compared to NT. These results suggest that UTR-FGF lines have an impaired capacity to conduct photochemical reactions and likely to generate ATP and reducing equivalents by photosynthesis. The high fraction of quenching based on heat dissipation might be indicating profound perturbances in antennae complexes in the transplastomic lines. Taken together, these results demonstrate that the transformation of the plastome with hrFGFb transgene has pleiotropic effects, causing both developmental and physiological impairments.transplastomic plants, pleiotropic effects, photosynthesis
Aboveground biomass allocation in rapeseed in response to both the increase and reduction of the source-sink ratio during grain fillingConsuelo Rauque (1,2)Verdejo, J. (1,2); García, S. (1,2); Gutiérrez, A. (1,2); Calderini, D. (1)(1) Institute of Plant Production and Protection, Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile. (2) Graduate School, Faculty of Agricultural Science, Universidad Austral de Chile, Campus Isla Teja, Valdivia, ChileThe source-sink (S-S) ratio is a key trait in rapeseed (Brassica napus L.) after flowering due to its indeterminate growth habit. Flowers and siliques develop simultaneously competing for assimilates, directly affecting aboveground biomass allocation. This study attempts to understand the rapeseed biomass partitioning by increasing and reducing the S-Sratio during grain filling.

The spring hybrid Click CL (NPZ-Lembke) was sown on September 3 (2022) at field conditions in Valdivia, Chile (39°47´S, 73°14´W). Treatments consisted of a control without manipulation and two source-sink ratio modifications (50% increase and 50% reduction) imposed from the end of the lag phase to harvest. The S-Sratio increase was performed using reflective panels, while the S-Sratio reduction by shading the crop with black nets.

The S-Sratio increase improved grain yield (P=0.006) by 58% and above ground biomass (P<0.001) by 52%, while no effect (P>0.050) was found on these traits under the S-Sratio reduction treatment. Grain yield improvement was explained by the increment of 57% in grain number (P=0.004), due to a higher (P=0.001) number of siliques per m2 of 69% and more (P=0.015) branches per plant (23%). The S-Sratio increase started to improve the number of siliques per branch by 37% at the fourth (P=0.004) branch, while the increase reached 108% at the sixth branch (P<0.001). No effect has been found in the first three branches. Additionally, grain weight did not show significant differences (P>0.05) across the treatments.

Biomass allocation due to S-Sratio increase was similar to the control plot (P>0.05), while the S-Sratio reduction improved the biomass allocation of siliques and branches by 9% (P<0.001) and 73% (P=0.002), respectively. Therefore, the source-sink increase allowed a proportionally increment in the biomass allocation, due to a simultaneous increase in different organs, while the source-sink reduction gave priority to the branches over other organs.
biomass partitioning; branches; siliques; organs; indeterminate growth
Combined effects of cytokinins and brassinosteroids applied at flowering on grain yield and components of rapeseedAriel Gutiérrez Oyarzún(1),(2)José Verdejo(1),(2); Consuelo Rauque(1),(2), Sebastián García(1),(2), Daniel F. Calderini(1)(1) Institute of Plant Production and Protection, Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile (2) Graduate School, Faculty of Agricultural Science, Universidad Austral de Chile, Campus Isla Teja, Valdivia, ChileIt has been shown that the combined use of cytokinins (CK) and brassinosteroids (BR) applied during flowering increases grain number in Arabidopsis thaliana L. due to a synergistic effect between both phytohormones. These results could be emulated in a specie of the same Brassicaceae family. The objective of this study was to evaluate this effect on grain yield, its components and quality traits (oil and protein concentration) of rapeseed (Brassica napus L).
The spring hybrid Click CL (NPZ-Lembke) was sown on September 3 (2022) under field conditions in Valdivia, Chile (39°47'S, 73°14'W). The experiment consisted of a control, and three hormonal treatments; CK only, BR only and the combined application of CK and BR. Phytohormones were applied 10 days after start of flowering. The hormonal treatments were carried out using the commercial products Cytoplant-400 (400 ppm CK) and Brassinost-1 (20 ppm BR) at doses of 1 L/ha and 2 L/ha, respectively. Statistical differences were tested by ANOVA.
Grain weight was increased under the BR treatment by 11.7%, followed by 9.8% when CK was applied and by 6.7% in the combined treatment (P=0.009).These increments have not statistical impact on grain yield increase (P>0.050) causing a tendency to increase (16% for BR and 4% for the combined treatment), which was not significant due to a no existent trade-off between grain weight and grain number. Grain oil and protein concentration were not affected (P>0.050) by the hormonal treatments.
These results do not agree with previous reports in A. thaliana. Thus, the likely trade-off between grain weight and number found in rapeseed seems to be the cause of these contrasting results. The grain number and weight responses would be dependent on the type of brassica specie to which the treatment is applied.Additionally, grain weight in the combined treatment of CK and BR was lower compared to the other treatments, which suggests some negative interaction between both hormones in rapeseed.
Agronomy, phytohormones, plant physiology, rapeseed
Sensibility of seed yield and quality traits of rapeseed to increased temperature and reduced source-sink ratio in different phases of grain fillingJosé Francisco Verdejo (1, 2)Castro, C (1), Bustos-Korts, D. (1), Calderini, D. (1)(1) Institute of Plant Production and Protection, Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile. (2) Graduate School, Faculty of Agricultural Science, Universidad Austral de Chile, Campus Isla Teja, Valdivia, ChileIn the last years, climate change has increased mean temperature and reduced solar radiation in southern Chile. However, little is known about the sensitivity of grain yield, its components and quality traits to heat stress (HS) and source-sink (S-S) reduction at flowering and during grain filling. The objective of this study was to evaluate the key physiological mechanisms of rapeseed yield and oil concentration under both HS and S-S reduction at different phases of grain filling.

Rapeseed spring hybrids Lumen and Solar CL (NPZ-Lembke) were sown in four experiments carried out at field conditions in Valdivia, Chile (39°47´S, 73°14´W). HS was evaluated in Exp. 3 and 4, sowing the experiments in years 2019 and 2020, respectively, while S-S reduction was evaluated in Exps. 1 and 2 in 2018 under two sowing dates. Across experiments, three abiotic treatments were carried out: (1) a control without manipulation, (2) HS or S-S reduction from the 0 to 15 days after flowering (DAF) and (3) from 15 to 30 DAF. The HS was induced using portable greenhouses to increase 5°C over the ambient, while S-S reduction was achieved by shading with black nets (75% solar radiation interception).

HS and S-S reduction treatments affected (p<0.05) grain yield, grain number and weight being Lumen less affected than Solar CL. The impact on grain yield and components was higher during 0-15 DAF than during 15-30 DAF. In both stresses, significant reductions were found in grain yield due to grain number reduction (p<0.05). However, differential responses were found in grain weight depending on the timing and type of stress. S-S reduction increased grain weight only in the 0-15 DAF, while HS no affect grain weight in both timing windows. Grain oil concentration was more stable than protein concentration across treatments. Therefore, these findings suggest that grain weight resilience in rapeseed is greater in early grain filling, at least in the high yielding environment of southern Chile.
climate change, heat stress, source-sink ratio, grain weight, grain number
Exploring the role of the alternative-splicing regulator PRMT5 in temperature responses in plants.Abril San MartínYanovsky, M.J (1)Fundación Instituto Leloir- IIBBA/CONICETThe circadian clock allows plants and other organisms to anticipate daily environmental changes such as temperature, light quality and intensity, and adjust their growth and metabolism to promote fitness. The circadian network is typically described as a transcriptional and translational feedback loop. Recently, however, the post-transcriptional process has been considered essential for circadian regulation. Thermosensitive alternative splicing (AS) of core clock genes has been reported, in which isoform accumulation varies with temperature. For example, high temperatures induce intron retention in some clock core genes, leading to transcript degradation.
In Arabidopsis thaliana, the PROTEIN ARGININE METHYLTRANSFERASE 5 (PRMT5), which methylates arginine residues of histones and spliceosomal proteins, directly links the circadian clock to the alternative splicing. The prmt5 mutant has several circadian alterations, such as a longer period than wild-type plants and a delay in flowering time on long and short days. These phenotypes are partially due to an alteration in the AS of a core clock gene, PRR9. The dual function of PRMT5 as an epigenetic and an alternative splicing regulator makes it an ideal candidate involved in clock-regulated physiological and molecular processes.
We observed that PRMT5 expression increases in response to low temperatures (10ºC), suggesting that it may mediate part of the plant response to the temperature decrease. We are now characterizing the physiological response of the prmt5 null mutant to high and low temperatures by several classical assays such as flowering time, root and hypocotyl elongation, and anthocyanin accumulation, and the molecular responses by analyzing changes in splicing patterns using global transcriptome sequencing (RNAseq).
Understanding the molecular and physiological response to temperature variation is particularly important in the context of climate change.
Circadian clock, PRMT5, alternative splicing, temperature, Arabidopsis thaliana
Unraveling the role of TCP and GLK transcription factors in Arabidopsis seedling developmentAlem, A.L.Gonzalez, D.H.; Viola, I.L.Instituto de Agrobiotecnología del Litoral (IAL), CONICET, UNL. Santa Fe, Argentina.Following germination, exposure to light promotes cotyledon opening and expansion and chloroplast development in a process called de-etiolation. Golden2-like (GLK) proteins are members of the GARP family of MYB transcription factors that play essential roles in chloroplast development. TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors participate in several plant processes, as embryogenesis, germination, flowering, immunity, and hormonal signaling. They can be grouped into two major classes, I and II. In previous studies, we found that Golden2-like 1 (GLK1) physically interacts with several class I TCPs and that the class I protein TCP15 and GLK1 are jointly required for cotyledon opening and the induction of cell expansion and photosynthesis-associated genes during de-etiolation of Arabidopsis seedlings. In this study, we explored the connection between GLK1 and class II TCPs during de-etiolation. We found that a class II TCP mutant showed a delay in the opening of cotyledons after light exposure. Moreover, we observed that expression of light-responsive genes involved in cotyledon opening and chloroplast development was significantly affected in this mutant. However, different to class I TCPs, protein-protein interactions were not detected between the class II TCP members and GLK1. Further molecular and genetic analyses of loss-of-function mutants and gain-of-function constitutive overexpression transgenic lines for these genes revealed a transcriptional regulatory network where these transcription factors interconnect to promote cotyledon opening and the establishment of the photosynthetic apparatus, suggesting that class I and II TCPs integrate into the regulatory network affected by GLK transcription factors by acting at different levels. In summary, this study provides new insights into the coordinated functions of TCP and GLK proteins during Arabidopsis seedling development.TCP transcription factor, GLK1 transcription factor, de-etiolation, cotyledon development, Arabidopsis thaliana
Blooming in the Desert: Unraveling the Secrets of Cistanthe longiscapa's Adaptation.Ariel OrellanaP. G. Ossa (1,2,3), A. A. Moreno (1), D. Orellana (4), M. Toro (1), T. Carrasco-Valenzuela (1), A. Riveros (1,2), C. C. Meneses (2,5,6,7), R. Nilo-Poyanco (8), A. Orellana (1,2)(1) Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile. (2) Instituto Milenio, Centro de Regulación del Genoma, Santiago, Chile. (3) Escuela de Veterinaria, Facultad de Ciencias, Universidad Mayor, Santiago, Chile. (4) Escuela de Agronomía, Facultad de Ciencias Agronómicas, Pontificia Universidad Católica de Valparaíso, Chile. (5) Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago, Chile. (6) Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile. (7) ANID - Millennium Science Initiative Program - Millennium Nucleus for the Development of Super Adaptable Plants (MN-SAP), Santiago, Chile. (8) Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.Understanding how plants adapt to environmental conditions and exhibit phenotypic variability is essential for unraveling their adaptive strategies. The arid Atacama Desert harbors the unique plant species Cistanthe longiscapa, a blooming desert constitutive Crassulacean acid metabolism (CAM) species. This study investigated three sites with diverse soil types and precipitation levels, analyzing nocturnal leaf acid accumulation, δ13C isotopic ratio, photosynthetic pigments, Carbon to Nitrogen ratio, leaf mass per area (LMA), and succulence (SWC) in leaves from each site. Significant differences in these traits were observed, correlating with the varying precipitation recorded for each location. A Principal Component Analysis (PCA) revealed strong associations between specific variables and the geographical segregation of sampling sites.

In addition to ecophysiological investigations, we study the leaf transcriptome of Cistanthe longiscapa through de novo assembly and differential gene expression analysis. RNA-seq reads from 18 libraries were generated from different sites and times of the day. A comprehensive pipeline yielded 88,770 non-redundant transcripts and 37,253 predicted proteins. Gene expression patterns were identified based on location and time of collection through PCA. Differential gene expression analysis highlighted significant changes in transcripts such as the LHY transcription factor, NADP-dependent malic enzyme, and P5CS. Functional enrichment analysis revealed metabolic divergence among sites, with specific processes enriched in different locations.

Overall, this comprehensive investigation sheds light on the ecophysiological and transcriptomic responses of Cistanthe longiscapa to diverse environmental conditions, providing valuable insights into the plant's adaptation mechanisms in the challenging Atacama Desert.

Funding: ANID – Millennium Science Initiative Program – ICN2021_044
CAM, Phenotypic variability, Blooming Atacama Desert, Cistanthe longiscapa, Extremophyle, Transcriptomic analysis, Ecophysiology.
Cytochrome c acts as a positive growth signal in early stages of plant developmentRoldan, Facundo (1)Barrera, Virginia (2); Mansilla, Natanael (1); Gras, Diana E. (1); Canal, M. Victoria (1); Rodriguez, Ramiro E. (2,3); Welchen, Elina (1); Gonzalez, Daniel H.(1)(1) Instituto de Agrobiotecnología del Litoral (CONICET-UNL). Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, 3000, Argentina (2) Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario 2000, Argentina. (3) Centro de Estudios Interdisciplinarios, Universidad Nacional de Rosario (UNR), Rosario 2000, ArgentinaCytochrome c (CYTc) is a soluble heme-protein that serves as an electron carrier in the electron transport chain located in mitochondria. These organelles are capable of sensing and signaling the cellular energy state, coordinating development through interaction with different growth regulatory pathways. We previously studied the role of the two genes encoding CYTc (CYTC-1 and CYTC-2) in plant growth and development. Mutants in CYTC genes show altered shoot and root growth, with smaller rosettes, lower leaf number, delayed flowering and shorter primary roots. Here, we show that these alterations begin in the early steps of plant development and are related to the function of CYTC-1, whose expression is particularly significant in plant meristems. Mutants in this gene show reduced shoot meristematic activity, as indicated by the expression of the meristem growth regulator WUSCHEL. They also show decreased leaf primordium and primary root growth rate, possibly due to a delay in the endoreplication program that results in a decreased cell ploidy. In addition, lack of CYTc affects root architecture, which may be related to changes in auxin distribution. In conclusion, CYTc seems to be a positive signal of growth in roots and shoots, affecting the balance between cell proliferation and growth, as well as hormonal responses.arabidopsis, cytochrome c, mitochondria
A role for a CONSTANS gene homolog in Arabidopsis thaliana developmentMicaela Sol ShalomShalom, M.S. (1); Careno, D.A. (1); San Martín, A. (1); Mateos, J.L. (2); Yanovsky, M.J. (1)(1) Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA-CONICET), Buenos Aires, Argentina. (2) Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Buenos Aires, ArgentinaThe BBX transcription factor family in plants has been characterized due to its importance in the regulation of photomorphogenesis, flowering, shade avoidance and response to biotic and abiotic stresses. One of the most described members of this 32 genes family is CONSTANS (CO, BBX1) which has a key role in the photoperiodic control of flowering. CO has 5 related homologs (BBX2-6) which have not been extensively studied. Here, we managed to obtain Arabidopsis thaliana mutants of CO and its homologous genes by using the CRISPR/Cas9 system and evaluated their role in different physiological processes. We found that under red light conditions photomorphogenesis was altered in the mutants and that its gene expression was down-regulated. Overall, these results contribute to our understanding of the BBX gene family and its crucial role in Arabidopsis development.Photomorphogenesis, BBX, red light, Arabidopsis
Auxin and ethylene are essential in the tomato response to mechanical treatmentCastro Estrada JeniferRamallo A²; Salazar S³; Cabello JV¹; Filippone MP²; Chan RL¹; Welchen E¹¹Instituto de Agrobiotecnología del Litoral (IAL-CONICET-UNL). Cátedra de Biología Celular y Molecular (FBCB-UNL). ²Facultad de Agronomía, Zootecnia y Veterinaria (FAZ-UNT). ³Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Agropecuaria Famaillá (INTA).Tomatoes are preferred and requested vegetables given their taste, nutritional, and antioxidant characteristics. Moreover, their production has enormous importance in several regional economies in our country. Improving this crop yield and fitness may impact family and small farmers’ establishments. Our group has previously shown that a mechanical treatment (MT) on the stem of 12-day-old tomato seedlings for 48 h resulted in a 25-30% enlargement of stem diameter, increasing fruit production. Upon histological analysis of stem cross-sections, we observed an increase in the stele area with morpho-anatomical modifications in the vascular bundles, which together with other unknown factors, conferred plant tolerance against Fusarium oxysporum (Fol). At the molecular level, we observed an induction of the expression of genes encoding for the Ethylene-forming enzyme SlACC and Auxin transporters SlLAX1 and SlLAX2, after the MT. To investigate the possible involvement of these hormones, we treated Ailsa Craig (AC) seedlings to MT with ethylene (ET) precursor ACC (10mM), a pathway inhibitor AgNO3 (100 µM), and auxins IAA (1 mM), a polar transport inhibitor NPA (1mM) for 48 h. The results indicated that both hormonal pathways are connected with the tomato response to MT. Moreover, we found that tomato mutants less sensitive to ET and auxins, Never ripe (Nr), and diageotropic (dgt), respectively, did not exhibit an increase in stem diameter after MT. Additionally, a double mutant between an ET-overproducer plant (epinastic, epi) and dgt (dgt/epi) did not incremented their stem diameter. In contrast, the epi and entire mutants, lacking an auxin signal repressor, showed wider stems

Altogether our observations strongly suggest that auxin is essential for MT response, and ethylene plays a crucial role too.
Tomato, mechanical treatment, phytohormones, mutants.
Targeted disruption of tomato CYC-B gene improves postharvest color development and cold stress toleranceArruabarrena, A. (1)Duvois, V. (1); González-Arcos, M. (1); Vidal, S. (2) and Lado J. (1)(1) Estación Experimental INIA Salto Grande, Instituto Nacional de Investigación Agropecuaria (INIA), Salto, Uruguay. (2) Laboratorio de Biología Molecular Vegetal, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.Red color development is a very important fruit quality trait in tomato breeding, especially during postharvest storage. When exposed to low temperatures, tomato fruits are sensitive to cold and develop chilling injury (CI). Lycopene is the main pigment present in tomatoes and is responsible for its red color. In other cold-sensitive fruit, it has been described that lycopene contributes to alleviating CI disorder during postharvest cold storage. Therefore, increasing lycopene content in tomato fruit could enhance its cold stress tolerance in addition to improving fruit quality.
In tomato, og and ogc mutants have high lycopene content in fruit because these alleles encode for non-functional CYC-B enzymes and are unable to transform lycopene into β-carotene. These natural mutations have not been found in indeterminate growth tomato germplasm because they are linked to the sp mutant allele that is responsible for determinate growth habit. In greenhouse production of fresh market tomatoes, indeterminate growth is preferred in many countries, including Uruguay. In this work, we used CRISPR-Cas9 to generate CYC-B non-functional fruit-specific enzymes in tomato lines exhibiting indeterminate growth habit. We compared the postharvest color development of ripening fruit from edited and non-edited plant lines and evaluated CI symptoms during cold storage in autumn 2022 and 2023. Fruits from edited plants showed earlier and more uniform red color development during ripening at 25°C as well as a lower chilling injury incidence during cold storage. This work suggests that an earlier and higher accumulation of antioxidants such as lycopene contributes to reducing tomato CI during postharvest cold storage.
CRISPR-Cas9, Solanum lycopersicum, chilling injury, fruit quality
Characterization of HHO5, a transcription factor mediating nitrogen response in Arabidopsis and riceFrancisco RomeiMariana ObertelloInstituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres”, CONICET, ArgentinaPlant nitrogen use efficiency is a major issue due to high economic and environmental costs in the use of nitrogen fertilizers in agronomic production of crops. However, little is known about molecular mechanisms regulating plants response to nitrogen availability.

Interest in HHO5 gene lays on a previous work where we demonstrated with a systems biology perspective that it plays an important role as a transcription factor in the nitrogen response regulatory network, being expressed in the plant when nitrogen is supplied in both A. thaliana and O. sativa (Obertello et al., 2015).

Evidence was found that HHO5 loci in A. thaliana and its orthologous in O. sativa could also be regulating responses to environmental cues other than nitrogen presence such as water or salt stress in plants. This was the result of an in silico analysis of the promoter region where we found conserved sites in both species with sequences related to abscisic acid (ABA) response.

To test this hypothesis we used two A. thaliana knock-out lines (hho5). Germination experiments exposing seeds to ABA or salt stress showed lesser response in hho5 mutants compared to wild type plants. In addition, we design genetic constructs containing A. thaliana endogenous promoter region (1Kb or 3Kb) regulating the expression of O. sativa cDNA (OsHHO5) fused to reporter genes or reporter gene only under the control of the promoter. The transgenic Arabidopsis plants carrying these constructs were exposed to different treatments of N and ABA to understand HHO5 regulation. We also generated transgenic Arabidopsis plants overexpressing HHO5 fused to GFP.

Our results suggested that HHO5 may be involved in abiotic stress response and that N availability leads the expression of HHO5 in vascular tissue of the rosette leaves of transformed plants. Also, HHO5 was shown to behave as a transcription factor being translocated to the nucleus in the roots cells.
gene regulation, nitrogen methabolism, stress response
RNA silencing pathways in plantsNicolas BolognaNicolas BolognaCRAG. Barcelona

RNA silencing controls gene expression via 19-36 nucleotide small RNAs (sRNA) to regulate development, control stress responses, and preserve genomic integrity, among other essential processes. To fulfil their biological function, sRNAs are loaded into ARGONAUTE (AGO) proteins. The number of AGO genes varies among different organisms. The Arabidopsis thaliana genome encodes ten At-AGO, which can be grouped in three major phylogenetic clades. Whereas At-AGO1, -5, and -10 clade binds ~21nt molecules acting in cytoplasmic post-transcriptional silencing, the clade formed by At-AGO4, -6, -8, and -9 associates with 24nt sRNA mediating nuclear transcriptional silencing. A third clade composed of At-AGO2, -3, and -7 performs different functions including antiviral defense, tasiRNA biogenesis, and DNA repair. Since the discovery of the first eukaryotic AGO in Arabidopsis, our understanding of these proteins has grown exponentially throughout all the eukaryotes. However, many aspects of AGO proteins’ modes of action and how they are influenced by their subcellular localization are still to be elucidated. Here, we provide an updated view of the subcellular localization and shuttling mechanism of AGO proteins in plants.

TCP transcription factors fine-tune chlorophyll biosynthesis to prevent photo-oxidative damage during de-etiolation in Arabidopsis thalianaRocío Micaela JureAlem, A. L.; Viola, I. L.; González, D. H.Instituto de Agrobiotecnología del Litoral (IAL) – CONICET – UNL.During de-etiolation, dark-germinated seedlings face a challenge when transitioning to light, as light can be harmful to the plant. In preparation for this switch, dark-grown seedlings accumulate the chlorophyll precursor protochlorophyllide (Pchlide) to allow rapid assembly of a functional photosynthetic machinery upon initial light irradiation. Once the seedlings are exposed to light, Pchlide is converted to chlorophyllide, which is subsequently esterified to produce chlorophyll. Nevertheless, free Pchlide acts as a photosensitizer upon light exposure, producing reactive oxygen species (ROS) and thereby causing photooxidative damage, which affects cellular structures and, eventually, the growth or survival of the plant. Therefore, plants have evolved efficient mechanisms to carefully regulate the levels of Pchlide in the dark. In this study, we observed that plants with loss-of-function in members of the TEOSINTE BRANCHED 1, CYCLOIDEA, and PROLIFERATING CELL FACTORS (TCP) family of plant transcription factors show increased photodamage and ROS accumulation during de-etiolation. This is correlated with higher levels of protochlorophyllide and increased expression of genes that encode proteins involved in chlorophyll biosynthesis in etiolated plants. The effect of mutation of the TCPs was counteracted by treatment with gibberellin (GA) or overexpression of the transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4), a repressor of the expression of chlorophyll biosynthesis genes, suggesting that the TCPs affect GA metabolism or responses upstream of PIF4. Related to this, mutants in the TCPs show reduced expression levels of genes that encode GA biosynthesis enzymes. Altogether, our results indicate that TCP transcription factors fine-tune the biosynthesis of chlorophyll precursors in etiolated plants and during de-etiolation, affecting GA metabolism and the activity of PIFs.Arabidopsis thaliana, Photodamage, De-etiolation, TCP, PIF.
The miR394 pathway in tomato fruits and its role in the response to Botrytis cinereaGonzález-Muñoz, J.C. (1)Favaro M. A. (1); Civello, P. M (2); Dotto, M. C. (1)(1) ICIAGRO Litoral (CONICET-UNL), Facultad de Ciencias Agrarias (UNL), Esperanza, Argentina. (2) INFIVE (CONICET-UNLP), La Plata, ArgentinaTomato gray mold is a common disease caused by the necrotrophic fungus Botrytis cinerea which causes fruit decay and reduces fruit storage quality. The miR394 pathway is conserved among plant species as well as its target transcript LEAF CURLING RESPONSIVENESS (LCR), which encodes a F-box protein. The miR394/LCR regulatory module has been shown to participate in several biological processes, including biotic stress response. To date, it has been shown that this regulatory pathway is involved in the response to B. cinerea infection in tomato leaves and that Arabidopsis lcr plants or plants overexpressing tomato miR394 are more susceptible to this infection. However, no information regarding fruit infection is currently available. Taking into consideration the importance of gray mold during postharvest and commercialization of tomato fruits, the need arises to analyze whether this regulatory pathway plays a role in B. cinerea infection also in fruits, the main commercial product of this species. Based on existing literature, we identified a single locus in the tomato genome coding for each miR394 and LCR and updated the genomic information for both genes using the latest available version of the tomato genome (v.4.0). A postharvest infection experiment was conducted with tomato fruits (S. lycopersicum cv. Micro-Tom) inoculated with B. cinerea and stored under controlled conditions for 7 days. We analyzed lesion diameter and damage severity daily and evaluated LCR expression by semiquantitative RT-PCR in mock-treated and infected tomato fruits collected at 0, 3 and 7 days post infection (dpi). We observed that in our experimental settings, LCR expression was down-regulated at 3 dpi in infected fruits compared to mock-treated fruits, which coincides with the onset of visible necrotic lesions in infected fruits. Thus, here we report initial evidence of participation of the miR394 pathway in the response to B. cinerea infection in tomato fruits.Botrytis cinerea, biotic stress, tomato, miR394, LCR.
Does an increase in available nitrogen during the seed-filling period improve soybean seed physiological quality under field water deficit?Ergo, Verónica Vanesa (1)Gallo, C.D.V. (2); Salvagiotti, F. (2,3); Carrera, C.S. (1,3,4)(1) Unidad de Estudios Agropecuarios (UDEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Córdoba, Argentina. (2) Estación Experimental Agropecuaria INTA Oliveros, Santa Fe, Argentina. (3) CONICET, Argentina. (4) Department of Agricultural and Forest Sciences and Engineering, University of Lleida AGROTECNIO (Center for Research in Agrotechnology), Lleida, Spain.Increasing or maintaining yield and seed physiological quality under water deficit (WD) conditions is challenging for agriculture under the current climatic change scenario. The aim of this study was to evaluate the increase in nitrogen (N) availability on seed physiological quality under WD during seed filling in soybean genotypes contrasting in seed protein concentration. We conducted a field experiment testing a high (42%, HP) and low (38%, LP) seed protein genotypes under irrigation and WD conditions (soil water content ≤ 25% of field capacity from R5, beginning seed filling) and two N levels: non-fertilized (N0) and fertilized (+N, 600 kg N ha-1 as fertilizer equally split at vegetative, beginning bloom, and beginning pod). At harvest seed physiology characterization (vigour, viability, and environmental and fracture damage variables) was determined by topographic tetrazolium test. Seed weight was also measured. The HP genotype showed higher seed weight (23%), viability (11%) and lower vigour (28%) than the LP genotype across water availability and N treatments. Under WD (regardless of N and genotypes), seed weight, vigour and viability significantly (p ≤ 0.05) decreased by 28, 14, and 20%, respectively; whereas seed damage due to environmental conditions was 35% higher compared to irrigation treatment. Independently of water availability and genotypes, +N treatment significantly (p ≤ 0.05) increased the vigour (14%) and decreased the viability (14%). The +N treatment also increased the fracture damage (40%), affecting the vigour but depending on the seed region damaged. Interestingly, we observed in HP genotype that +N × WD combination increased both, seed weight (14%) and vigour (61%). Although our results show that WD during seed filling produced severe damage in seed physiology attributes, the addition of +N mitigated this abiotic stress by increasing seed weight and vigour, mainly in the HP genotype.Glycine max, seed vigour, seed viability, seed damage, drought, nitrogen
Do soybean plants exhibit drought stress memory?Vannay, Gustavo Javier (1)Otegui, M.E. (2); Chan, R.L. (1); Capella, M. (1)(1) Instituto de Agrobiotecnología del Litoral, CONICET, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina (2) CONICET-INTA-FAUBA, Estación Experimental Pergamino, Facultad de Agronomía, Universidad de Buenos Aires. Av. Frondizi (Ruta 32) Km 4.5, 2700 Pergamino, ArgentinaPlants are exposed to fluctuating intermittent stressful conditions and might acquire the ability to “remember” those events to be better prepared for subsequent exposures. Such ability was previously described by other authors in several species, particularly for heat stress and at the molecular level, and named stress memory. In other words, some genes are differentially expressed after one or two stress shocks. We wondered whether this memory could play a role in the performance of soybean plants in response to water deficit, the most harmful stress impacting seed yield. Two sequential drought stress treatments were applied to soybeans (Williams 82 and Williams HB4) grown in culture chamber and in the field during the 2022-2023 campaign. The expression of some transcription factors from the HD-Zip I family, such as GmHB12-1 and GmHB6-1, was differentially regulated when 14-day-old soybean plants were exposed to repetitive dehydration stress episodes, suggesting that they might be response memory genes. However, the healthier aspect and the lower water loss of primed plants (grown in the culture chamber) compared with those subjected to a sole treatment was due to the difference in their leaf area of approximately 30 %. Yield components and grain production were assessed in the field assay, resulting in non-significant differences between primed and non-primed plants. These observations, albeit limited by only one assay condition, were independent of the genotype. Altogether, our results suggest that soybeans plants do not present a memory behavior, at least in the assayed conditions. Further studies must be performed to determine in which developmental stage, plants have memory or if this response is limited to high temperatures.Drought, homeodomain leucine-zipper I (HD-Zip I), soybean, stress memory, plant physiology, molecular biology
Differentiation of soybean quality parameters according to production environment: linkage to the originCarpaneto, BárbaraEiza, M. (1); Montoya, M. (1); González Belo, R. (2); Izquierdo, N. (2); Quiroz, F. (1)(1)Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible (IPADS), Balcarce, Argentina. (2) Facultad de Ciencias Agrarias (FCA) – Universidad Nacional de Mar del Plata (UNMdP)Soybean grain composition is determined by genotype, environment, and their interaction. Their combination determines the specific quality and potential of products linked to origin. Soybean quality parameters (protein and oil content) varies through the years under producing area. Due to there are few reports available for SE of Buenos Aires (SEBsAs) area, we set the goal as to quantify quality parameters from soybean produced in different environments in the SEBsAs, hypothesizing that concentration of both grain components is associated with the environments where they are produced.

During 2021/22 261 soybean grain samples were collected from commercial fields of the SEBsAs producing area. Quality parameters were determined by near infrared spectroscopic technology. The contribution to the total variability for protein and oil content was 53% and 59% (environment) and 16% and 7% (genotype), respectively. Protein concentration varied between 32,4% and 41,7%, while oil concentration between 18,2% and 24,7%. A significant reduction in oil content (-0,9%) and a non-significant increase in protein content (+0,5%) were found for second crop soybeans (later planting dates), compared to first crop soybeans.

Significant regressions were found for relationship of meteorological and location variables with protein content, and those variables would influence soybean protein content additively, as part of a more complex model. Overall, these results show that concentration of protein and oil in soybeans from the SEBsAs were associated with production environment. These findings would make possible to differentiate crop quality according to the environment, and to work for a denomination of origin. These studies should be continued to determine more accurately the effect of the environment on grain quality, identify other quality-related variables linked to the producing origin and promote differentiated local production.
soybean, protein, oil, environment, southeast of Buenos Aires, denomination of origin
Understanding the thermal regime and cultivar effects on quality parameters in olive fruits using a field network with contrasting Argentinian growingMariela Torres (1)Pierluigi Pierantozzi1, Cibeles Contreras1, Martín Tivani1, Valerio Mastio1, Luciana Gentili1, Agustin González Gilyam1, Peter Searles2, Magdalena Brizuela2, Fabricio Fernández3 Alejandro Toro4, Carlos Puertas5, Eduardo Trentacoste6, Juan. Kiessling7, Damián Maestri8(1) Estación Experimental Agropecuaria San Juan, Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Juan, Argentina (2) Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR, Provincia de La Rioja, UNLaR, SEGEMAR, UNCa, CONICET), La Rioja, Argentina (3) Estación Experimental Agropecuaria Catamarca, Catamarca, INTA, Argentina (4) Estación Experimental Agropecuaria Cerro Azul, Misiones, INTA, Argentina (5) Estación Experimental Agropecuaria Junín, Mendoza, INTA, Argentina (6) Estación Experimental Agropecuaria La Consulta, Mendoza, INTA, Argentina (7) Agencia de Extensión Rural Centenario, Neuquén, INTA, Argentina (8) Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Córdoba (UNC).Some olive cultivars and production regions around the world, although they may provide good quality olive oils, may not comply with the current commercial regulations establishing acceptable levels of either major (e.g. fatty acids) or minor (e.g. sterols) compounds in extra virgin olive oils. The present study was driven by the hypothesis that olive growing environments, differing in thermal regime conditions, affect main fatty acids, squalene and sterol contents of olive fruits. On the basis of differences in agronomic characteristics and oil composition, two olive cultivars (Arbequina and Coratina) were selected and sampled at different fruit development stages. Various models were examined to look for relationships between environmental thermal records and aforementioned chemical parameters; those including the accumulated thermal time (ATT) and minimum temperatures showed the best fit. In both cultivars, oleic and linoleic contents were negatively associated with ATT throughout the development and ripening stage of the olive fruit, being this trend more noticeable in Arbequina. On the other hand, the total and individual sterol contents were positively associated with ATT over all the fruit development and ripening period considered. In all cases, the data from Arbequina fit the models better than for Coratina and differences between cultivars in major and minor compounds contents were greater in the warmest growing environments. Overall, findings indicated a strong impact of the growing environment on the contents of these compounds. Such an effect was associated with specific thermal characteristics of the olive growing sites; it was observed that oleic, total and individual sterol concentrations were found to be lower and higher in the warmer northernmost sites than in the cooler southernmost ones, respectively. There was also an effect of the cultivar, particularly on the contents of palmitic, oleic, linoleic, β-sitosterol, campesterol and total sterols.Olive fruits, squalene, fatty acids, sterols, thermal regime, growing environments
Changes in the development and numerical components of reproductive primordia associated with genetic improvement in barleyComacchio, Julián Ezequiel (1)Ibañez, C. (1); Abeledo, L.G. (1,3); Miralles, D.J. (1,2)(1) Facultad de Agronomía, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina. (2) Instituto de Fisiología y Ecología Vinculado a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas (IFEVA-CONICET), Ciudad de Buenos Aires, Argentina. (3) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.The analysis of the impact of genetic improvement on physiological traits in barley identifying potential attributes is relevant to enhance future genetic gains in the crop. The objective of this study is to characterize the changes in vegetative and reproductive development in response to factors that regulate the duration of ontogenic stages (temperature, vernalization, and photoperiod) in commercial barley cultivars released in the Argentine commercial market over the last 40 years. Field experiments were conducted at the School of Agriculture FAUBA (campaign 2022/23), evaluating 12 commercial barley cultivars released in Argentine from 1982 to 2021, across 5 sowing dates. External phenology was monitored following the Zadoks scale (1974), and reproductive organs at meristematic level following the Waddington scale (1983). Cycle duration was significantly shortened with delays in sowing dates (P=0.0001), with different rates depending on the genotypes (P<0.05). Delays in the sowing date shortened all pre and post-anthesis stages for all varieties (P<0.05). At optimum sowing date the cycle length was lengthened with the year of release of the genotypes but the differences were not significant (P>0.1). At meristematic level, the shortening of the First Visible Node-Anthesis stage reduced the duration of the stage of floral primordia differentiation (P=0.0001), with differences between old (prior to 1999) and modern genotypes (after 2011). Modern cultivars prolonged the duration of the primordia differentiation stage, initiating the floral primordia earlier (P=0.019), and finishing later (P=0.009) than the older cultivars. Regarding the rate of differentiation of these reproductive structures, old cultivars exhibited a higher rate compared to modern ones (P=0.003). However, the higher rates did not compensate the shorter duration of the primordia differentiation, resulting in a lower maximum number of reproductive structures on the main stem in old cultivars compared to modern ones (P=0.0007).malting barley, genetic improvement, vegetative and reproductive development.
Role of GRP1a in tomato fruits: response to different postharvest conditions and possible targets for interaction and mRNA stabilizationDenhoff A. M. LourdesBustamante Claudia (1), Drincovich María Fabiana (1), Müller Gabriela (1).(1) CEFOBI-UNR, Rosario, Argentina.Tomato is one of the main food crops worldwide. The commercialization of these fruits is from the mature green stage at temperatures between 12-15ºC. Although lower temperatures delay ripening, allowing marketing, they induce cold damage affecting fruit quality.
Glycine-rich RNA-binding proteins (GRPs) are involved in the regulation of gene expression at the post-transcriptional level. In our lab, transgenic tomato plants cv Microtom that express the GRP1a protein from the mature green stage (PG-preGRP1a plants) have been obtained. The fruits of these plants have been characterized as having a higher protein content, compared to fruits of wild type (WT) plants, when these were stored for 7 days at 4ºC. In this work, progress was made in the knowledge of the response of WT and transgenic tomato fruits (PG-preGRP1a plants) under prolonged cold postharvest storage. Consequently, fruits were harvested at the yellowish mature green stage (D0) and stored at 4ºC (damage-inducing temperature) and 15ºC (control temperature) for 21 days. Storage of tomato fruits at 4°C for 21 days delayed ripening and also induced cold damage, which was greater in WT fruits compared to transgenic fruits. This damage is exacerbated by storing the fruits at room temperature 1 day after treatment. Fruit samples were collected under the different treatments and prior to them (D0) for evaluation. Proteome analysis of the different genotype fruits and conditions help to explain the phenotypes observed in WT and PG-preGRP1a fruits.
Differential proteins were identified, particularly in the fruits of PG-preGRP1a plants subjected to treatments that induce cold damage. Quantitative real-time PCR of the corresponding coding transcripts allows addressing the hypothesis that suggests the formation of stabilized mRNA-GRP1 complexes, allowing the RNA processing and translation. In conclusion, this study reveals new objectives that improve the shelf life and quality of fruits stored at low temperatures.
Cold postharvest, GRP1a, mRNA-GRP1 complexes, chilling injury.
Circadian clock functions in woody perennialsPerales, M. (1,2)Allona, I. (1,2); Conde, D. (1); Alique, D. (1); Gomez-Soto, D. (1)(1) Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) ‐Centro Nacional Instituto de Investigación y Tecnología Agraria y Alimentaria, CNINIA (CSIC), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain. (2).Departamento de Biotecnología‐Biología Vegetal, Escuela Técnica Superior Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), 28040 Madrid, Spain.ver resumen adjuntoCircadian Clock, Poplar, Woody Perennials, photoperiod, winter dormancy, seasonality
Interplay between cytochrome c and hormones during early plant developmentGras, D. E. (1)Coronel, F.P. (1); Canal, M.V. (1); Welchen, E. (1); González, D.H. (1)Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Universidad Nacional del Litoral Santa Fe, ArgentinaWe studied the effect of reducing the levels of the mitochondrial electron carrier cytochrome c (CYTc) in Arabidopsis.  Energy production through oxidative phosphorylation is one of the main processes that take place inside mitochondria. Oxidative phosphorylation is performed by the sequential operation of complexes (I–V) located in the inner mitochondrial membrane. In addition to these complexes, CYTc catalyzes the transfer of electrons from complex III to complex IV. Phenotypic analysis of mutant and overexpression lines suggested that CYTc is a positive regulator of hypocotyl elongation. Changes in hypocotyl growth mainly result from changes in longitudinal cell elongation. Accordingly, cytc mutants show a decrease in hypocotyl cell length, relative to the wild type. We show that the defect in cytc mutants is rescued by exogenous application of brassinosteroid (BR) and auxin (AUX). In addition, cytc mutants exhibit altered sensitivity to a BR biosynthesis inhibitor and the polar auxin transport inhibitor NPA, suggesting that AUX and BR homeostasis are affected. The gain-of-function mutation bzr1-1D suppresses the elongation defect of cytc mutants indicating that BZR1 acts downstream of CYTc in promoting plant growth. Previous studies have shown that BZR1 directly interacts with PIF4, and this complex controls cell elongation and hypocotyl growth. Our results suggest that CYTc is capable of regulating the elongation of Arabidopsis hypocotyls acting via the BZR1PIF4 complex.Mitochondria, Hormones, Hypocotyl growth
NO Way Out: Nitric Oxide Blocks AutophagyBellis Pedro (1)Lascano Ramiro (1,2); Robert German (1,2.3)(1) Stress Biology Group, Unidad De Estudios Agropecuarios, INTA-CONICET, (2) Laboratorio y Cátedra de Fisiología Vegetal, FCEFyN-UNC, (3) Insituto de Fisiología y Recursos Genéticos Vegetales, CIAP-INTAAutophagy is a conserved key process related to the development, stress responses, and remobilization in plants and eukaryotes in general. It is well established that nutrient deficiency conditions induce autophagy. Although certain molecular components that regulate the activation of this process have been elucidated, the signal transduction pathways governing the molecular machinery remain underexplored. In this study, we investigated the effects of nitric oxide (NO) as a possible regulator of autophagy. NO is a free radical produced as a byproduct of the enzyme Nitrate Reductase (NR) during the reduction process of nitrates. It functions as a second messenger, playing a crucial role in various developmental and stress response processes. Our results showed a correlation between nitrate availability, NR activity, NO levels, and the regulation of the autophagic process. To further investigate the impact of NO on autophagy modulation, we employed pharmacological approaches, including treatments with the NO donor SNP and the NO scavenger cPTIO. Our findings demonstrated that NO effectively inhibits autophagy activation in response to both nutrient deprivation and pharmacological inhibition of the target of rapamycin (mTOR). Conversely, scavenging NO leads to a slight increase in autophagy under nitrate-sufficient conditions. To address the mechanistic of NO in the regulation of autophagy, we explored putative S-nitrosylation sites in key components of the autophagy machinery through in silico analysis. Currently, we are evaluating the effects of NO on the activity of the redox-sensitive ATG4 protein, which has been shown to be inhibited by S-nitrosylation in mammals. By integrating the physiological aspect of nitrate reduction and NO production with molecular mechanisms, our study provides a comprehensive understanding of how the autophagic process is modulated by nitrogen availability.autophagy, nitrate, nitric oxide,
Regulation of vitamine E metabolism in tomatoCarrari, F.(1)De Luca, M.B.(2); Santoro, L.(1); Vasulka, M.(1); Zoraire, C.(1); Castro, I.(1); Echeverri, M.(1); Cernadas, A.(1); Asis, R.(3)(1) Instituto de Fisiología, Biologia Molecular Molecular y Neurociencias, CONICET, Argentina. (2) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, CONICET, Argentina. (3)Centro de Investigación en Bioquímica Clínica e Inmunología, CONICET, Argentina.The genetic bases of the yield-associated traits and nutritional values of crop plants have been studied in several species but are largely restricted to classical molecular genetic analyses and less effort have been devoted to uncover epigenetic mechanism(s) underlying these traits. Our research group study the regulation of biochemical pathways that ultimately impact these kinds of traits in tomato plants. Three main issues will be discussed in this presentation: 1) analyses of the epigenetic nature of the regulation of metabolite content variations in tomato focusing on the vitamin E pathway; 2) results from metabolic engineering strategies of cholorophyll recycling pathways and 3) an overview on fundamental knowledge about the molecular mechanisms determining hybrid vigor (heterosis) in plants.tomato, epigenetics, chlorophyll metabolism, hybrid vigor
High temperature improves photosynthetic electron transport but reduces stomatal conductance in flooded tomato plantsSánchez, Carlos Leonardo RubénVidoz, M.L ; Mignolli, FIBONE. FCA (UNNE)The combination of two or more adverse climatic events may have severe effects on crops since
the negative consequences of each stress could add up. This work studied the effect of the
combination between high temperature and flooding on the photosynthetic adjustments in
tomato leaves. Tomato plants of the cv Ailsa Craig were maintained under regular irrigation and
flooded conditions and at either an optimal temperature of 25.8 ºC ±1.0 (OT) or high temperature
of 35.8 ºC ±2.3 (HT). After six days, stomatal conductance and chlorophyll fluorescence
measurements were performed with an SC-1 portable porometer (Meter-group) and a
fluorometer (PocketPea, Hansatech). In HT-flooded plants, we observed signs of severe wilting in
the apical part, a lower height and more signs of senescence of basal leaves compared to plants
flooded at OT. Flooding stress caused a more substantial decrease in stomatal conductance in HT-
flooded plants, while no difference in photosystem 2 (PSII) fluorescence parameters was observed
in comparison with OT-flooded plants. However, J 0 RE1 /RC, (Electron transport flux until PSI
acceptors per PSII), J 0 RE1 /J 0 ET2 (Efficiency/probability with which an electron from Quinone B is
transferred until PSI acceptors), J 0 RE1 / J ABS (Quantum yield of the electron transport flux until the PSI
electron acceptors) and DF total (Driving force on absorption basis) were significantly higher in HT
than in OT plants, suggesting an enhanced flow of electrons towards the final photosystem I (PSI)
acceptor. If, on the one hand, high temperature makes the transfer of electrons along the
transport chain more efficient, on the other hand, gas exchange is more severely impaired due to
flooding. Therefore, in plants subjected to flooding under high temperatures, the high flow of
electrons could exacerbate the risk of photooxidative damage as the limitation of stomatal
conductance and CO2 supply might hamper downstream reactions, i.e. the Calvin–Benson cycle.
Tomate, High temperature, Flooding stress, Photosynthesis
Supplemental irrigation improves seed yield of a range of soybean cultivars in Entre RíosCarolina Alaluf (1)De Battista, J.J.(2); Puhl, L.E.(3); Rondanini, D.P.(3)(1) Facultad de Ciencias Agrarias, UCU, (2) EEA Concepción del Uruguay, INTA; (3) Facultad de Agronomía, UBADrought is a main constrait to growing soybean in Entre Ríos. The objective was to evaluate the benefits of supplemental irrigation (SI) on seed yield and its components of a range of soybean cultivars. A field trial was carried out during two seasons (S1: 2012/13 and S2: 2014/15) at the EEA INTA Concepción del Uruguay, using 9 high-yielding cultivars (the 3 highest yielding of the 3 maturity groups best adapted to the area according to RECSO data). Experimental design was split-split plot with water treatment (SI or rainfed) in the main plot, and cultivar in the subplot. SI was 132 mm supplied during the critical reproductive period (R3-R6). The cumulated rain from November to April was 634 mm (a dry year) for S1 and 760 mm for S2 (a wet year). Total biomass was increased by SI in both seasons. SI significantly increased seed yield in S1 (+786 kg/ha on average) in a similar magnitude for all cultivars. Seed number and pods (per area and per plant) were increased for SI. For S2 there were no significant effects of water treatment nor cultivar son seed yield. Seed weight was significantly affected by water and cultivar in both S1 and S2. It is concluded that under water limitations, SI improves the seed number and seed yield. The seed weight had high sensitivity to the water environment and variability between cultivars.soybean, seed yield, water supply, seed number, seeg weight, GxE interaction
Does the altered expression of HD-Zip I transcription factors in roots affect soybean plants’ fitness?Caraballo M., L.N. (1).Raineri, J. (1); Chan, R.L. (1).(1) Instituto de Agrobiotecnología del Litoral, CONICET-UNL, Santa Fe, Argentina.Plants are continuously subjected to stress factors that impact their fitness and yield. Among them, water deficit and salinity are the most harmful. The adaptation to adverse environmental conditions depends on the species and is modulated by different biomolecules, triggering signal transduction pathways that help respond to the stress. At the transcriptional level, transcription factors (TFs) play crucial roles in such responses. The homeodomain-leucine zipper I (HD-Zip I) TFs subfamily members, unique to plants, have been shown as master-switch developmental regulators in normal and stress conditions.
Aiming to identify potential genes that could be used in crop improvement, we searched for HD-Zip I members in the soybean genome. We selected several members for expression studies, and soybean seedlings were grown in normal and stress conditions, namely under water deficit and high salinity. Among the tested genes, some responded early to one or two of these treatments, whereas others did the same ten days after. Concurrently, a hairy roots transformation protocol was established for obtaining chimeric transgenic soybean plants with a root system that bears genetic constructs able to express or silence the genes of interest. Moreover, a fast-screening method was set for analysing positive transgenic roots in situ.
Currently, we are evaluating chimeric plants overexpressing Gmhdz32 in their roots. We performed phenotypic and molecular analyses in the greenhouse. Putative target genes of the altered root TFs were assessed in the aerial part of plants, aiming to elucidate a possible impact of the transformed roots. Simultaneously, we are generating additional constructs, both to overexpress and silence members of this TFs family. This study aims to provide a characterization of the effects that soybean plants might have from a modified expression of endogenous HD-Zip I genes, some of which could become potential biotechnological tools for crop improvement.
Transcription factors, HD-Zip I, soybean, hairy roots, plant biotechnology.
Polymorphic inverted repeats near coding genes impact chromatin topology and phenotypic traits in Arabidopsis thalianaAgustín L. Arce (1,5)Regina Mencia (1,5), Damian A. Cambiagno (1) Patricia L. Lang (2), Chang Liu (4), Hernán A. Burbano (2,3), Detlef Weigel (2), Pablo A. Manavella (1)(1) Instituto de Agrobiotecnologíaa del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina. (2) Department of Molecular Biology, Max Planck Institute for Biology Tuübingen, 72076 Tübingen, Germany. (3) Centre for Life’s Origins and Evolution, University College London, London, UK. (4) Department of Epigenetics, Institute of Biology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany. (5) These authors contributed equally.Transposons are mobile elements that are commonly silenced to protect eukaryotic genome integrity. In plants, transposable element (TE)-derived inverted repeats (IRs) are commonly found near genes, where they affect host gene expression. However, the molecular mechanisms of such regulation are unclear in most cases. We recently studied these IRs in Arabidopsis thaliana (doi:10.1016/j.celrep.2023.112029) and showed that their expression is associated with the production of 24-nt small RNAs which trigger DNA methylation of the IRs through the RNA-dependent DNA methylation (RdDM) pathway. This process can be initiated by the RNA Polymerase II and be independent from RNA-dependent RNA polymerases, since IR transcripts fold into hairpin loops. Using mutants in the RdDM pathway, we showed that these IRs are responsible for drastic changes in local 3D chromatin organization. Notably, many of the IRs differ between Arabidopsis thaliana natural accessions, causing variation in short-range chromatin interactions and gene expression. CRISPR-Cas9-mediated disruption of two IRs leads to a switch in genome topology and gene expression with phenotypic consequences. Our data show that the insertion of an IR near a gene provides an anchor point for chromatin interactions that profoundly impact the activity of neighboring loci. This turns IRs into powerful evolutionary agents that can contribute to rapid adaptation.MITE, transposon, inverted repeat, small RNA, chromatin loop, DNA methylation, chromatin organization, RdDM, natural variation, CRISPR/CAS9
Strategies for peanut smut control (Thecaphora frezii): resistant genotypes, a calcium amendment and bacterium Bacillus sp. CHEP5Marcellino, Natalia (1,2)Rovere, M.E. (1); Loser, U.A. (1); Peiretti, E.G. (2) Bongiovanni, M.D. (1); Ibañez M.A. (1); Tonelli, M.L. (1)(1) Instituto Nacional de Investigaciones Agrobiotecnológicas, UNRC-CONICET, Argentina. (2) Departamento de Producción Vegetal, FAV-UNRC, Argentina.ver resumen adjuntopeanut smut, calcium amendment, genetic resistance, biocontrol bacteria.
Relationships between reactive oxygen species and growing variables of Pistum sativum L., under different soil moisture levelsMichel, AnaliaMichel, A. (1,2); Appelhans, S. C. (1,3); Sequin, C. J. (1,2); Bianchi, M. (1,2); Trossero, J. A. (1,2); Caviglia, O. P. (1,2)(1) Facultad de Ciencias Agropecuarias, Universidad Nacional de Entre Ríos. (2) CONICET. (3) INTA, EEA Paraná, Entre Ríos.Low aeration capacity of soils may impact biological nitrogen fixation, especially in waterlogging-sensitive species like Pisum sativum L. It is well recognized that root nodules exhibit intense biochemical activity and that the production of reactive oxygen species (ROS) is influenced by this activity. However, little is known about how soil low aeration capacity affects nodulation and how it impacts ROS production in other plant organs, such as stipules. The aims of this study were: 1) to evaluate the effect of different levels of soil aeration on nodulation, and 2) to assess the effect of nodulation on ROS production and antioxidant enzyme activity throughout the stipules of P. sativum. A greenhouse study was conducted to evaluate P. sativum plants growing and ROS production under two different soil moisture levels, 100% and 60% of soil field capacity (100% FC and 60% FC, respectively). After 30 days of pot irrigation, number and weight of nodules, leaf area index, and aerial and root biomass were measured. ROS measurements included the determination of hydrogen peroxide (H2O2) concentration and superoxide (O2-) concentration in stipules. Ascorbate peroxidase (ASP) and catalase (CAT) enzymatic activity were also measured. Number of nodules, aerial and root biomass were significantly higher for 100% FC compared to 60% FC treatment. Soil moisture levels did not affected O2- concentration nor enzymatic activities. However, the treatment of 100%FC, significantly increased H2O2 concentration in stipules (p<0.1). Principal component analysis showed that H2O2 concentration was related to the weight of nodules, whereas number of nodules, aerial and root biomass were highly associated. Our results showed that soil moisture levels affected ROS balance of P. sativum plants associated to nodulation, and in turn it also affected plant growing variables. Future research will study the implications of ROS balance modifications on P. sativum plant nodulation. Pisum sativum, nodulation, ROS, antioxidant enzimatic activity
Caracterización fenotípica para tolerancia a salinidad de un panel de asociación de sorgo: Insumo clave para el análisis GWASLuna Dario Fernando (1)Bustos, D.A. (1); Ortiz, D. (2); Vieira de Sousa, L. (3); da Silva, R.R. (3), Pittaro, M.G. (1)(1) Instituto de Fisiología y Recursos Genéticos Vegetales, INTA-CIAP, Argentina. (2), Estación Exprimental Agropecuaria, INTA Manfredi, Universidade Federal Rural do Semi-arido, UFERSA.El mejoramiento genético del sorgo para la tolerancia a la salinidad ha quedado rezagado con respecto a la tolerancia a otros tipos de estrés; posiblemente, debido a que la tolerancia a la salinidad es un rasgo complejo tanto fisiológica como genéticamente. Una opción valida para abordar este tipo de estudios es el mapeo por asociación de genoma completo (GWAS).

El objetivo del presente trabajo fue caracterizar fenotípicamente un panel de asociación de 325 genotipos de sorgo (Sorghum Association Panel, SAP), que abarca en gran medida la variabilidad genotípica natural de esta especie. Se llevaron a cabo 4 ensayos en invernadero, utilizando un sistema de hidroponia con irrigación automática. Para la condición control se utilizó solución nutritiva completa Hoagland 0.5X; para el tratamiento salino, se utilizó la misma solución, más el agregado de 150 mM de NaCl. El tratamiento de salinidad se impuso cuando las plantas desarrollaron completamente su segunda hoja. Una vez alcanzado el desarrollo de la cuarta hoja, se midieron variables fisiológicas (temperatura foliar, contenido de clorofilas y su florescencia), y de crecimiento (peso, altura y espesor de hojas).

La salinidad afectó significativamente el crecimiento: peso seco de planta (39%), altura (29%) y espesor de hoja (27%) en los 325 genotipos de sorgo. Además, la salinidad afectó algunas variables fisiológicas como índice SPAD, el cual se redujo un 5%, el flujo lineal de electrones (LEF, disminuyó un %7), rendimiento cuántico del fotosistema II (jPS2, se redujo 9%), proporción de luz entrante que es perdido a través de procesos no regulados (jNO, aumentó un 17%), proporción de luz que va hacia el apagado no fotoquímico (jNPQ, incrementó 47%).

Los resultados de este fenotipado servirán de base para la localización de nuevos marcadores moleculares (SNPs) y la identificación de genes candidatos responsables de la tolerancia al estrés por salinidad mediante análisis GWAS.
sorgo, salinidad, fenotipado, GWAS
The transcription factor SCL28 controls the mitotic cell cycle, endoreplication and cell expansion and differentiation in Arabidopsis thalianaLòpez Alsina Maria MercedesVirginia Barrera1, Mercedes Lopez1, Camila Goldy1, Rodrigo Vena1, Ramiro E. Rodriguez1,2.1 IBR (Instituto de Biología Molecular y Celular de Rosario), CONICET and Universidad Nacional de Rosario, 2000 Rosario, Argentina. 2 Centro de Estudios Interdisciplinarios, Universidad Nacional de Rosario, 2000 Rosario, Argentina.Plant organ growth is a complex process involving production of new cells in meristems through the mitotic cell cycle (MCC) followed by anisotropic cell expansion. In plants, when cells exit the MCC, they usually engage in an alternative cell cycle known as endoreplication (ER), which involves DNA replication without subsequent mitosis. Regulation at the transcriptional level plays a predominant role in modulating the progression through the phases of the MCC, MCC exit, ER onset, and, finally, cell expansion. 


We have previously determined that Arabidopsis thaliana SCL28, a GRAS transcription factor (TF), is regulated by MYBR3 TFs in meristems through the binding to MSA motifs in the promoter. Functional analysis indicated that SCL28 promotes progression through the G2/M phases of the MCC and control the selection of cell division planes (Goldy et al. (2021) PNAS). Here, we further characterize the role of SCL28 in plant development exploring the downstream regulatory networks. 


To understand the SCL28 downstream regulatory network, we conducted transcriptome analyses of SCL28 mutants and SCL28 estradiol-inducible lines (XVE-SCL28). In this way, we identified direct and indirect targets of regulation by the transcription factor. These experiments revealed that SCL28 regulated genes include loci coding for cyclin-dependent kinase inhibitors from the SIAMESE-RELATED family that are involved in MCC exit and ER onset. Also, we identified genes related to cell wall and cytoskeleton, suggesting a direct role of SCL28 in cell expansion. Overall, our findings provide important insights into the regulation of plant organ growth and highlight the importance of the SCL28 regulatory network in this process.
"FLAVONOIDS: A SUSTAINABLE ALTERNATIVE FOR PLANT DISEASE CONTROL AND THEIR INTERACTION WITH PLANT GROWTH-PROMOTING MICROORGANISMS"Verónica VallejoSerra P. (1), Villafañe D. (2), Rodríguez, E. (2), Casati, P. (1)(1) Centro de Estudios Fotosintéticos y Bioquímicos (CONICET-UNR). (2) Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR).Plant beneficial rhizospheric microorganisms have the ability to colonize the rhizosphere and enhance plant growth, development, and nutrient use efficiency through a diverse array of mechanisms. The symbiotic interactions between plant roots and associated microorganisms play a fundamental role in the overall growth and development of plants. Roots actively secrete various metabolites, including flavonoids, which serve crucial roles in physiological processes, growth, development, and stress responses. Moreover, these flavonoids have the capacity to influence the composition of the microbiome associated with the roots, thereby impacting plant growth and defense mechanisms.

The primary objective of this study was to investigate the biological function of flavonoids during an infection with Pseudomonas syringae. We simultaneously studied how plants interacted with two beneficial microorganisms, Streptomyces ssp. and Trichoderma. The infection was conducted using both Arabidopsis thaliana wild type (Col-0 ecotype) and mutant plants deficient in the flavonoid biosynthetic pathway (tt4, tt5 and fls). In addition, the s3h mutant, which is a mutant in the salicylic 3-hydroxylase enzyme, was included, showing increased resistance to pathogen attacks. Treatment with Streptomyces and Trichoderma positively influenced the growth and development of both wild type and mutant plants, leading to increased seed production per plant and higher yields in greenhouse conditions. Notably, wild type plants exhibited heightened resistance against P. syringae infection. Surprisingly, the mutant plants displayed resistance to the pathogen, irrespective of the treatment with beneficial microorganisms.

In conclusion, our results provide evidence that flavonoids could potentially serve as effective control agents against phytopathogens. Furthermore, they play a crucial role in mediating the interactions between plants and beneficial microorganisms, promoting growth and development.
Epitranscriptomic marks in the root nodule symbiosisCueva Morales Marianela CarmenCarla Roda (1) Blanco Flavio (1) Zanetti Maria Eugenia (1)(1) IBBM (CONICET-UNLP)Regulation of gene expression takes place at multiple levels within eukaryotic cells, including chromatin-based, transcriptional, and post-transcriptional events. Dynamic RNA modifications, known as epitranscriptomic marks, have emerged as a new mechanism for post-transcriptional control of gene expression. The methylation of adenosines (m6A) is the most abundant modification found in RNA and its presence impacts on splicing, transport, localization, translation, and decay of RNAs. This mark is recognized by RNA binding proteins called ‘readers’ (ECT proteins) that drive these processes. In a previous study, we found transcripts differentially associated with the translational machinery at the early stages of the symbiotic relation between Medicago truncatula and Sinorhizobium meliloti. Considering that m6A of RNA is essential for  cell division and differentiation, and that this cellular mark affects the fate of transcrips, we attempt to elucidate the influence and function of m6A on the translatability of mRNAs during the formation of nitrogen-fixing nodules and development of lateral roots. We are using methylated RNA immunoprecipitation sequencing (meRIP) to investigate changes in m6A during root nodule symbiosis and lateral root formation to correlate these changes with variations in mRNA translation.  In silico analysis of the M. truncatula ECT family  showed that MtECT2/4, MtECT3 and MtECT11 are differentially expressed during the root nodule symbiosis and/or lateral root formation. Knock-down of MTECT11 alters infection by rhizobia, MtECT2/4 alters the progression of infection, whereas knock-down of MtECT2/4 alters the distribution and length of laterals root. FA-CLIP assays will be performed to identify the methylated transcripts recognized by these proteins.epitrancriptomic, plant physiology, symbiosis, lateral root formation
Leaf area at anthesis as conditioning of wheat baking qualityMiguel Mac ManeyMac Maney, M. (1); Benech-Arnold, L. (1); Fritz, N.E. (2); Miralles, D.M. (1, 3); Abeledo, L.G. (1, 3)(1) Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina. (2) Cámara Arbitral de Cereales de Bahía Blanca, Bahía Blanca, prov. de Buenos Aires, Argentina. (3) CONICET – IFEVA, Buenos Aires, ArgentinaThe relevance of the species as a crop is determined by the quality of the harvested product, but the physiology of cereal grain quality has not received as much attention as grain yield (GY). One of the variables that defines baking quality is grain nitrogen concentration (GNC). The objective of this work was to examine the ecophysiological mechanisms that underlie the interrelationship between grain yield and grain quality in bread wheat (Triticum aestivum L.). A field experiment was conducted at the School of Agronomy UBA combining 6 wheat cultivars, with contrasting baking aptitude, with 2 soil N availabilities (60 and 240 kg/ha) in a completely randomized design with 3 replications. Measurements related to carbon physiology (above-ground biomass at anthesis and at maturity, and its partition between organs), N physiology (N concentration in tissues, chlorophyll concentration and SPAD in flag leaf at anthesis) and baking quality parameters (gluten dry, alveogram) were taken. GY varied between 306 and 658 g/m2, while GNC varied between 1.6 and 2.7 %, with no relationship between both variables (p>0.10). The chlorophyll concentration in the flag leaf at anthesis showed a significant relationship with the SPAD measurements (r=0.92 p<0.001), which was a predictor of GY (r=0.79 p<0.01, for all the cultivars) and GNC (r=0.71 p<0.05 –with the exception of Prometeo–). High values of leaf area dry weight (r=0.72 p<0.01) and leaf area index (r=0.69 p<0.05) from the tillers at anthesis were also variables that described changes in GNC. GNC explained the variations in dry gluten (r=0.97 p<0.001) and in the alveographic parameters of dough strength (W; r=0.71 p<0.01), extensibility (L; r=0.84 p <0.001), and P/L ratio (r=-0.66 p<0.05). In conclusion, the N economy of the crop at anthesis (related to leaf area composition) conditioned the GNC at maturity, which determined the baking aptitude of the grains, with the cultivar acting as determining of the response.anthesis, chlorophyll, grain quality, protein, Triticum aestivum L.
Deciphering flavonoid production in Flaveria bidentis (L.) Kunze: Ecophysiological insights and implications for cultivation practicesDavidenco VaninaAgnese A. M. (1) , Giovanini A. (2,3)(1) Universidad Nacional de Córdoba (UNC), Facultad de Ciencias Químicas, Departamento de Ciencias Farmacéuticas (IMBIV-CONICET). (2) Becario EVC del CIN. (3) UNC, Facultad de Ciencias Agropecuarias (FCA), Cátedra de Fisiología Vegetal.In agronomic terms, Flaveria bidentis (L.) Kunze is a weed but holds significant interest for the pharmaceutical industry due to its ability to biosynthesize highly sulfated flavonoids (quercetin tetrasulfate and quercetin acetyl trisulfate) with proven antithrombotic activity. This study aimed to contribute eco-physiological insights to optimize its quantitative (biomass) and qualitative (flavonoids) performance through cultivation practices. Two field trials, E1 (2019-2020) and E2 (2020-2021), were conducted at FCA-UNC. E1 analyzed two sowing dates' impact on crop development, while E2 studied plant density (14p/m2; 7p/m2) and initial water availability (HW-350mm; LW-120 mm) effects on biomass generation and yield of polysulfated flavonoids. A split-plot design with 4 replications was used. The species exhibited a short-day response, flowering with a photoperiod of 12h 11m regardless of the sowing date. During reproductive stages, stems accounted for most aerial biomass, and a significant positive correlation was found between stem caliber and biomass. Initial water availability significantly affected biomass, resulting in a 35% decrease in LW compared to HW. All treatments reached the critical leaf area index, with LW taking 20 days longer than HW. Linear regression between aerial biomass and intercepted photosynthetically active radiation produced distinct models for each water condition. The radiation use efficiency decreased by 45% under LW. Qualitatively, preliminary studies made by paper chromatography showed that flavonoid concentration increased during reproductive stages, and they were predominantly concentrated in leaves. Water availability favored their production and plant density showed no significant effect. Additionally, apical plant portions produced significantly more flavonoids than basal ones. More studies relative to management practices are necessary to decipher physiological aspects related to F. bidentis cultivation and flavonoid production.3,7,3’,4’-quercetin tetrasulfate, crop management, yield
Yield and quality of buckwheat (Fagopyrum esculentum Moench) at different sowing dates and nitrogen fertility conditions.Sandra Amira AntequeraGuglielmini, A.C.; Alvarez Prado, S.; Rocca, C.M; Miralles, D.J.Facultad de Agronomía, Universidad de Buenos AiresBuckwheat is widely cultivated throughout the world due to its high nutritional value and its suitability for celiac diets, as it is gluten-free. Argentina has excellent agroecological conditions for its expansion; however, ecophysiological and agronomic knowledge is scarce both locally and globally.
This study aimed to develop ecophysiological bases to optimize the agronomic management of buckwheat and to determine its adaptability in different environments. It focused on predicting its phenological stages to adjust the crop cycle and optimize yield and quality according to environmental conditions.
Two field experiments were conducted at FAUBA, with different sowing dates from October to February and nitrogen (N) fertilization levels. Phenology, radiation interception, aerial biomass, yield and grain quality were analyzed.
It was found that the total length of the crop cycle was reduced by delaying sowing at a rate of 60 ºCd/day, with the grain filling stage being the most sensitive to shortening. Yields were higher at earlier sowing dates, associated mainly with changes in the number of grains set per m2. Nitrogen availability did not affect phenology or yield at the different dates explored.
Total aerial biomass decreased, and harvest index increased with delayed sowing. No relationship was found between harvest index and nitrogen levels.
Protein content increased with N availability from 50 to 75 kgN/ha, saturating the response from this value.
In conclusion, the study demonstrated the importance of adjusting the sowing date to optimize buckwheat yield in different environments, highlighting the relevant role of the length of grain filling in the duration of the crop cycle. Nitrogen availability did not affect phenology or yield but modified grain protein content. These findings could encourage the expansion of the crop in Argentina, considering its nutritional value and its potential in agricultural rotation schemes.
phenology, yield, grain quality
Autophagy modulates sugar cell efflux from leaves in ArabidopsisDana martinezGómez, I. (1); Hajirezaei, M-R. (2); Guiamet, J.J (1)(1)Instituto de Fisiología Vegetal (INFIVE)- UNLP CONICET, La Plata, Argentina. (2) Leibniz INSTITUTE OF PLANT GENETICS AND CROP PLANT RESEARCH (IPK), AlemaniaSugars serve as energy and as signaling molecules, affecting plant developmental processes such as source-sink relationships, growth, and senescence. Plants with impaired autophagy are hypersensitive to carbon starvation, displaying early senescence and growth arrest.  Autophagic mechanisms might be involved in the cellular partitioning of sugars.

Here we performed a GC-MS/MS based comparative analysis of intra- and extracellular pools of sucrose, glucose, and fructose in leaves of Arabidopsis, wild-type (WT) and autophagy knockout (atg5.ko) genotypes, grown in soil under 12h light-12h dark photoperiod. We quantified pools of sugars in mature leaves attached to or detached from the plant at the end of the light period and kept in the dark overnight or for 72 hrs. Also, phloem exudates (PE) were obtained from attached leaves. All the samples were collected after the end of the night period. Leaf apoplastic fluid (AF) was obtained by infiltration-centrifugation, and then the leaves were ground in liquid N and used as the intracellular fraction. At least 40 leaves were used per treatment.

WT leaves had higher sugar content and a lower ratio of Suc/hexoses in intra- and extracellular sugar pools than atg5.ko in all the conditions, indicating that autophagy contributes to intracellular sugar accumulation and down-regulates the outflow of sugars to the apoplast. This was even more noticeable when sugar export was impaired, in overnight detached leaves. After 72hs in darkness, leaves showed signs of senescence (chlorophyll and protein loss), more advanced in atg5.ko. Leaf sugar content and extra/intracellular ratio decreased in both genotypes, but this cellular partition declined less in atg5.ko. PE from atg5.ko had a markedly higher concentration of sugars (per leaf fresh weight) than that of WT.

Together, these results suggest that autophagy modulates sugar efflux from mature and senescing leaves.
Senescence, autophagy, sucrose, apoplast, cell efflux, sugar partitioning
Cytochrome c levels affect the TOR pathway to regulate growth and metabolism under energy-deficient conditionsCanal María Victoria (1)Mansilla, N. (1); Gras, D. E. (1); Ibarra, A. (1); Figueroa, C. M. (1); Gonzalez, D. H. (1); Welchen, E. (1)(1) Instituto de Agrobiotecnología del Litoral, Santa Fe, Argentina.Mitochondrial respiration is essential for energy production in most living organisms. Cytochrome c (CYTc) is a soluble heme protein of the mitochondrial intermembrane space, delivering electrons to complex IV during the last step of aerobic cellular respiration. We previously reported that Arabidopsis thaliana plants with lower CYTc levels (cytc mutants) exhibit decreased biomass and alterations in carbohydrate metabolism, explained partly by differential regulation in gibberellin (GA) homeostasis. In this work, we used mutant plants in the CYTc-1 gene. We found that cytc-1 mutants exhibit shorter roots than WT plants, and sugars do not rescue that difference. Moreover, cytc-1 mutants show decreased mitochondrial membrane potential and lower ATP content, even when carbon sources are present. They also exhibit higher free amino acid content, induced autophagy, and increased resistance to nutritional stress caused by prolonged darkness, similar to plants with triggered starvation signals. Several of those phenotypes are similar when the TOR pathway is affected. In that sense, we found that cytc-1 mutant seedlings have reduced S6K and RPS6 phosphorylation levels, indicating that the TOR pathway is reduced. Cytc-1 mutants also exhibit lower S6K protein levels due to increased protein degradation through the proteasome and autophagy. TOR overexpression in cytc-1 mutant background restores growth, autophagy, and the level of amino acids except for mitochondrial membrane potential and ATP levels, which remain low. We propose that CYTc-deficient plants coordinate their metabolism and energy availability by reducing TOR pathway activation as a preventive alarm signal to adjust growth in anticipation of running out of energy and affecting essential cellular processes, thus providing a mechanism by which changes in mitochondrial activity are transduced to the rest of the cell.Cytochrome c, mitochondria, ribosomal S6 kinase, autophagy, development
Resistance response of soybean genotypes to Asian Soybean Rust under controlled temperature conditionsCambursano, Mariana VirginiaCairo, C.A.; Bianchi, J.S.; Gomez, R.L. and Quijano, A.Laboratorio de Eco-Fisiología Vegetal (LEFIVE). Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET), Facultad de Ciencias Agrarias, UNR. Parque Villarino S/N, (S2125ZAA) Zavalla, Santa Fe, Argentina.The temperature increase (T) due to climate change has significant implications for crops, and is likely to be partially associated with more severe diseases. Asian Soybean Rust (ASR), caused by the fungal Phakopsora pachyrhyzi (Pp), is a highly destructive disease with phytosanitary risks for soybean in Argentina.  Even though ASR resistance genes has been identified, their effectiveness depends on the Pp isolates. In addition, the effect of T on the resistance responses remains poorly understood. Accurate characterization of disease traits under controlled environmental conditions is critical for germplasm selection in plant breeding programs. We studied the effect of different temperatures on soybean-Pp pathosystem using resistant and susceptible genotypes exposed to the BP08 Pp isolate under controlled environmental conditions. Resistance traits as Number of Uredinia per Lesion (N°UL), Percentage of Open Uredinia (%OU) and Sporulation Level (SL) were evaluated in 30 lesions of 12 soybean genotypes grown in contrasting mean temperatures (21.6°C and 26.6°C, for low-T and high-T, respectively). Two plants per genotype were inoculated at the 2nd and 3rd fully expanded trifoliate leaves by spraying 2.7 x 105 spores/mL of the BP08 Pp isolate. The phenotypic characterization was done 14 days post-inoculation, and means were compared by t-test. Higher temperature increased SL, N°UL and %OU in a 46, 36 and 32%, respectively (p≤0.10). Significant differences were also found in the resistance traits evaluated in many of the genotypes analyzed (p≤0.10). These preliminary findings suggest that an increase in temperature due to climate change could lead to an increase in ASR severity determining the importance of considering this effect in the manage of the soybean rust caused by Pp.climate change, temperature, Asian Soybean Rust
Auxin test induces parthenogenesis and aposporous-like embryo sacs in Paspalum notatumJuan Pablo A. OrtizVega, M.S (1); Siena, L.A. (1), Vega, J.M. (1), Pessino, S.C. (1), Leblanc, O. (2)(1) Instituto de Investigaciones en Ciencias Agrarias de Rosario, CONICET-Universidad Nacional de Rosario, S2125ZAA, Zavalla, Argentina. (2) DIADE, Université de Montpellier, IRD, CIRAD, 34394, Montpellier, France.Auxin plays an essential role in plant development. The 'auxin test' (the spraying of immature inflorescences with a dilute auxin solution) is used in some grass species to identify individuals with parthenogenesis. P. notatum is a subtropical fodder grass that forms a multiploid complex. The common form (2n=4x=40) reproduces by pseudogamous aposporous apomixis and is self-fertile. Apomixis involves the formation of unreduced aposporous embryo sacs (AES), the development of maternal embryos by parthenogenesis, and the formation of endosperm after fertilisation of polar nuclei. In AES parthenogenesis often begins before anthesis. Fully sexual tetraploid plants have never been found in nature, but can be produced artificially by colchicine treatment of diploids. The aim of this study was to evaluate the effect of the auxin test on the reproductive development of apomictic and sexual plants. Inflorescences were sprayed with an aqueous solution of 2,4-D (80mg/l + Tween 20) 10 to 3 days before anthesis. Inflorescences treated with distilled water served as controls. The experiments were carried out during the flowering seasons of the years 2021 and 2022. The effect of auxin was assessed by observation of ovules at anthesis. Auxin-treated inflorescences of apomictic plants showed a significant increase in the proportion of ovules with parthenogenetic embryos compared to controls (average 24% vs 11%, p=0.03 year 2021 and 23% vs 8%, p=0.02 year 2022). Proembryos, were also detected in meiotic embryo sacs (up to 14%). In sexual plants, auxin application resulted in an average of 7 and 12% of ovules bearing aposporous-like embryo sacs compared to 0% of controls, and up to 4% of ovules with double meiotic embryo sacs. No parthenogenetic embryos were observed. Our results indicate that external auxin application significantly increases the proportion of parthenogenetic embryos in apomictic genotypes and induces the formation of aposporous-like embryo sacs in sexual genotypes.apomixis, apospory, auxin, reproductive development, parthenogenesis, Paspalum notatum
Regulation of floral development in Arabidopsis thaliana by microRNAs.Franco Ezequiel LazzaraBeltramino, M. (1); Ferela, A. (1); Palatnik, J.F. (1)(1) Instituto de Biología Molecular y Celular de Rosario, Rosario, Santa Fe, Argentina.The growth of plant organs is tightly controlled by multiple genes and regulatory pathways. The GROWTH-REGULATING FACTOR (GRF) family is composed of nine members and seven of them are regulated by microRNA miR396. The miR396-GRF module has been found conserved in angiosperms and gymnosperms. GRFs acts as growth promoters, and plants with higher activity of GRFs have larger leaves and present a delay in senescence. ARF2 belongs to the AUXIN RESPONSE FAMILY of transcription factors. ARF2 is, in turn, regulated by trans-acting (ta-siRNA) small RNAs. The arf2 loss-of-function mutants have an increase in the size of the leaves and seeds, and a delay in senescence. Although previous works have already characterized how these systems regulate foliar and root growth, as well as others vegetative organs, little is known about how these systems interact in the floral and reproductive development of plants.
In this work, we evaluated the participation of the miR396/GRF and ta-siRNA/ARF2 in the control of flower development. We tested the role of the two systems by working with mutants and transgenic plants with modified levels of miR396, GRF and ARF2. We conducted a phenotypic analysis of these lines and we evaluated the expression levels of the different genes under study through RT-qPCR assays and reporter genes. Additionally, we searched for candidate genes that GRFs could be regulating to control the development of these organs, and we validated interactions using ChIP-qPCR assays. Based on the results obtained, we present a model of how these two systems define floral structures and, consequently, reproductive development in Arabidopsis.
plant physiology, molecular biology, GRF, flower development
DNA methylation regulates thermoresponsive growth in Arabidopsis by modulating CRY1 expressionMatias CapellaGarro, M. (1); Capella, M. (1)(1) Instituto de Agrobiotecnología del Litoral (UNL-CONICET), Colectora Ruta Nacional 168 km 0, S3000, Santa Fe, ArgentinaPlants adapt to warm environments through physiological and morphological changes termed thermomorphogenesis, which involve transcriptional reprogramming exerted mainly by PHYTOCHROME INTERACTING FACTOR 4 (PIF4). Fluctuating temperatures can also influence the patterns of cytosine DNA methylation, and thus gene expression. However, whether these epigenetic changes provide an adaptative advantage remains unclear. Here, we provide evidence that DNA methylation is required to regulate thermomorphogenesis. Hypomethylated drm1 drm2 cmt3 mutant seedlings show impaired hypocotyl elongation at mildly elevated temperatures. In agreement, blocking DNA methylation with the reagent 5-azacytidine impairs hypocotyl elongation in response to warming in three different Arabidopsis accessions, independently of SUPPRESSOR OF DRM1 DRM2 CMT3 expression. Additionally, treatment with 5-azacytidine decreased the expression of the auxin response reporter DR5::GUS during warming. At the molecular level, the lack of DNA methylation abolished the warming-mediated induction of PIF4 target genes, while up-regulation of PIF4 expression remained unchanged. Finally, DNA methylation impairs blue light inhibition of hypocotyl growth during thermomorphogenesis by repressing the expression of the blue-light receptor CRY1. Together, our findings provide evidence of the epigenetic regulation of a photoreceptor to control plant responses to warm environments.DNA methylation, thermomorphogenesis, hypocotyl elongation, warming
HOP co-chaperones contribute to GA signaling by stabilizing F-box protein SNE in Arabidopsis thalianaSilvina Mangano 1,2Alfonso Muñoz1 and M. Mar Castellano11 Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), Campus Montegancedo UPM (28223), Pozuelo de Alarcón (Madrid), Spain. 2 Instituto Tecnológico de Chascomús (CONICET-UNSAM), Av. Intendente Marino Km. 8,2 (B7130IWA), Chascomús (Buenos Aires), Argentina.Gibberellins (GAs) are phytohormones that control diverse aspects of plant growth and development, including seed germination, stem elongation, leaf expansion, flowering time, and reproduction. The GA transduction pathway involves a short signaling cascade that leads to the degradation of the DELLA transcriptional regulators. indeed, five DELLA proteins have been characterized in Arabidopsis: repressor of ga1-3 (RGA), GA-insensitive (GAI), and the RGA-like proteins 1–3 (RGL1, RGL2, and RGL3). These proteins show a differential expression pattern, which gives them a predominant role in different tissues and developmental transitions. Furthermore, two Arabidopsis F-box proteins are involved in DELLA degradation: SLY1 (SLEEPY) and SNE (SNEEZY). Nevertheless, the relevance of the stability of SLY1 and SNE, remains unknown. Here, we take advantage of mutants in the HSP70-HSP90 organizing protein (HOP) co-chaperones and reveal that these proteins contribute to the accumulation of SNE in Arabidopsis. Indeed, HOP proteins, along with HSP90 and HSP70, interact in vivo with SNE, and SNE accumulation is significantly reduced in the hop mutants. Concomitantly, greater accumulation of the DELLA protein RGA is observed in these plants. In agreement with these molecular phenotypes, hop mutants show a hypersensitive response to the GA inhibitor paclobutrazol and display a partial response to the ectopic addition of GA when GA-regulated processes are assayed. These mutants also display different phenotypes associated with alterations in the GA pathway, such as reduced germination rate, delayed bolting, and reduced hypocotyl elongation in response to warm temperatures. Remarkably, ectopic overexpression of SNE reverts the delay in germination and the thermally dependent hypocotyl elongation defect of the hop mutant, revealing that SNE accumulation is the key aspect of the hop mutant phenotypes. Together, these data reveal a pivotal role for HOP in SNE accumulation and GA signaling.HSP70-HSP90 organizing protein (HOP), seed germination, thermomorphogenesis, RGA, protein folding, protein stability.
CYP77A7 is essential for cell wall integrity during polar growth in ArabidopsisCascallares, María MilagrosPagnussat, GabrielaInstituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, CONICET, Mar del Plata, ArgentinaIn plants, cytochromes P450 (CYPs) catalyze a variety of monooxygenation/hydroxylation reactions involved in the biosynthesis and degradation of a plethora of compounds implicated in diverse physiological responses, including growth and development. In this study, we explore the function of CYP77A7, a cytochrome P450 that belongs to the CYP77 family, with several members identified as putative fatty acid oxidases. An in-silico co-expression analysis indicated that CYP77A7 co-expresses with genes related with synthesis and modification of the cell wall. Using transcriptional fusions with GFP we determined the expression pattern of CYP77A7, which showed high expression in pollen tubes, root hairs and thricomes, all structures characterized by polar growth. We analyzed two homozygous mutant alleles with insertions in CYP77A7 and observed that these plants exhibit aberrant root hair and pollen tubes growth. The anomalies detected included bifurcated growth, swollen tips, and wavy shanks. Also, by using specific probes and monoclonal antibodies to detect different components of the cell wall, we detected abnormal patterns of cell wall deposition in mutant root hairs. Overall, these results support the idea that cytochrome CYP77A7 plays an important role in the organization of the cell wall during polar growth whose bases are currently under study.Arabidopsis; polar growth; root hairs; cell wall; development
Yield and physical quality determinants of Flint maize in production lots.Micaela Seguí (1)Gerde, J.A. (1); Espejo, J. (2); Gambín, B. (1,3), Borrás, L. (1,4)(1)Facultad de Cs. Agrarias, UNR/CONICET, Zavalla, Argentina. (2)Dacsa Group, Rosario, Argentina. (3)Dirección actual: Iowa State University, Ames, Iowa, EEUU. (4)Dirección actual: Corteva Agrisience, Johnston, Iowa, EEUU.Non-GM Flint maize is grown exclusively in Argentina and most of it is exported to the EU as part of a highly traceable supply chain. All farms in this supply chain are required to follow strict traceability protocols, which include accurate recording of the GPS location and management variables used.
The use of specific genotypes is the basis of this supply chain. These hard endosperm genotypes have grain yields 10-20% lower than softer endosperm genotypes. As a result, the hard endosperm maize supply chain pays premiums to farmers for meeting certain quality parameters. These parameters are: (I) a test weight of 76 kg/hl; (II) a flotation index of 25% or less; and (III) vitreoussness of 92% or more.
Based on previous work, we hypothesise that genotype selection is the management decision that most influences quality traits, while both quality and physical yields are affected by environmental and management variables that affect the water balance. Supply chain traceability provides access to data on environmental variables that affect both yield and physical quality. A mixed modelling approach will be used for the statistical analysis to identify all the predictors that optimize hard endosperm maize production and allow recommendations to be made for each specific production region.
We collected data from all field lots of Flint maize destined for the EU in the 2021/2022 season and we complemented our database with field trials in all the production region. The average yield was 7847 kg ha-1 for all lots and trials. Of all the production lots, only 42% of them met the requirements to be considered as Flint maize. If a desirable screen retention of 50% is added to the physical quality traits, only 25% of the production lots are in compliance with the requirements. In most cases, the requirements weren't met because vitreousness was less than 92%. A first description of the hard endosperm maize supply chain is provided by these initial measurements.
Flint maize, dry milling, maize ecophysiology
Brassica rapa L. and Rapistrum rugosum L.: species of remedial capacity in saline soils contaminated with effluents with high environmental impactMaría Laura FiasconaroAbrile, M. (1); Osorio, J. (1); Orecchia, D. (1); Lovato, M.E. (1)(1) INTEC-CONICET, Universidad Nacional del Litoral, Ruta Nacional N° 168 Km 0, Santa Fe, 3000, ArgentinaBiosolids derived from the treatment of leaching from sanitary landfills represent a significant environmental and management problem in these complexes. On the other hand, they contain nutrients and organic matter (OM) that could be useful as improvers of cover soils in the landfill itself, frequently low in OM. However, they can also contain significant amounts of pollutants such as heavy metals and, due to their composition, generate salinity in the soils where they are applied.

Objetive of our study was to evaluate the remediation capacity of Brassica rapa L. and Rapistrum rugosum L. in a soil contaminated with sludge from a sanitary landfill and with a high salt content.

The selected plant species were grown in pots and under greenhouse conditions. These species are spontaneous growth in the area. Before transplanting, both the commercial soil used and the sludge were characterized. For the development of the plants, two doses of mud were applied, 10% and 20% to the soil. The plants were harvested during the flowering stage. After harvest, specific determinations were made that indicate the physiological state of the studied plants: photosynthetic pigments, sugars and total proteins in leaves, and activity of antioxidant enzymes, such as catalase (CAT) and guaiac peroxidase (GPX). Likewise, we proceeded to collect data on fresh weights and subsequent dry weight of the harvested plants.

The results obtained suggest that both species have remediation capacity and adaptation to saline soils contaminated with sludge. In B. rapa, growth (total dry weight) did not show differences between control plants and those grown in soil with mud; but in R. rugosum the mud provided the necessary nutrients for an increase in the dry mass of the plants. On the other hand, both species it was possible to observe that the sludge causes oxidative stress that is reflected in the increase in the activities of the antioxidant enzymes studied.
salinity, phytorremediation, wild plants, abiotic stress.
Evaluation of two contrasting sunflower inbred genotypes for leaf senescence trait under two different nitrogen suppliesCorzo MelanieCorzo, M. 1* ,Trupkin, S. 2, Becheran, D. 3 , Ploschuk, E. 3, Alvarez, D. 4, Heinz, N. 4 and Fernandez, P. 1(1)Instituto de biotecnologia, INTA Castelar, Argentina, 29 Instituto de floricultura, INTA Castelar, Argentina 2 IFEVA; FAUBA, Argentina 3 INTA EEA Manfredi, ArgentinaLeaf senescence is a complex mechanism controlled by multiple genetic and environmental variables. This last stage of leaf development is characterized by a decline in photosynthetic activity. Leaf senescence has an economic impact since it can affect the yield due to the opportunity of the plants to maintain the active photosynthetic system during prolonged periods, especially during the stage of filling of grains affecting the weight and oil content of the plant. The main objective of this work is to study leaf senescence processes in sunflower responding to different nitrogen supplies using a broad overview approach of integration with “omics”, physiological and phenotypical variable profiles. The field assay of two differential inbred lines previously selected from Sunflower INTA Breeding Program were analyzed through different leaf developmental stages in plants grown under different nitrogen supply at INTA Castelar.The results from this project will contribute to elucidate the pathways involved in the differential triggering and progression of the senescence process in sunflower and its stability under different N nutrition profiles, allowing the detection of biomarkers useful for genetic improvement of this edible oil crop of great importance for Argentine production. 

We are thankful to PDI084 for economical support for this meeting´s attendance. 

Characterization of 4-coumarate-CoA ligase family in potato (Solanum tuberosum L.)Valiñas MatíasLanteri, L.; ten Have, A.; Andreu, A.Instituto de Investigaciones Biológicas-CONICET-Universidad Nacional de Mar del Plata, Argentina4-coumarate-CoA ligase (4CL) enzymes belong to the acyl-CoA synthetase protein superfamily. In some plant species, specific class I and class II 4CL isoforms control the biosynthesis of lignin/ suberin and flavonoids, respectively. In order to study the 4CL family in Solanum tuberosum an in depth phylogenetic analysis was done. Using clustering techniques, functional annotation and taxonomic signals, three major clades were depicted. Clade 1 is composed of class I from monocotyledons, class I from dicotyledons and class II canonical 4CL enzymes subclades. The potato 4CL family comprises four class I (St4CL-I(A-D)) and one class II (St4CL-II) members. In order to determine the role of potato 4CLs, transcripts levels of St4CLs and of marker genes of the flavonoid (chalcone synthase, CHS) and suberin (feruloyl-CoA transferase, FHT) pathways were determined by qRT-PCR in flesh and skin of tubers from S. tuberosum spp. andigena varieties. St4CL-IA was barely detected in the skin of some varieties whereas St4CL-IB did not show a clear pattern. St4CL-IC and St4CL-ID could not be detected. St4CL-II expression pattern was similar to CHS. St4CL-IA and St4CL-IB were induced by wounding as did FHT, whereas St4CL-II and CHS expression was repressed. Constitutive and wound-induced expression suggests that St4CL-IA and St4CL-IB isoforms are likely involved in soluble and/ or suberin-bound phenolic compounds biosynthesis while St4CL-II appears to be involved in flavonoid biosynthesis.

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4-coumarate-CoA ligase, potato tuber, suberin, flavonoids
Effect of abscisic acid foliar applications on phytochemical content and antioxidant capacity of purple and orange carrotsMariano Tomás MauricciMalovini, E. (3); Valerga, L. (1,2); Cavagnaro, P.F. (1,2,4)(1) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); (2) Instituto Nacional de Tecnología Agropecuaria (INTA) EEA Mendoza, Luján de Cuyo, Mendoza, Argentina; (3) Cátedra de Fisiología Vegetal, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Mendoza, Argentina; (4) Instituto de Horticultura, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Mendoza, Argentina

Abscisic acid (ABA) plays a central role in regulating various physiological processes that help the plant survive and adapt to stressful conditions. In a number of species, exogenous foliar applications of ABA increased the total content of anthocyanins and phenolics in the applied organs, generally fruits and leaves. The objective of this study was to evaluate the effect of foliar applications of ABA on four carrot varieties: Black Nebula (BN); Purple Elite (PE), Cosmic Purple (CPP), and Shin Kuroda (SK). Weekly foliar ABA applications were initiated 60 days after sowing and until harvest, using five different concentrations: 0 (control), 10, 50, 100, and 200 ppm. When the roots reached commercial size they were harvested. Total anthocyanins (TA), total phenolics (TP), and antioxidant capacity (AC) levels were determined using the differential pH, Folin-Ciocalteu, and FRAP procedures, respectively. A significant genotype-related response was found (p<0.05). In BN roots, average increases of 89%, 58%, and 50% were observed for TA, TP, and AC, respectively, relative to ABA-untreated controls, with maximum increases found at concentrations of 50-200 ppm. In PE, significant increases in the range of 53-73% were found using 100-200 ppm of ABA, whereas no significant increases in TP and AC were found for this variety at all the concentrations tested. No significant changes were found for these variables in the remaining purple (CPP) and orange (SK) varieties due to ABA at all the doses evaluated. These data suggest that the response to ABA depends on the carrot genotype, the phytochemical analyzed, and the ABA doses applied. Ongoing gene expression analysis in ABA-treated versus untreated samples may reveal candidate genes associated with the response to exogenous applications of this plant hormone mediated by the phenylpropanoid pathway. Altogether, our results suggest that exogenous ABA applications may be used to increase the functional value of some purple carrots.

Carrot, abiotic stress, abscisic acid, polyphenols, anthocyanins, antioxidant capacity.
Abscisic acid and ABI4 appears to be involved in Arabidopsis thaliana gamma carbonic anhydrases regulation during embryogenesisValiñas MatíasMarchetti, F.; Pagnussat, G.; Zabaleta, E.Instituto de Investigaciones Biológicas-CONICET-Universidad Nacional de Mar del PlataAbscisic acid (ABA) is a hormone involved in many plant’s processes, among which seed development and germination. ABA signaling pathway requires the action of ABSCISIC ACID INSENSITIVE (ABI) transcription factors. In particular, ABI4 has been shown to regulate the expression of cytochrome c 2, a member of the mitochondrial electron transport chain (mETC), during germination in Arabidopsis. However, it is unknown if this and other members of mETC are regulated by ABA during embryogenesis. Arabidopsis thaliana gamma carbonic anhydrases (AtɣCA) form a heterotrimeric domain (CA1-CA2-CAL2, named CA domain) that is part of the mitochondrial Complex I and it is essential for its assembly. Transcript levels of some AtɣCA family members increase during the maturation phase of embryo development and reach a peak at the end, as do ABA levels, whereas other members show an opposite trend, according to RNAseq publicly available data. In addition, in silico analysis of the promoter regions of AtɣCAs show putative binding sites for ABI transcription factors. In order to determine whether ABA regulates AtɣCA expression by ABI4, their transcript levels were determined by RT-qPCR in immature seeds of Arabidopsis WT and abi4 mutant plants treated with ABA. Preliminary results indicate that ABA induces AtɣCA2, while it represses AtɣCA1 expression in WT plants. On the contrary, AtɣCA1 levels are increased in abi4 mutants whereas AtɣCA2 are reduced. Taken together, results suggest that ABA is involved in AtɣCA regulation through ABI4 during embryogenesis. This differential regulation may have an impact on the composition of the CA domain affecting complex I function. Future experiments will be directed to study GUS activity in pCA::GUS reporter plants in response to ABA treatment.

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abscisic acid, carbonic anhydrases, embryogenesis
Contributions of symbiosis with native rhizobacteria to salt stress tolerance in Neltuma flexuosaMesquida Nardini María ClaraMelchiorre, M. (1); Lescano López, I. (1); Palomeque, J. (1)(1) Unidad de Estudios Agropecuarios (UDEA, CONICET-INTA)Argentina ranks third globally in terms of land surface affected by salinity. The presence of native woody species tolerant to salinity as well as their associated rhizobacteria can be an alternative for the restoration of degraded soils. In particular, the genus Neltuma includes valuable forest and food species of algarrobo, that associate with rhizobia capable of atmospheric nitrogen fixation. The objective of this study is to evaluate the contributions of the symbiotic interaction between N. flexuosa and native rhizobacteria to salinity tolerance. In previous studies, two rhizobia isolates were selected from two salt flats in Argentina, "Pipanaco" in Catamarca and "La Antigua" in La Rioja, as they showed tolerance to salinity stress during free-living growth. In the laboratory, we observed that these isolates grow in liquid nutrient medium at concentrations of 300 mM NaCl similary to the control, although the isolate from Pipanaco showed higher tolerance to these conditions. On the other hand, N. flexuosa presented a general reduction in its growth when subjected to a concentration of 250 mM NaCl. These conditions were used to evaluate the contributions of inoculation with rhizobacteria from salt flats on the growth and stress response of N. flexuosa. Variables such as growth and development, as well as the ureide content were analyzed under the studied conditions.Neltuma flexuosa, rhizobia, salinity stress, nitrogen fixation
Role of the jasmonic acid pathway in UV-B-mediated responses in ArabidopsisMedina-Fraga Ana LauraCrocco, C.D. (1); Ballaré, C.L. (2)Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, IFEVA, UBA, ArgentinaUV-B radiation induces anti-herbivore defenses in Arabidopsis: one step closer to the molecular mechanism

Defense responses against herbivores and necrotrophic pathogens in plants are principally mediated by the jasmonic acid (JA) pathway. The expression of this pathway is repressed by JAZ repressor proteins, which prevent MYC transcription factors from activating the transcription of defense-related genes. Previous studies have shown that solar UV-B radiation can enhance plant defenses against herbivores, but the mechanisms are not fully understood (reviewed in Ballaré 2014). In this study, we tested the role of the JA pathway in mediating the effects of UV-B radiation on the resistance of Arabidopsis plants to Spodoptera frugiperda caterpillars.

Insects grown on plants previously exposed to UV-B radiation accumulated less mass in “no-choice” bioassays compared to insects reared on plants not treated. This reduced insect growth correlated with increased accumulation of bioactive jasmonates and expression of JA response marker genes in plants exposed to UV-B. The effect of UV-B radiation enhancing plant resistance to S. frugiperda was not present in an aos null mutant, which is impaired in a critical step of JA biosynthesis. Moreover, plants exposed to low doses of UV-B radiation in the growth chamber or to natural doses of solar UV-B radiation in the field showed decreased stability of the JAZ10 repressor protein. Furthermore, in preliminary studies we found that the UV-B increased the abundance of transcription factors of the MYC family.

Taken together, our results suggest that, in this system, UV-B radiation enhances plant resistance to insect herbivory by decreasing the stability of JAZ repressor proteins, presumably as a consequence of increased accumulation of bioactive jasmonates.

Ballaré CL. Light regulation of plant defense. Annu Rev Plant Biol. 2014;65:335-63. doi: 10.1146/annurev-arplant-050213-040145. Epub 2014 Jan 23. PMID: 24471835.
Defense response, light response, jasmonic, plant physiology
Unravelling maternal effects in Arabidopsis thaliana seeds: from controlled environments to the wildAilén AuthierAuge, G.A. (1)(1) Instituto de Agrobiotecnología y Biología Molecular, INTA, Argentina.Plants have a remarkable capacity to perceive and respond to environmental changes experienced in their life cycles and those of previous generations. Particularly, transgenerational plasticity provides the progeny with valuable information to respond with optimal phenotypes in diverse environmental conditions. The intricate interplay between immediate environmental cues and transgenerational effects plays a pivotal role in shaping germination responses, particularly in heterogeneous environments, where phenotypic plasticity becomes a noteworthy characteristic. The primary focus of this study was to assess the expression of maternal effects in progeny seeds from 10 Arabidopsis thaliana ecotypes exposed to two distinct environmental conditions: controlled (indoor) and heterogenous (outdoor) environments. We grew a first generation of plants (G1) under two treatments: vernalization, where 2-week-old seedlings were either exposed four weeks at 4°C (12h/12h day/night), and non-vernalization, where plants completed their life cycle at 23°C (16h/8h day/night). Freshly harvested seeds were used for germination assays in controlled conditions (23°C, 16h/8h day/night), or simultaneously sown in a field experimental plot to record seedling emergence per day. The field experiments were conducted in two consecutive years: in 2022 in FCEN (Ciudad Universitaria, CABA) and in 2023 in INTA (Hurlingham, AMBA). Our results show that seeds express maternal effects in both conditions (indoor and outdoor) and that this response of the progeny was also influenced by the ecotype (significant maternal environment x ecotype interaction). Additionally, ecotypes matched their responses in controlled and heterogenous conditions, indicating that maternal effects might be adaptive. These results offer valuable insights into the germination response of the progeny and shed light on the role of transgenerational effects, unravelling a fascinating aspect of plant life and adaptation.Arabidopsis thaliana, maternal effects, germination, experimental field, ecotype.
Flowering responses of young olive trees (Olea europaea) to experimental warming during summer and autumn in Northwest ArgentinaMiserere, A. (1)Searles, P.S. (1); Federico, A.A. (2); Herrera, C.J. (1); Brizuela, M.M. (1); Rousseaux, M.C. (1)(1) Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-Provincia de La Rioja-UNLaR- SEGEMAR-UNCa-CONICET), Argentina. (2) Facultad de Agronomía, Universidad de Buenos Aires, Argentina.Olive expansion into new growing areas and global warming require a better understanding of the effects of elevated temperature on flowering. This study aimed to assess how warming during summer and autumn affects the timing of flowering and its intensity in two olive cultivars. A field, warming experiment was conducted in La Rioja, using two-year-old, potted olive trees (‘Arbequina’, ‘Coratina’). Two temperature levels, a near-ambient control (T0) and an actively-heated (T+) treatment (+3°C), were established from December to mid-May of the 2014-15 growing season in open-top chambers (OTCs). The treatments were applied during the entire period, early (Dec-Feb), or late (Feb to mid-May). Additional trees located in an adjacent nursery received no temperature manipulation (NM). In spring, the full bloom date (FB, at least 50% of flowers open) and the flowering intensity (FI; % of lateral buds with inflorescences) were determined visually with weekly observations. The FB date was affected by the treatment period, but not by the temperature level. In ‘Arbequina’, entire and late trees had later FB dates (4-6 days) than NM and early trees. In ‘Coratina’, trees from the early, late, and entire periods flowered 2-3 days later than NM trees. The FI in ‘Arbequina’ was greater than 60% in NM and T0 trees from all treatment periods. T+ trees from the early period also had high FI. However, FI was significantly reduced to 10% in trees warmed during the entire or late periods. In ‘Coratina’, the FI was high in the NM and early trees, but FI was very low in both T0 and T+ trees from the entire or late periods. The results indicate that warm air temperatures during autumn will likely reduce FI substantially with climate change, even in cultivars with relatively low chilling requirements such as ‘Arbequina’ and ‘Coratina’. Thus, limiting olive production in Northwest Argentina unless more suitable cultivars can be found.global warming, open top chamber, flowering intensity, flowering date, Arbequina, Coratina
Exploring the Role of Autophagy in Defense Priming and Systemic Resistance in ArabidopsisRobert GLacase L (1,3), Cambiagno D (1), Cecchini N (2), Lascano R (1,3), Robert G (1,3,4)(1) Stress Biology Group, Unidad de Estudios Agropecuarios (UDEA), INTA-CONICET. (2) Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), UNC-CONICET. (3) Laboratorio y Cátedra de Fisiología Vegetal, FCEFyN-UNC. (4) Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV), CIAP-INTACellular memory in plants is regulated by epigenetic and non-epigenetic mechanisms, including the turnover of proteins. After pathogen attack, plants establish broad-spectrum immunity relying on programs that control systemic resistance and immunological memory or priming. Autophagy, a degradation process controlling protein and organelle quality, plays a role in plant immune responses; however, its involvement in defense priming and systemic resistance remains underexplored. In this study, using publicly databases, we assessed the expression of autophagy-related genes (Atg) in Arabidopsis 24 h after applying priming inducers, namely pipecolic acid (Pip) and hydroxy-Pip. The expression level of several Atg genes was significantly modulated. We further explored autophagy regulation during defense priming by treating autophagy-reporter transgenic plants with 1 mM Pip or water (as a control) for 1 h, evaluating autophagic flux 24 h later. No significant differences in autophagic activity were observed between the treatments. We also examined the systemic resistance against Pseudomonas syringae pv. maculicola (Psm) induced by Pip in autophagy-defective mutants. Pip treatment induced systemic resistance to Psm and inhibited primary root growth, though less pronounced than in wildtype plants. As autophagy-defective mutants display a defense-related phenotype that depends on leaf age, likely due to the developmentally controlled increase of SA and reactive oxygen species levels, we are currently analyzing systemic resistance responses and defense priming at various developmental leaf stages. In this regard, preliminary results indicated that Pip treatment, which did not affect the cellular redox state, conferred increased redox capacity to a subsequent oxidative stress, depending on the leaf developmental stage in Arabidopsis.Plant physiology, defense, priming, autophagy
AUTOPHAGY MODULATION IN LEGUME-RHIZOBIA INTERACTIONS: UNRAVELING LOCAL AND SYSTEMIC RESPONSES IN COMPATIBLE AND INCOMPATIBLE CONTEXTSMusso ManuelMusso M (1,2), Bellis P (1), Lascano R (1,2), Robert G (1,2,3)(1) Stress Biology Group, Unidad de Estudios Agropecuarios (UDEA), INTA-CONICET. (2) Laboratorio y Cátedra de Fisiología Vegetal, FCEFyN-UNC. (3) Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV), CIAP-INTAThe legume-rhizobia symbiotic interaction, both compatible and incompatible (the former leading to the formation of new organs, nodules, where biological nitrogen fixation occurs), is regulated at local and systemic levels and involves mechanisms related to plant immunity. Our research revealed that autophagy, a conserved degrative process, contributes to the establishment of the compatible interaction between Glycine max and Bradyrhizobium diazzoeficiens (USDA110). Using hairy roots with post-transcriptional gene silencing via RNAi, we demonstrated that downregulation of GmAtg4, as well as components of the autophagy- and vesicle trafficking-related PI3K complex (GmPI3K and GmAtg6), hindered the modulation of defense responses in roots and impaired nodule formation. Interestingly, molecular responses associated with the perception of rhizobia nodulation factors were induced in Atg4-RNAi hairy roots after inoculation, but were abolished in both PI3K-related genotypes (PI3K- and Atg6-RNAi hairy roots). This indicated that PI3K, but also Atg6, fulfills other biological functions beyond autophagy, potentially linked to specific roles of PI3KCI and PI3KCII complexes in plants. In order to investigate autophagy modulation in both compatible and incompatible interactions, we inoculated Glycine max cvs L76-1988 (Rj2 rfg1) seedlings with the rhizobium USDA 110 (compatible) and USDA 122 (incompatible). At 2 and 5 days post-inoculation, we analyzed the expression levels of autophagy-related genes (Atg), immunity response markers genes, molecular components related to systemic signaling, and symbiosis marker genes in both local (roots) and systemic (the first trifoliate leaves) context. Our findings suggest a crucial role of fine-tuning autophagy during symbiotic interactions, contributing to the modulation of defense programs within the symbiotic context.Plant physiology, symbiosis, defense, autophagy
MACROAUTOPHAGY AND MICROAUTOPHAGY IN ARABIDOPSIS: EFFECTS ON TONOPLAST CONTENT AND VACUOLAR MORPHOLOGYSilva BrunoSilva B (1,2), Bellis P (1), Lascano R (1,2), Robert G (1,2,3)(1) Stress Biology Group, Unidad de Estudios Agropecuarios (UDEA), INTA-CONICET. (2) Laboratorio y Cátedra de Fisiología Vegetal, FCEFyN-UNC. (3) Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV), CIAP-INTADifferent endomembrane trafficking pathways, such as endocytosis and autophagy, terminate in the vacuole. While the impact of vesicular trafficking on tonoplast content and vacuole growth has been addressed, the specific contribution of autophagy remains poorly explored. In plants, two main forms of autophagy are macroautophagy (MacroA) and microautophagy (MicroA). MacroA involves the transport of double-membrane vesicles (autophagosomes) to the vacuole, whereas through MicroA, cytoplasmic constituents are directly incorporated into the vacuolar lumen via morphological transformations of the tonoplast, leading to cargo and tonoplast portions degradation. In this study, we analyzed vacuole morphology and the kinetics (4, 16, and 24h) of MacroA activation in response to classical inducers of this process, such as nitrogen and carbon deficiency. Additionally, we evaluated tonoplast-localized protein degradation (GFP-SYP22) as an approach to monitor MicroA in plants. Our results show faster MacroA activation in response to darkness treatments (4-16h) compared to nitrogen deficiency (16-24h). Furthermore, significant degradation of the GFP-SYP22 protein was evident at later time points of darkness treatment compared to control and nitrogen-deficient conditions, likely as a mechanism to provide carbon to survive this starvation. The analysis of estimated tonoplast content in epidermal leaf cells through the tonoplast perimeter/vacuolar area ratio showed an increase after 4h of darkness but decreased in subsequent times compared to plants subjected to control conditions. In contrast, under nitrogen deficiency treatments, there was an increase in tonoplast quantity after 24 h of treatment compared to control. These results indicate a certain correlation between tonoplast content and the rates of MacroA and MicroA activation. Currently, we are evaluating changes in vacuolar dynamics and tonoplast content in autophagy-deficient mutant plants.cell biology, macroautophagy, microautophagy, vacuole, tonoplast content
A vertically transmitted fungal symbiont prevents the drought-induced intergenerational inhibition of seed germinationFrank Zarraga BarcoUeno, A.C. (1,2); Casabella, M.P. (3); Casas, C. (2,3); Molina-Montenegro, M. (1,4); Ramos, P. (5,6); Schnyder, H. (7) & Gundel, P.E. (1,2)(1) Centro de Ecología Integrativa, Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile. (2) IFEVA, CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina. (3) Facultad de Agronomía, Departamento de Recursos Naturales y Ambiente, Universidad de Buenos Aires, Cátedra de Edafología, Buenos Aires, Argentina. (4) Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad Católica del Norte, Coquimbo, Chile. (5) Instituto de Ciencias Biológicas, Universidad de Talca, Talca, Chile. (6) Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile. (7) Lehrstuhl für Grünlandlehre, Technische Universität München, Freising-Weihenstephan, Germany.Under the current global warming crisis, water deficit is predicted to increase and limit plant fitness. In response to water deficit, plants activate hormone signaling pathways that allow them to adjust their phenotypes by mechanisms like the synthesis and accumulation of metabolites with osmotic and antioxidant properties. Additionally, plants associate symbiotically with microorganisms that increase plant tolerance to water deficit. Although some microorganisms are maternally inherited, it is unknown how they modulate the intergenerational effect of the water deficit on early stages of progeny. Here, we investigated the effect of a vertically transmitted fungal endophyte on the consequences of maternal drought on seed germination water requirements. We explored whether these effects were mediated by the accumulation of specialized metabolites with osmotic properties in seeds. Independently on the symbiosis, water deficit impaired seed production of parental plants. The presence of endophyte induced the accumulation of specialized (e.g., mannitol and sorbitol) and reserve molecules (e.g., starch) in seeds with and without maternal water deficit history. Interestingly, seeds that were produced under drought showed higher level of dormancy than seeds produced under control condition only if they were free of endophytes. This latter effect was not observed in seeds produced by endophyte-symbiotic plants. The results suggest that the accumulation of metabolites in seeds is a consequence of how endophyte-symbiotic plants perceive and - respond to - the drought rather than a mechanism that can improve seed performance in eventual scenarios of water deficit. Our study shows that vertically transmitted fungal endophytes differentially modulate the environmental factor-induced maternal effects in plants.drought, symbiosis, intergenerational effect, Epichloë
Effect of water stress in Megathyrsus maximus during vegetative growth and early selection of promising genotypesArias Claudia VaninaCarrizo, I. M. (1, 2); Arias, C. V. (3); Grunberg, K. (1,4); Hernández U. M. (1); López Colomba, E. (1,2,3)(1) Unidad de Estudios Agropecuarios (UDEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto Nacional de Tecnología Agropecuaria (INTA), Córdoba, Argentina; (2) Facultad de Ciencias Agropecuarias, Universidad Católica de Córdoba, Argentina; (3) Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Argentina; (4) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).Megathyrsus maximus is a cultivated forage grass in tropical and subtropical regions of the world. In Argentina it is widely used in livestock systems due to its high production and forage quality. However, climatic restrictions, such as the scarcity of rainfall, cause yield losses in this species. The aim of this work was to characterize M. maximus genotypes under water stress conditions in early stages of growth through the measurement of physiological, biochemical, and morpho-agronomic parameters. Eight M. maximus genotypes (Green Panic (GR), Gatton Panic (GA), Mutale (MU), Vencedor (VE), Penquero (PE), 55PE, 73MU and 16GR) were evaluated in two soil water contents (SWC), control (80% SWC) and water stress (20% SWC, during 25 days). Significant differences were observed for the evaluated characters after 72 h of exposure to stress. GA presented the highest value of relative water content (RWC) without differences with its control, followed by GR. On the other hand, PE, 16GR and 55PE registered the greatest difference (˃30%). Regarding the maximum quantum efficiency of fluorescence (Fv/Fm), GR under stress conditions registered the highest value (0.78) without differences with its control, while VE and PE registered the lowest value (0.63 and 0 .64, respectively). All genotypes under stress conditions increased their malondialdehyde content (MDA), with the smallest differences compared with the respective control plants observed in 73MU (21%),GA (23%) and GR (34%). In contrast, PE, 16GR and VE differed by 208%, 149% and 131%, respectively. At the end of the assay, GR and GA registered the least reduction in aerial dry weight and height, while VE and MU were the most affected genotypes. GR and GA could be selected as stress tolerant genotypes, being VE and PE the most susceptible genotypes. In conclusion, it was possible to identify through early selection tools promising genotypes for tolerance to water stress in M. maximus that could be used in breeding programs.Panicum maximum, drought stress, early growth stages, selection tools
Next generation potatoes obtained through gene editingGabriela Massa (1, 2)Décima Oneto, C.A. (1, 2); González, M.N. (1); Poulsen Hornum, A. (2,3); Arizmendi, A. (1); Feingold, S.E. (1)(1) Laboratorio de Agrobiotecnología, IPADS Balcarce (INTA - CONICET), Balcarce, Argentina. (2) Facultad de Ciencias Agrarias-UNMdP, Mar del Plata, Argentina. (3) Agencia Nacional de Promoción Científica y Tecnológica, Argentina.The potato is the third most consumed food crop in the world, following rice and wheat. In Argentina, modern cultivated potato production is mainly concentrated in Buenos Aires and Córdoba. Among the most used varieties are cv. Spunta for fresh consumption and cv. Atlantic for the potato chip industry. The main industrial characteristics to improve in cultivated potatoes are enzymatic browning and cold-induced sweetening (CIS), both of which lead to reduced quality in fresh produce and/or processed products. Regarding production-related traits, the objective is to obtain potatoes that utilize available water more efficiently. Due to the agamic and polyploid nature of potatoes, traditional breeding methods can take 15 years. Therefore, the use of new biotechnological techniques allows for shorter development times for new varieties. In our group, we utilize the CRISPR/Cas9 gene editing technique to obtain improved varieties with one or more of the aforementioned characteristics. The first development in our group was the bruise-resistant potato derived from cv. Desiree, by knock out (KO) the polyphenol oxidase gene (StPPO2), responsible for enzymatic browning. We performed the KO of the vacuolar invertase gene (StInvVac) from cv. Atlantic to obtain the potato resistant to CIS. To obtain potatoes that use the available water more efficiently, we performed KO of the CBP80 gene, a transcription factor involved in the ABA signaling pathway, in cv. Spunta. We are progressing in obtaining cv. Spunta potatoes with both StPPO2 and StInvVac genes edited simultaneously. The lines with CIS resistance and with improved available water use efficiency will be submitted to CONABIA for evaluation. In the current year, the bruise-resistant line will be registered as a new variety with INASE. Our results demonstrate that gene editing applications can generate superior quality products that provide benefits for both the production and industrial sectors, as well as consumers.
Characterization of Arabidopsis thaliana heat shock protein Hsp81.2 in the plant apoplastAgustín Atela (1)Patricia Uchiya (1), Leandro Solmi (2), Luisa F. Morales-Mendoza (1), Andrés V. Ramos-Duarte (1), Andrés Gárriz (2), Franco Rossi(2), Valeria Sander (1), Marina Clemente (1) Mariana G. Corigliano (1)(1) Laboratorio de Molecular Farming y Vacunas. INTECH, Argentina. (2) Unidad de Biotecnología 1. INTECH, ArgentinaThe results presented in this work were obtained in agreement with RIZOBACTER ARGENTINA S.A (CONVE-2022-120066190-APN-GVT_CONICET) .
Hsp90s are found in all plant cellular compartments examined to date, and Hsp90s have also been found in the apoplast. Even though their roles in this location remain elusive, we added some light to this issue by assessing the regulation of defense-associated mechanisms in Arabidopsis thaliana plants infiltrated with the recombinant Hsp90 protein (AtHsp81.2). In this trend, we previously showed that ROS production and callose deposition were incremented upon rAtHsp81.2 infiltration. Besides, a 24h pre-treatment of leaves with AtHsp81.2 resulted in a reduction in the proliferation of Pseudomonas syringae pv. tomato DC3000, whereas the in vitro growth of the bacteria is not affected in the presence of rAtHsp81.2 suggesting that this protein may participate in the induction of defense. In the present study, we attempted to gain a deeper insight into the role played by AtHsp90s by evaluating their effects on defense against PstDC3000. We assayed 1-, 2-, 3-, 4-, 5-, 6- y 7-days pre-treatment with 100 µg ml-1 of AtHsp81.2 and it resulted in a reduction in the proliferation of PstDC3000 compared with control group (only PstDC3000). We also assayed a spray-based protocol in order to explore whether AtHsp81.2 either at 100 or 500 µg ml-1 activate plant immune response, but the reduction in the proliferation of PstDC300 was observed just until 3-days pretreatment. Our results suggest that Hsp90s localized in the plant apoplast play an active role in the activation of the plant defense mechanisms against pathogens since it is important for mounting appropriate plant immune response and it is also long lasting.
Heat Shock protein, apoplast, plant defense, plant immune response
The alteration of chlorophyll metabolism affects the germination of tomato seedsSantoro Luciano JoséDe Luca, María Belén(1); Echeverría, Martin(1); Burgos, Estanislao(1); Conte, Mariana(2); Olivari, Florencia(2); Beracochea, Valeria(2); Bermúdez, Luisa(2); Asís, Ramón(3); Carrari, Fernando(1).(1)nstituto de fisiología, Biología Molecular y Neurociencias, (IFIBYNE). Ciudad universitaria, CABA, Buenos Aires, Argentina. (2)Instituto de Biotecnología, (IB-INTA) y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Castelar, Argentina.(3)CIBICI, Facultad de Ciencias Químicas Universidad Nacional de Córdoba, Argentina.Chlorophyll metabolism (biosynthesis, recycling and degradation) is a tightly regulated process which is essential for photosynthesis of higher plants and most of the related enzyme encoding genes were identified. In addition, one of the products of this pathway, phytyl diphosphate, is a key component in the synthesis of vitamins essentials for the human diet, such as tocopherols (Vitamin E). Phytyl di phosphate is generated from the phytol tail that is released from the chlorophyll ring. This compound undergoes two phosphorylations by two kinases encoded by the VTE5 (phytol kinase) and VTE6 (phytyl phosphate kinase) genes. In this work, tomato plants (Solanum lycopersicum Cv. Microtom) that overexpress orthologous genes from Arabidopsis thaliana AtVTE5 or AtVTE6 under a constitutive promoter were studied. In turn, single transgenic plants were crossed in order to obtain double overexpressing plants. Molecular and chemical studies were carried out in different plant organs such as leaves and fruits in different stages, as well as physiological studies in seeds and mature plants grown under standard conditions.

Chlorophyll metabolism; tocochromanols; phytol kinase (VTE5); phytyl phosphate kinase (VTE6); photosynthesis
Is cold acclimation the key to frost tolerant Eucalyptus in a warming world?Gustavo Pedro Javier Oberschelp.Estación Experimental Agropecuaria Concordia, INTA, Argentina.Trees have evolved a plethora of mechanisms to cope with multiple stresses to ensure survival and reproductive success. While annual plants can regulate their life cycle to fit optimal conditions, perennial plants have to regulate pathways to survive winters and regulate growth to sustain life cycle. This process has been fine-tuned over millions of years and is now under severe pressure from climate change. Trees have thrived over similar challenges many times before, but this time they are threatened by the speed and intensity of change. Moreover, crop plants and trees are closely linked to the economy and development of particular ecoregions, making crop and population migration a last resort. As the climate warms, extreme events could become more frequent, exacerbating the effects of climate change. Recent years have seen an increase in the occurrence and duration of cold spells and disruptive snowfalls around the world. Climate change is causing both an earlier start to the growing season and warmer frosts, but the former effect dominates the latter. Frost-tolerant Eucalyptus species are capable of withstanding cold stress by a process termed cold acclimation. It relies on sensing cold non freezing temperatures and converting them into an internal signal to trigger a defense mechanism through a transcriptional cascade to synthesize various protective biomolecules. Under climate change, this strategy is threatened. Therefore, to safeguard planted forest productivity, frost tolerance strategies need revamping. Fortunately, some Eucalyptus species under study can thrive in this scenario. Research on frost tolerance mechanisms and genes must continue to deliver them into new tolerant genotypes.Cold acclimation, Climate change, Abiotic stress, Plant physiology, Breeding
Floodwater depth effects on nitrogen and phosphorus partition in young willow plants during the post-stress period.Virginia M. C. LuquezIrina Mozo (1), Silvia Monteoliva(1), Virginia M. C. Luquez (1)(1) INFIVE (Instituto de Fisiología Vegetal) CC327 (1900) La Plata, Argentina.Flooding alters nutrient uptake by plants, but less is known about the effects once the stress period is over. The aim of this work was to analyze the effects of flooding depth on N and P partition in young willows plants during the post-stress recovery period.
We analyzed two commercial hybrid willow clones (Salix matsudana x S. alba): Agronales and Carapachay. Plants were grown in pots and experienced two flooding regimes: partial flooding (PF) and plants totally submerged in water (TS). Plants responses were analyzed after 21 days of flooding and at the end of a 28 days period of post-flooding recovery. After the flooding episode, N and P increased in the leaves of the PF treatment, but not in the TS treatment. Clone Agronales had a higher N and P foliar concentration than Carapachay. These differences persisted after the post -flooding recovery period. There were no differences in nutrient concentration in stems and roots of the PF treatment in any sampling date. Flooded plants in TS treatment increased both N and P in stems, but these differences did not persist after the 28 days recovery period. There were no differences in the amount of N and P in leaves and roots in the TS treatment.
Willows plants totally submerged adopted a typical quiescence strategy, suppressing growth, while the PF plants grew in height during the stress episode. Floodwater depth affected N and P partition, their concentration increased in leaves in PF but not in the TS treatment. The plants of the S treatment experienced a transient increase in stem nutrient concentration, that did not persist after the end of the stress episode. The higher concentration in stems of TS could be simple accumulation because N and P are not used for growth during flooding, and not a consequence of an enhanced uptake by the plants. But the changes in nutrient concentration in leaves are likely part of a persistent acclimation response.
submergence, partial flooding, post-flooding, Salix
Effects of conditioning and storage environment on dormancy release in malting barley grainsDominguez, C.P. (1,2)Benech-Arnold, R.L. (1,2); Rodriguez, M.V. (2,3)(1) Cátedra de Cultivos Industriales, FAUBA, Argentina. (2) IFEVA-CONICET-UBA, Argentina. (3) Cátedra de Fisiología Vegetal, FAUBA, Argentina.Barley grains must meet strict germination standards to be malted. Grain dormancy inhibits germination and interferes with the malting process. Dormant seed batches are allowed to after-ripen for variable periods until dormancy is released. The objective of this work was to evaluate how different storage conditions affect the dormancy release dynamics of malting barley grains. Experiments were performed with "Andreia", a popular cultivar used for malting in Argentina. Once harvested, threshed grains were divided into different batches, each one destined to reach a target moisture content (8.5; 10.5; 12.5 and 15.5%, dry weight basis) and then stored under different temperatures (ST= -18; 5; 10; 15; 20 and 25ºC), oxygen availability (21% oxygen and hypoxia, only for grains stored at 5 and 25ºC), and storage time (30; 77 and 126 days from harvest). At time "zero" (once the four target moisture content were achieved and before starting storage), a germination test was carried out under three contrasting incubation temperatures (10, 20 and 25ºC) to determine the level of dormancy presented by the grains of the different treatments. In the three storage times, germination tests were also carried out (with certain modifications in the incubation conditions) depending on the results that were obtained. At the beginning of storage, barley grains did not show differences in the level of dormancy after adjusting the target moisture content levels. Subsequently, in the three storage times, strong interactions of moisture content with storage temperature were evidenced. For grains with moisture content of 15.5% and warm temperatures (20-25ºC), the progress of deterioration became evident. The moisture content between 8.5 and 12.5% and its storage at 20-25ºC were the optimal conditions to promote the dormancy release in grains.barley, dormancy, germination, grains, moisture, oxygen, storage, temperature
Fluctuations in phloem transport of assimilates in response to mineral nutritionCarla CaputoVeliz C.V. (1): Criado M.V (1); Roberts I.N. (1). Prystupa P. (1); Ploschuk E. (2)(1) Instituto de Investigaciones en Biociencias Agrícolas y Ambientales (INBA). FAUBA/CONICET, Argentina (2) Cátedra de Cultivos Industriales, FAUBA, ArgentinaIn cereals, remobilization of assimilates (mainly sucrose and amino acids) from vegetative tissues is an important source of carbon (C) and nitrogen (N) for the developing grains. In the Argentinian Pampas (main barley growing area) N, phosphorus (P) and sulphur (S) are the nutrients that most commonly limit crop production. Several experiments were carried with or without N, P or S fertilization in barley plants in field or under controlled conditions (both in greenhouse and growth chamber) in order to analyze several key components involved in C and N assimilation and remobilization and their relation with grain protein content and composition. Phloem amino acids fluctuated in response to nutrient availability, increasing at the beginning of grain filling under N or P deficiency, decreasing all along the process under S deficiency, remaining constant in well provided plants and decaying at the end of the grain filling period in non-fertilized ones. The contribution of amino acids from the phloem was found to be of great importance for the protein content of the grain, while the contribution of sugars showed a potential role in regulating the expression of the B-hordein genes (most abundant grain proteins). In recent years, we have focused on the effects of S availability and we observed that S deficiency leads to a delay in the phyllochron, leaf expansion and senescence, as well as an inhibition of C and N assimilation and recycling by down-regulation of the diffusional, photochemical and metabolic processes involved in photosynthesis, together with a down regulation of glutamine synthetase and several sugar and amino acid transporter genes. Altogether, the results indicate that C and N remobilization to sink tissues are highly influenced by nutrient availability, with a particularly significant role of S for the nutrient delivery to sink tissues.plant nutrition, plant physiology, cereal production
Overexpression of ADC2 in Arabidopsis improves nitrogen use efficiency under nitrogen limitationMaria Patricia Benavides (1,2)Recalde, L. (1); Cabrera, A.V. (1); Rossi, F.R. (3,4); Groppa, M.D. (1,2)(1) Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires. (2) IQUIFIB-CONICET. (3) Instituto Tecnológico de Chascomús (CONICET-UNSAM). (4) Escuela de Bio y Nanotecnologías (UNSAM).For sustainable agriculture, improving nitrogen use efficiency (NUE) in plants is crucial to reduce environmental damage caused by excessive fertilizers application while still achieving high crop productivity. Polyamines Putrescine (Put), Spermidine (Spd), and Spermine (Spm) are vital for plant growth and development, as well as for stress tolerance. The aim of this study was to analyze whether the Arabidopsis transgenic line overexpressing ADC2 gene, which accumulates Put (line 7.2), exhibited an improved performance under N limitation compared to wild type plants (WT, Col-0). Plants were grown in aerated hydroponic culture for 21 days, in N-sufficient (N+) or N-deficient (N-) medium. Under N+, both lines showed similar growth. Under N limitation, both genotypes exhibited decreased rosette growth compared to N+. However, line 7.2 showed a larger rosette diameter and leaf size, and higher fresh and dry weight compared to WT. Under N-, line 7.2 developed a larger root system than WT, along with higher nitrate reductase activity and NO3- content; moreover nitrate transporter NRT1.1 gene showed a higher expression level in the transgenic line than in the WT.  Under N-, glutamine syntethase activity decreased in line 7.2 compared to N+, while it did not change in WT plants. Total chlorophyll and protein content remained unchanged between N- and N+ rosettes, while total soluble carbohydrates and total free amino acid content were slightly higher in N- than in N+ rosettes, for both genotypes. Antioxidant enzymes activity increased in both genotypes under N-, with line 7.2 showing higher activity levels than WT in both N+ and N- medium. While WT plants showed a decrease in Put, Spd and Spm content under N limitation, line 7.2 did not show any changes. This study demonstrated that Arabidopsis plants overexpressing ADC2 gene, displayed a better performance under N limitation compared to WT plants. Primary N metabolism was improved, resulting in higher NUE and growth.poliamines, nitrogen metabolism, nitrogen use efficiency
Understanding tolerance mechanisms of NO alleviating alkaline stress in tomatoSTEELHEART, Charlotte (1)Ganganelli, I. (1), Alegre, M. (1), Gergoff Grozeff G. (1), Bartoli, C.G. (1)(1) INFIVE, Facultades de Ciencias Agrarias y Forestales y Ciencias Naturales, Univ Nac de La Plata-CCT CONICET La Plata, ArgentinaTomato plants are sensitive to various abiotic stresses. Both alkaline and saline conditions influence photosynthesis and metabolism, and many studies show that tolerance is closely associated with the ability to maintain redox homeostasis. Previous works demonstrated the participation of exogenous nitric oxide (NO) increasing tolerance to alkaline stress. The present study was designed to determine the effect of exogenous NO in tomato seedlings to alleviate alkaline stress (sodium bicarbonate - NaHCO3) in roots and leaves. The experiments were conducted with tomato seedlings (Solanum lycopersicum L UCO14 de INTA), and the treatments included control treatment (Hoagland nutrient solution), alkalinity treatment (Hoagland nutrient solution plus 5 mM or 15 mM NaHCO3) and NO treatment (Hoagland nutritive solution plus 5 mM GSNO -S-nitroso glutathione, a NO donor- and 5 mM or 15 mM NaHCO3) which were performed for 10 days when all physiological indices were evaluated. Compared with the control, it was observed that tomato plants exposed to alkaline stress decreased height and fresh weight of shoot and roots and decreased photosynthesis and chlorophyll in leaves, while GSNO application to alkaline-stressed seedlings significantly improved these growth parameters. Different patterns in ROS production, antioxidant content, lipid peroxidation and organic acid content were observed between roots and leaves of seedlings during NO treatment under alkaline stress, suggesting a tissue-specific NO responses alleviating alkaline stress in tomato plants. Analysis of NADH/NAD+ content and the expression of genes encoding for the enzyme malate dehydrogenase isoforms and the expression of NAD+ transporter genes (NDT1/2 and PXN), in roots and leaves of tomato plants are in progress and will provide more information on the redox interaction of tomato plants under alkaline stress.

Finantial support: PICT 2019 - 2573 (ANPCyT) and A322, Universidad Nacional de La Plata

Tomato plants, nitric oxide, alkaline stress, redox homeostasis, plant physiology
INTEGRATION OF ENVIRONMENTAL SIGNALS VIA ROS-MAPKs THAT REGULATE POLAR GROWTH OF RADICAL HAIRS IN THALIANA ARABIDOPSIS AT LOW TEMPERATUREYossmayer RondonRondon, Y. (1); Martinez, J.(1); Núñez-Lillo, G. (3); Urzúa, T. (2); Meneses, C. (2) & Estevez, J. M. (1)(1) Fundacion Instituto Leloir. (2)2ANID - Millennium Science Initiative Program - Millennium Nucleus for the Development of Super Adaptable Plants (MN-SAP), Santiago, Chile. (3) 3Escuela de Agronomía, Facultad de Ciencias Agronómicas y de los Alimentos, Pontificia Universidad Católica de Valparaíso.
Root hairs are affected by intrinsic and extrinsic factors of the environment in which they are found, causing changes in their metabolism that directly affect their development. Low temperatures influence the growth of root hairs, causing alterations in redox metabolism through the production and accumulation of reactive oxygen species (ROS). In A. thaliana, some ROS, such as hydrogen peroxide (H2O2), can act as intracellular messengers, using specific channel proteins, such as PIPs-type aquaporins, being transported through the plasma membrane to the intracellular space, once there, H2O2 is capable of activating the mitogen-activated protein kinase (MAPK) signaling cascade, regulating the polar growth of root hairs by activating genes involved in the process. It was identified by RNA-seq analysis that under low temperature conditions (10ºC) there is a differential change in the expression patterns for mpks and pips in the rsl2/rsl4 mutant with respect to the WT (Col-0) at 2 and 6h after cold exposure, highlighting two groups: a group of genes that are activated, while the other set seems to decrease its expression in this period of time, pips and mpks genes belonging to these clusters were chosen as candidates to perform a quantitative analysis of root hair length. Measurements were made for simple and double T-DNA insertional mutants of pips and mpks under conditions of 22°C and 10°C, showing significant differences with respect to the wild-type phenotype at both temperatures, supporting was obtained in the RNA-seq expression profiles, indicating that these proteins have a possible regulatory role in root hair growth, especially at low temperatures. In addition, cytoplasmic ROS measurements were made using 2′,7′-Dichlorofluorescein diacetate and apoplastic H2O2 with Amplex Ultra Red for Col-0 and for pip mutants, observing a decrease in these values ​​at 10°C, suggesting that low temperature altered ROS transport and consequently the activation of MPKs cascades.
Arabidopsis, MAPKs, PIPs, low temperature, root hairs, ROS. 
Strategies to enhance foreign protein synthesis in the secretory pathway of plant cells.Petruccelli, SOcampo, C.G (1), Vignolles, F (1), Pombo, M.A (2)., Rosli H.G. (2), Petruccelli, S (1)(1) Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina, (2) Instituto de Fisiología Vegetal, INFIVE, Universidad Nacional de La Plata, CONICET, La Plata, ArgentinaMost proteins of commercial interest require modifications typical of secretory pathway to be produced in an active form. Different engineering strategies have been used in yeast and mammalian cells to enhance the synthesis, folding, and transport capacity in the secretory pathway, however, in plant cells, such approaches have not yet been tested. Developing seeds have a huge capacity for protein synthesis, so we hypothesized that a key regulator of seed development could increase the ability of leaves to produce proteins in the secretory pathway. By transient expression in Nicotiana benthamiana leaves, we show that the Arabidopsis Leafy Cotyledon 2 (AtLEC2) transcription factor augment accumulation of endoplasmic reticulum-targeted beta-glucuronidase, but not of its cytosolic variant. In addition, AtLEC2 increases yields of reporter proteins sorted to different compartments of the secretory pathway. To understand AtLEC2-induced changes, differentially expressed genes (DEGs) between leaves infiltrated with agrobacteria carrying AtLEC2 versus control empty agrobacteria were analyzed by RNAseq. AtLEC2 modified the expression of 835 transcripts (q<0.01), 574 up-regulated and 261 down-regulated. Gene Ontology analysis of the DEGs indicates that these genes participate in ribosome and chloroplast biogenesis, photosynthesis, translation, auxin metabolism, membrane synthesis, etc. Similar to yeast and mammalian transcription factors involved in the differentiation of professional secretory cells, AtLEC2-modified genes involved in translation and energy production.  By CLSM, we show that AtLEC2 induces secretion of vacuole-sorted proteins and increases the stability of apoplast-targeted proteins.  This the first report that shows the impact of a key regulator of seed development in secretory pathway protein synthesis. Our results contribute to the knowledge of plant secretory cell differentiation processes and to the development of novel genetic engineering strategies.Molecular Farming, plant secretory pathway, Arabidopsis Leafy Cotyledon 2, protein synthesis, transcriptome analysis
PIF4 enhances the expression of SAUR genes to promote growth in response to nitrateMatías Ezequiel PereyraMatías Ezequiel Pereyra (a, b), Cecilia Costigliolo Rojas (b), Anne F. Jarrell (d), Austin S. Hovland (c), Stephen A. Snipes (d), Punita Nagpal (d), David Alabadi (e), Miguel A. Blázquez (e), Rodrigo A.Gutiérrez (f), Jason W. Reed (d), William M. Gray (c), Jorge José Casal (a,b)(a) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, Facultad de Agronomía, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1417 Buenos Aires, Argentina. (b) Fundaciόn Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1405 Buenos Aires, Argentina. (c) Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, United States of America. (d) Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280. (e) Instituto de Biologίa Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, Universidad Politécnica de Valencia, 46022 Valencia, Spain. (f) Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, ChileNitrate supply is fundamental to support shoot growth and crop performance, but the associated increase in stem height exacerbates the risks of lodging and yield losses. Despite their significance for agriculture, the mechanisms involved in the promotion of stem growth by nitrate remain poorly understood. Here we show that the elongation of the hypocotyl of Arabidopsis thaliana, used as a model, responds rapidly and persistently to upshifts in nitrate concentration, rather than to the nitrate level itself. The response occurred even in shoots dissected from their roots and required NITRATE TRANSPORTER 1.1 (NRT1.1) in the phosphorylated state (but not NRT1.1 nitrate transport capacity) and NIN-LIKE PROTEIN 7 (NLP7). Nitrate increased PHYTOCHROME INTERACTING FACTOR 4 (PIF4) nuclear abundance by post-transcriptional mechanisms that depended on NRT1.1 and phytochrome B. In response to nitrate, PIF4 enhanced the expression of numerous SMALL AUXIN-UP RNA (SAUR) genes in the hypocotyl. The growth response to nitrate required PIF4, positive and negative regulators of its activity, including AUXIN RESPONSE FACTORs, and SAURs. PIF4 integrates cues from the soil (nitrate) and aerial (shade) environments adjusting plant stature to facilitate the access to light.NRT1.1 / NLP7 / ARF7 / shade
Characterization of potential TE-derived inverted repeat regulatory elements impacting gene expression and genome topologyCandela HourietMencia, R. (1); Arce, A. (1)(1) Instituto de Agrobiotecnología del LitoralPlant genomes are particularly rich in transposable elements (TEs), due to the mobile nature of these elements. Plants protect the integrity of their genomes by keeping TEs silenced through RNA-directed DNA methylation, a pathway in which small RNAs (siRNAs) are produced from TEs and they direct DNA methylation on them. The model plant Arabidopsis thaliana contains over 20% of TEs and other repetitive elements in its genome, but those numbers can reach up to 80% in some crops. Inverted repeats (IRs) are a type of TEs that have the particularity of being able to produce 24-nt siRNAs in a Polymerase II-dependent manner and induce DNA methylation. It has been recently shown that IRs can carry regulatory functions as they are able to alter chromatin conformation, resulting in gene expression changes. Here, we selected three Arabidopsis genes near IRs based on previous data obtained by NGS associated with chromatin changes, methylation, siRNAs and gene expression levels. The goal was to study the effects of the nearby IRs on the expression of the following genes: AT1G57630 (Toll-Interleukin-Resistance (TIR) domain family protein), AT4G19520 (Disease resistance protein (TIR-NBS-LRR class) family), AT2G40220 (ABI4, ABA insensitive 4). The former two genes are involved in the defense response, and the latter is a positive regulator in the phytohormone abscisic acid (ABA) signaling cascade, thus it is implicated in seed germination. Arabidopsis accessions containing polymorphisms in the IRs in their genomes and T-DNA mutants were obtained to perform different assays. We quantified their  transcript levels and compared accessions with and without the IRs. We also performed flowering and germination assays to establish differences in their development and growth, possibly associated with ABI4 responses. Our results indicate that the IRs may impact gene expression in these cases and thereby contribute to natural adaptations to environmental conditions.chromating conformation, inverted repeats, transcriptional regulation
Compatibility of endophytic bacteria with Mesorhizobium ciceri R26 in chickpea (Cicer arietinum)Sardo, Ma.FlorenciaRuiz,O. A. (2); Monteoliva, M. (3); Valetti, Lucio. (1)(1)IPAVE-CIAP-INTA, UFYMA. Córdoba, Argentina. (2)INTECH. Chascomús, Argentina. (3)IFRGV-CIAP-INTA, UDEA. Córdoba, Argentina. 

Worldwide one of the most limiting factors for chickpea productivity is the Ascochyta blight, a fungal disease caused by Ascochyta rabiei. In optimum conditions of humidity and temperature for fungal growth, Ascochyta can produce yield loss of 100%. Our group have beneficial bacteria with the capacity to control that disease. However, we do not know if they are compatible with biological nitrogen fixers (Mesorhizobium ciceri) usually inoculated to chickpea crops. This project aimed to assess the compatibility to produce functional nodules of M. ciceri R26 and biocontrol bacteria (called NKG-50, HFG-8, FH1 and FR2). Pot experiments were carried out with a completely randomized design (n=6). Sterile vermiculite inoculated with 1 ml of saturated culture of M. ciceri R26. Chickpea seeds were germinated in sterility and transplanted to the pots while inoculated with the bacteria suspension (1x109 ufc/ml). Once transplanted, seedlings were irrigated with 0.5X Hoagland solution (with or without N). After 30 days, plants were harvested. Nodules number, dry weight, and percentage of red nodules were evaluated, as well as chlorophyll content (as N indicator), and dry shoot and root biomass.
Combined inoculation with FH1 strain and M. ciceri showed significant increase in all nodule related parameters. Root biomass was increased by the combined inoculation of FH1 and FR2 plus M. ciceri, suggesting a growth promoter effect of these isolates. Overall, results suggest that biocontrol bacteria NKG-50, HFG-8, and FH1, isolated from healthy chickpea plants, are compatible with the biological nitrogen fixer M. ciceri R26.
Funds: INTA-PD-2019-I069, INTA-PD-2023-I071, INTA-PD-2023-I084, PICT SART UP 2018-0065
chickpea, Ascochyta rabiei, Mesorhizobium ciceri, biological nitrogen fixation
Juvenile-to-adult phase transition in grapevineDiego LijavetzkyLijavetzky, D. (1); Royo, C. (2); Ferradás, Y. (3); Martínez-Zapater, J.M. (2)(1) Instituto de Biología Agrícola de Mendoza (IBAM, CONICET-UNCuyo) Chacras de Coria, Mendoza, Argentina. (2) Instituto de Ciencias de la Vid y del Vino-ICVV (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Logroño, La Rioja, España. (3) Universidad de Santiago de Compostela, EspañaThe sequential activity of miR156 and miR172 on their targeted genes (i.e., SQUAMOSA PROMOTER BINDING PROTEIN-LIKE -SPL-), controls the juvenile to adult phase transition in several plants. A decrease in miR156 abundance and an increase in miR172 abundance are associated with the phase transition. Very little is known about phase transition in horticultural tree crops, which have a substantially long vegetative phase. In grapevine, phase transitions are dissociated, presenting a transition from juvenile to adult state in the first year and a subsequent induction of flowering in later years. Being a highly heterozygous species, generating a genetically homogeneous material for replicated transcriptomic analyses from seeds is not a trivial task. Here, we present a detailed global expression analysis of the main genes involved in the juvenile to adult phase transition during the development of the grapevine plant from seeds. RNA-seq analysis showed a clear repression of miR156 in the adult phase, marked in the grapevine by the appearance of tendrils. Consistent with what was observed in other annual plants, we observed the consequent activation of several SPL genes, known to be targets of miR156, and providing evidence for the conservation of the regulatory module miR156-SPLs in grapevine. No variation was detected in the expression of miR172, determining the floral induction, which is expected given that the grapevine does not flower during the first year. However, we were able to observe the over-expression of several genes involved in the floral meristem identity transition. This would be consistent with the common origin of tendrils and inflorescences, considered homologous organs. Our results indicate the conservation of the juvenile to adult phase transition mechanisms in grapevine and a differentiation with annual species given the absence of floral induction during the first year of development of the plant from seeds.miR156, miR172, miR156 targeted SPLs, phase transition, juvenility and adult, microRNA
Molecular farming as a biotechnological tool in the production of vaccine antigensMarina ClementeSánchez-López, E.; Ramos-Duarte, A.; Mendoza-Morales, L.; Sander, V.A.; Corigliano, M.G.Instituto Tecnológico Chascomús, INTECHThe search for more cost-effective and safer antigen production systems led to the exploration of plants as biofactories (PBPs, plant-based platforms) for recombinant molecule synthesis. After 30 years of development, PBPs have been consolidated in various well-characterized niches, with standardized processes and good production practices. In particular, the vaccine development for livestock production using PBP constitutes a strategic solution for the agro-industrial sector of developing countries. Our working group has evaluated different plant-based heterologous expression strategies to optimize their use in the production of vaccine antigens. The results obtained so far encourage us to propose the fusion of these antigens (non-vegetable proteins) to the 90-kDa heat shock proteins (Hsp90) from plants, in this case in their dual role as carrier and adjuvant, as a novel strategy to increase the expression level of recombinant proteins. Through this approach, we have obtained recombinant protein production yields that are competitive with those obtained by other conventional expression systems. Likewise, we standardized the purification conditions by affinity chromatography on Ni+2 resin. Our investigations suggest that this platform is a suitable and powerful biotechnological system for the expression of immunogenic antigens.
Unraveling the impact of high temperature on autophagy-linked plant immunityLescano López IgnacioMesquida Nardini, M.C. (1); Cecchini, N.M. (2); Lascano, R.H. (1)(1) Unidad de Estudios Agropecuarios (UDEA, CONICET-INTA). (2) Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, CONICET)Autophagy is a key regulatory process in plant immunity, contributing to both cell survival and cell death responses. Through this mechanism, cells degrade and recycle damaged or unwanted cellular components massively and selectively. The modulation of this pathway varies in response to diverse environmental factors. This study aims to understand how different temperature increments influence components of the autophagy pathway, thereby altering defense responses in plants. To investigate potential changes in autophagy under varying temperature conditions, we analyzed plants expressing the autophagy reporter GFP-ATG8a exposed to thermomorphogenesis (30°C) and heat stress (37°C and 45°C) temperatures using Western blot and confocal microscopy assays. We observed that the autophagic flux and levels of autophagy-related proteins varied with the intensity of the applied thermal shock. Remarkably, plants exposed to higher temperatures displayed increased susceptibility to Pseudomonas syringae pv. maculicola (Pma), with the most pronounced sensitivity observed at 45°C. Moreover, we noticed a synergistic effect between Pma infection and exposure to 30°C, which led to a boost in autophagic flux and the number of autophagic bodies. Notably, the heightened susceptibility to Pma observed in autophagy mutants strongly suggests that autophagy activation plays a critical role in modulating defense responses under thermomorphogenesis conditions. This study sheds light on the intricate interplay between autophagy and plant immunity across different temperature regimes, providing valuable insights into potential strategies for enhancing plant defense in response to thermal stress.temperature, heat stress, thermomorphogenesis, plant immunity, autophagy
Exploring early signaling events under phosphorus restriction in soybean plantsLuquet M (1)Antonelli, C. J. (1); Gergoff Grozeff, G. E (1); Buet, A. (2); Galatro, A. (1)1 Instituto de Fisiología Vegetal (INFIVE), CCT CONICET La Plata-Universidad Nacional de La Plata (UNLP), Diagonal 113 Nº 495 (1900), La Plata, Argentina. 2 Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue (CITAAC), CONICET - Universidad Nacional del Comahue, Buenos Aires 1400 (Q8300IBX) Neuquén, Argentina.It has been described that nitric oxide (NO) participates in some aspects of plant mineral nutrition influencing mechanisms underlying nutrient acquisition and utilization. In order to explore NO metabolism/signaling under P restriction in soybean plants, we evaluated changes in endogenous NO levels in the first hours of P restriction, focusing on possible pathways involved in its generation (such as nitrate reductase, NR; and nitric oxide synthase like, NOSlike). Soybean seedlings (Glycine max cv. Williams 82) were grown for 7 days under controlled conditions (28°C, 200 μmol m−2 s-1 of PAR, and 16-h photoperiod) in nutrient solution. Then, plants were separated into groups receiving the following treatments for four days: P deficiency (nutrient solution without phosphate addition, -P), P deficiency plus 100 μM sodium tungstate (an inhibitor of NR activity) or 100 μM L-NAME (a known inhibitor of mammalian NOS), and full nutrient solution (500 µM phosphate, +P) as control. NO levels were evaluated employing the DAF-FM-DA probe and fluorescence microscopy, being an increase in NO levels observed in -P leaves, but not in roots. The treatment of plants with L-NAME did not affect NO levels in leaves, while the inhibition of NR activity abolished DAF-FM fluorescence. In addition, hormone levels such as indole acetic acid (IAA), gibberellic acid (GA) and abscisic acid (ABA) were evaluated. Four days after P restriction no significant differences were observed in IAA levels neither in leaves nor in roots of P-starved plants, as compared to control; however, the content of GA3 significantly decreased in roots of -P plants. ABA levels were increased in -P roots as compared to control values. Interestingly, the treatment of -P plants with sodium tungstate did not restored ABA and GA levels to control values. Overall, the data presented here suggest a possible role for ABA, GA, and NO in signaling events during the first hours of P deprivation in soybean plants.Nitric oxide, phosphorus deficiency, soybean,phy
The water concentration of Acrocomia totai fruits as a predictor of the dynamics of fruit filling and oil accumulationEdmundo L. PloschukD.F. Wassner (1), H.D. Bertero (2, 3) y E.L. Ploschuk (1)Universidad de Buenos Aires, Facultad de Agronomía, (1) Cátedra de Cultivos Industriales, (2) Cátedra de Producción Vegetal y (3) IFEVA - CONICETAcrocomia totai (Araceae) is an Argentine palm that is being researched as a new oil crop. The fruits fall off when they are ripe (December to March), what could be avoided by harvesting them before ripening. To do so, it is required to understand the fruit filling dynamics and devise a simple method for determining the level of progress.    We assessed the fruit´s water concentration (WCF, %), as a predictor of fruit filling progress, and determined the WCF when each fruit component is defined: pericarp (PE), mesocarp (ME), endocarp (EN), and seed (SE), as well the oil accumulation in ME and SE. Fruits in 3 clusters of a plant in Buenos Aires were sampled monthly between 5/9/21 and 4/12/22.  At each harvest, 8 fruits per cluster were sampled and the fresh and dry weights of each component, as well as their oil content, were calculated. Fruits collected every 3 months from plants growing in Formosa, Corrientes, and Entre Rios were analysed to validate the model. Fruit physiological maturity was achieved at a WCF of 40%, whereas the WCF in dropped ripe fruits under natural condition was between 25 and 12%. Each fruit component displayed distinct filling dynamics. With 80% WCF, the PE began increasing its biomass, and with 42% WCF, it reached 80% of its dry weight (DW) and then raised with 40% WCF to its full DW. The ME achieved 60% of its DW with 50% WCF and then jumped to 100% with 40% WCF. The full DW of EN is determined early, at 60% WCF, whereas the SE begins with 65% and finishes with 40% WCF. Oil accumulation in ME began at 55% WCF and in SE at 65% WCF, with maximum levels at 40 and 50% WCF, respectively. In the SE, increases in dry weight and oil occurred simultaneously, whereas in the ME, oil accumulation began with the generation of 50% of its biomass. In conclusion, the WCF is a good parameter to assess the stage of fruit development under different environmental conditions, and it serves as a basis for the creation of a model for predicting fruit quality.Acrocomia, Fruit filling, Fruit quality
Wheat lines, suffering structural rearrangements between wheat-1BS and rye-1RS chromosomes, display differential patterns of magnesium accumulationGualano, L. D. (1)Moriconi, J. I. (1); Tranquilli, G.E.(2); Santa-María G.E. (1)(1) Instituto Tecnológico Chascomús (INTECH), CONICET-UNSAM, Chascomús, Argentina; (2) Instituto de Recursos Biológicos, INTA. Hurlingham, ArgentinaThe structural rearrangements resulting from the recombination of the rye (Secale cereale) chromosome 1RS with chromosome 1BS of bread wheat (Triticum aestivum) determine relevant agronomic consequences. Two near isogenic lines derived from that recombination, designated as 1RS and 1RW, differ in a relatively small region of the short chromosome arm. We have recently reported that such rearrangements imply modifications in the dosage of genes, which confer notable differences in drought resistance in a way primarily associated to differential capacity for soil exploration by the roots. An emerging question from such work is whether or not those rearrangements also influence differentially the ionome of these lines. We performed two independent studies of the ionome which unveiled the existence of relevant differences between 1RS and 1RW lines in the distribution of magnesium (Mg) between the shoot and the root. Our work also revealed that such differences occur over a wide range of Mg supply, being them attributable to inequalities in the specific rates of absorption and translocation of this element. A detailed study of the movement of water through the apoplastic and non-apoplastic pathways of radial transport, by using a fluorescent dye, indicates a minimal contribution of the bypass flow in both lines, which converges in assigning the differences found in Mg translocation to non-apoplastic routes, particularly those involving transport processes operating on biological membranes. The analysis of a comparative study of the transcriptome, formerly done for an apical segment of the roots of RS and RW plants, suggests that, at least in this zone, notable differences would occur in the expression of genes that encode cation transporters.magnesium accumulation, wheat, plant physiology
Is soybean leaf senescence modulated by direct and indirect effects of post-flowering photoperiod?Santiago Julián KellyCano, M.G.(1);Tambussi, E.A. (1); Guiamet, J.J. (1)(1) Instituto de Fisiología Vegetal, UNLP-CONICET, ArgentinaIn soybean (Glycine max L. Merr) massive senescence of leaves coincides with pod and seed development, and this has been interpreted as evidence for a correlative control exerted by the pods and triggering senescence of leaves. Soybeans are short-day plants for flowering and long photoperiods after anthesis delay pod development, and senescence. Although pods modulate leaf senescence there are also reports showing some changes of leaf senescence that cannot be associated exclusively with pod development; implying that other factors (e.g., photoperiod per se) could modulate senescence regardless of the effect of pods. The objective of this work was to analyze if post-anthesis photoperiod might regulate the progress of leaf senescence both through its effects delaying the development of pods (an indirect effect) and independently of the development of the pods (a direct effect). After anthesis, soybean plants were exposed to photoperiod treatments (short days, SD, vs long days, LD) combined with a pod removal treatment (plants with pods vs without pods). The progress of leaf senescence was determined from SPAD 502 measurements of leaf chlorophyll content. In plants with pods, post-anthesis LD delayed reproductive development together with a delay in leaf senescence compared to plants exposed to SD. On the other hand, in de-podded plants, post-anthesis LD also delayed leaf senescence in relation to plants exposed to SD.There also were differences in leaf senescence under LD in plant without pods vs. plants with pods. These results indicate that photoperiod is a factor that modulates leaf senescence both indirectly (i.e., mediated by the delay of pod development) and directly (i.e., independently of pod development).Therefore, in addition to source-sink effects, leaf senescence in soybean is directly regulated (at least partially) by photoperiod.leaf senescence, photoperiod, indirect effect, direct effect, soybean
Impact of stomatal density on the hydraulic properties of Arabidopsis thaliana: Studies on transpiration rate and root hydraulic conductivityCáceres Pablo DanielSutka, M. (1); Sampaolesi M.R. (1); Fiorini T. (1); Amodeo G. (1); Baroli I. (1)(1) Departamento de Biodiversidad y Biología Experimental (DBBE, FCEyN-UBA) and Instituto de Biodiversidad y Biología Experimental Aplicada (IBBEA, UBA-CONICET), Buenos Aires, ArgentinaPlants have the ability to maintain optimal water status in response to environmental changes, tolerating stress conditions by modifying their hydraulic parameters. Among the main adjustment mechanisms are the regulation of stomatal opening and closure, as well as water conduction properties in plant tissues. Particularly, the efficiency of water transport at the cellular level is influenced by membrane permeability, which is regulated by intrinsic facilitating proteins known as aquaporins. In this study, we investigated the relationship between hydraulic properties of roots and rosettes in lines of Arabidopsis thaliana with mutations in the EPF1 and EPF2 genes, resulting in a 2.5-fold increase stomatal density and a higher transpiration rate. We investigated whether the higher transpiration rates correlated with the plant´s hydraulic properties. For this purpose, we used the hydroponic cultivation to preserve the root system completely intact. Although we observed 23% increases on transpiration rates in the epf1 epf2 double mutants plants, we found no significant changes on root hydraulic conductivity, aquaporin contribution to root water transport, root and leaf osmotic potential, or leaf relative water content. Additionally, we present the analysis comparing the expression profile of water-transporting specialized aquaporins between mutant and wild-type plants. These findings suggest that Arabidopsis plants grown under favorable conditions have the ability to maintain similar root hydraulic conductivity, even when faced with a significant increase on transpiration rate. These findings contribute to our understanding of hydraulic regulation mechanisms in plants and their adaptation to different environmental conditions.plant physiology, Arabidopsis thaliana, stomatal density, transpiration rate, hydraulic properties, root hydraulic conductivity
RS31: a novel player involved in the regulation of light-induced seed germination and flowering in Arabidopsis thalianaTognacca, R.S. (1,2)Rodríguez, F.S. (1,2); Cartagena, C.M. (1,2); Servi, L. (1,2); Kalyna, M. (3); Petrillo, E. (1,2); Tognacca, R.S. (1,2)(1) Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología, Molecular, y Celular, Buenos Aires, Argentina. (2) CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), C1428EHA, Buenos Aires, Argentina. (3) Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences Vienna, Vienna 1190, Austria.Seed dormancy is a developmental checkpoint that prevents mature seeds from germinating under conditions that are otherwise favorable, allowing plants to regulate when and where they grow. Primary dormancy refers to the innate dormancy possessed by seeds when they are dispersed from the mother plant. Temperature and light are the most relevant environmental factors that regulate seed dormancy and germination. These environmental cues, that can trigger molecular and physiological responses (including ABA and GA signaling), induce a massive reprogramming of gene expression, and shape the seed transcriptome by affecting each possible level of gene expression such as mRNA splicing, translation, and stability. The expression of many genes that regulate dormancy, germination and flowering can be modulated by alternative splicing (AS, a co-transcriptional mechanism that generates transcriptome diversity) in response to the environment. We have previously shown that when Arabidopsis seeds receive a pulse of Red light, the AS pattern of the splicing factor RS31 is drastically changed. Here, we show that seeds overexpressing the RS31 coding isoform (namely mRNA1) do not show primary dormancy and germinate even under suboptimal light conditions, suggesting that mRNA1, ergo the RS31 protein, has a key role during the establishment of primary dormancy and functions during light-induced seed germination. Accordingly, ABA- and GA-related genes have altered expression levels. We also show that overexpression of the mRNA1 delays flowering under SD and LD conditions when compared to the wild type, suggesting that RS31 is also involved in the regulation of this process. Overall, affecting alternative splicing may also alter key physiological traits.dormancy, germination, flowering, seeds, light
Unveiling hidden regulators: exploring non-coding transcripts arising from alternative splicing and their impact on protein functionRodríguez, F.S. (1,2)Tognacca, R.S. (1,2); Servi, L. (1,2); Legascue, M.F. (3); Ariel F. (3); Petrillo, E. (1,2).(1) Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología, Molecular, y Celular, Buenos Aires, Argentina; (2) CONICET-Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), C1428EHA, Buenos Aires, Argentina; (3) Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000, Santa Fe, Argentina.Alternative splicing (AS) produces multiple transcripts from a single gene through a variable and regulated selection of splice sites. Different isoforms can be translated into different proteins. In addition, AS can also give rise to non-coding variants, which tend to degrade, allowing delicate regulation of the levels of coding isoforms and of the amount of protein generated. However, non-coding transcripts can also control chromatin status, modulate the abundance of other RNAs and even translation.
Light is an important environmental cue that influences gene expression and AS. The serine-arginine rich protein At-RS31, undergoes AS in a light-regulated fashion. As a result, the coding isoform mRNA1 is accumulated in light whereas the non-coding isoform mRNA3 accumulates in darkness. We demonstrated that Arabidopsis seedlings overexpressing mRNA1 (mRNA1ox) have a deleterious phenotype, while the overexpression of the genomic construct generates seedlings with a normal phenotype. We hypothesize that mRNA3 is the cause of this phenotype reversion. Since we showed that the mRNA3 remains in the nucleus and accumulates as time in darkness increases, we generated transgenic mRNA3ox and mRNA1ox/mRNA3ox plants to test for phenotype reversion under different physiological conditions. We found that mRNA1ox/mRNA3ox plants behave as wild-type under our experimental conditions. By using bioinformatic and molecular approaches we found other stable, nuclear-retained, non-coding isoforms that could have a potential regulatory function/s as the mRNA3. We are currently evaluating the interaction between the non-coding isoform and the protein generated by the coding isoform of the same gene to check an autoregulatory loop is underlying the mechanism of action. This will help us testing our central hypothesis, that the mRNA3 modulates the activity of the RS31 protein.


alternative splicing, non-coding isoforms, light, Arabidopsis
Natural coating for inoculant delivery in bean seedsMelchiorre MarianaSarmiento, A. (1), Lattanzi, S. (1), Grasso, F. (1), Montoya, P. (1), Melchiorre, M. (1, 2)1). Facultad de Ciencias Exactas Físicas y Naturales UNC 2). UDEA Unidad de Estudios Agropecuarios (INTA-CONICET)Biofertilization is a sustainable way to increase crop yields; however, there is little technological development to deliver supplies on seeds. A biopolymeric coating for Leales 22 INTA Alubia beans  (Phaseolus vulgaris L.) was formulated as a natural and biodegradable matrix, allowing the incorporation and survival of inoculants. The coating was applied with a professional LS_BLab pilot scale seed treater.

A comercial product containing Rhizobium tropici and Rizhobium etli was used as inoculant and Premax® was tested as rhizobia protector. The biopolymer was applied on seeds using 15 mL/kg. The treatments evaluated were: coated and uncoated seeds (R, NoR), with or without inoculant (I, NoI) and with or without Premax®  (P, NoP).

The biopolymer adhesiveness and response against friction in seeds were tested as mechanical properties. Moisture content (%MC) was assayed, resulting significantly lower (9.45% MC) in RINoP compared to 9.67% MC for NoRIP seeds. Static friction coefficient (Cf) is a relevant physical property that affects sowing operations. High values indicates higher slip-resistance. In RINoP seeds, Cf was 0.28, whereas in RIP and NoRIP were 0.31 and 0.32 respectively, showing that the coating did not increase the coefficient.

Biological responses were analized by germination and nodulation. Coated and uncoated seeds did not show differences in time of germination or percentages. Nodule number and their weight in plants from RIP and RINoP seeds were significantly higher than nodules developed from  NoRIP seeds.

Recovery of viable rhizobacteria on plates was determined as UFC/mL up to 42 days using treated seeds as microorganisms source. From NoRIP seeds, rhizobacteria survival was considerably lower than in RIP and RINoP. Premax® did not show protective effect when RIP and RINoP were compared. It can be inferred that the biopolymer offerred an adecuate matrix that guaranteed rhizobia survival on coated seeds up to 42 days after treatment.
Biopolymer, Seed coating, bean, Phaseolus vulgaris
Temperature and shade: How plants perceive and transduce different signals with common sensors?De Luca Maria BelenMurcia Germán (2); Bianchimano Luciana(2); Iglesias María José(3); Casal Jorge J(1,2).(1) Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomía, Buenos Aires, Argentina. (2) Fundación Instituto Leloir and IIBBA-CONICET. Av. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina. (3) Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-UBA, Buenos Aires, Argentina.Plants have a high degree of plasticity and have developed complex mechanisms to perceive environmental signals. The current trend is to use a greater number of plants per unit area causing more intense shading within the canopy, and because of climate change, plants are also exposed to higher average temperatures. The mechanisms of perception and signaling of light and temperature share molecular components, including phyB acting as photoreceptor and thermosensor. Furthermore, shade and temperature involve modifications of the redox state by reducing the light available for photosynthesis and affecting photosynthesis and respiration, respectively. Shade reduces the level of irradiance and this has been repeatedly linked to the generation of reactive oxygen species (ROS). The reactive nitrogen species (RNS) and reactive sulfur species (RSS) are closely related to ROS. These species can function as signaling molecules in growth and transduce signals through redox posttranslational modifications of cysteine (Cys) residues. In this work, we studied the role of H2S as RSS as a cellular messenger in the promotion of hypocotyl growth under shade, temperature or the combination of both treatment in Arabidopsis thaliana and Brasica napus. We observed distinctive patterns of persulfidation, Cys modification triggered by H2S, in hypocotyls and cotyledons under shade and temperature signals. We are identifying targets of Cys persulfidation acting as common or specific components downstream phyB perception of changes in shade or temperature.Temperature, Shade, Thermosensor, Reactive Sulfur Species
The DC1 domain protein VACUOLELESS GAMETOPHYTES is necessary for Arabidopsis reproductive organ development and anther dehiscenceAmigo Natalia LoreleyArias, L.A.; Marchetti, F.; D´Ippolito, S.; Lombardo, C.; Casalongue, C.A.; Pagnussat, G.C.; Fiol, D.F.Instituto de Investigaciones Biológicas, IIB-CONICET-Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.VACUOLELESS GAMETOPHYTES (VLG) is a DC1 domain protein that was first characterized in our laboratory as essential for early female and male gametophytic development in Arabidopsis. VLG expression was also detected in stamens, pistils and other sporophytic tissues, mainly following a vascular distribution, implying a broader role for this protein during reproductive development. As VLG mutation is strongly deleterious for gametophytic development, homozygous lines are unavailable. Therefore, in order to explore the possible role of VLG in flower development, we generated three knockdown Arabidopsis VLG lines, using amiRNA induced target messenger degragation, referred to as amiR-VLG. The phenotypic characterization of amiR-VLG plants showed reduced seed set as a result of deficient anthesis. This was partially caused by undehisced anthers with shorter filaments and an excessive gynoecium elongation, known as stigma exsertion. Moreover, amiR-VLG displayed unbroken stomia and septa, as well as markedly reduced endothecium lignification and lack of the ROS accumulation necessary for lignin biosynthesis. The indehiscent phenotype was rescued by either exogenous jasmonic acid (JA) or H2O2 treatments. In fact, silencing of VLG causes the down-regulation of JA biosynthesis and lignin biosynthesis transcripts. Altogether, our results suggest that the expression of VLG is upstream of lignin and JA biosynthesis, which together are essential for stomium breakage and proper anthesis. Our findings shed light on the molecular mechanisms underlying stamen development and provide new insights into the roles of DC1 domain proteins in plant reproduction.Stamen development, anthesis, Jasmonic Acid, Reactive oxigen species, lignin biosynthesis.
Physiological classification of drought tolerance in soybean genotypesBustamante OrianaBustamante OM1*, Posada GA2, Suarez P1, Espinosa Herlein MA1, Monteoliva MI1, Guzzo MC1.1-Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV-UDEA), CIAP, INTA-CONICET, Córdoba, Arg. 2-FCQ, UNC *bustamante.oriana@inta.gob.arDrought is one of the most limiting environmental factors in agriculture. Water deficit reduces plant growth and alters development, reducing crop yields. Soybean is one of the most important crops worldwide in grain productivity and sown area. To improve productivity under drought, it is relevant to identify and characterize tolerant soybean genotypes. Drought tolerance could manifest in physiological responses, such as higher relative water content (RWC), fresh and dry biomass accumulation, or biochemical responses such as higher chlorophylls, proline, or FRAP, or lower MDA (oxidative damage). This project aimed to classify soybean genotypes under controlled drought. We evaluated soybean lines from EEA Marcos Juárez (INTA), grown in a greenhouse, with supplemental light and temperature control. All plants were well watered until the second trifoliate leaf emerged. Then, half of the plants were subjected to water shortage. They were daily monitored until soil moisture reached 30% of soil maximum capacity and kept at that level for one more week when they were measured and harvested. We found variability in stress responses, with genotypes that keep a higher RWC than 70%. Greenness increased under drought for all materials. We also found variability in proline, FRAP, and chlorophyll responses.

Funds: INTA-PE-2019-I127, INTA-PD-2023-I084, INTA-PE-2023-I111, PICT 2018-01326.
Glycine max, germplasm, water deficit, legumes, phenotyping
OXR2 proteins improve UV-B tolerance in ArabidopsisEusebi, Delfina (1)Sheridan, María Luján (2); Casati, Paula (2); Welchen, Elina (1,3)(1) Instituto de Agrobiotecnología del Litoral (IAL-CONICET-UNL). (2) Centro de Estudios Fotosintéticos y Bioquímicos, CEFOBI, Argentina. (3) Cátedra de Biología Celular y Molecular (FBCB-UNL).Arabidopsis plants overexpressing AtOXR2 and its sunflower homolog HaOXR2 (oeOXR2 plants) showed beneficial phenotypic characteristics, including increased tolerance to UV-B radiation, evidenced by higher root growth rate compared to WT, after the UV-B exposition. We previously demonstrated a reduced number of root meristem cells’ death after the UV-B challenge using propidium iodide staining. Furthermore, we found less DNA damage in 7-day-old UV-B irradiated oeOXR2 seedlings when analyzing pyrimidine dimer formation through Dot-Blot analysis. We assessed the activation of the UV-B response in oeOXR2 plants. Following UV-B exposure, COP1 transcript levels were reduced, while HY5 and RUP1 increased their expression relative to WT. Our investigation of the DNA repair pathways against UV-B damage revealed that the transcript levels of UVR2, UVR3, and UVR7 genes were already higher under normal growth conditions and significantly increased after UV-B exposure in oeOXR2 plants. However, oeOXR2 plants also exhibited altered expression of several genes involved in controlling cell proliferation in the root meristem. Specifically, the S phase marker gene H4 and KNOLLE decreased their expression after UV-B treatment. In contrast, CDKB1.2 (G2 phase marker) tended to be higher in control and after UV-B treatment in oeOXR2 compared to WT plants. Furthermore, the expression of transcripts for antioxidant enzymes was also altered, indicating that AtOXR2 and HaOXR2 can modulate antioxidant enzyme expression in Arabidopsis both under control conditions and when subjected to UV-B stress.
The increased tolerance to UV-B radiation observed in oeOXR2 plants is likely due to four interconnected factors. These include a more efficient antioxidant pathway, improved dynamics in UV-B radiation perception, basally activated DNA damage repair, and an altered cell cycle to allow DNA repair, thereby preventing the spread of damage throughout the entire plant.
UV-B radiation, OXR proteins, stress resistance
Flower bud abortion is associated with cavitation sensitivity in cotton (Gossypium hirsutum) cultivar.Colli, Sergio LeonardoTarrago, J.R (1); Mignolli, F (2)(1) INTA E.E.A Las Breñas, Argentina. (2) Instituto de Botánica del NordesteCotton (Gossypium hirsutum L.) is one of the most important crops worldwide, with fibre and oil being its primary products. In situations of high temperatures and low relative humidity, abortions of floral buds occur at a very early stage of their development. The aim of the present work was, on the one hand, to relate the abortions of reproductive structures with the environmental conditions and, on the other, to infer it with the susceptibility to cavitation. The study was conducted with three cotton varieties (DP1238, DP50 and BGSP6635) grown in pots and subjected to different soil moisture levels: 20, 50 and 85% of field capacity. From the appearance of the first flower bud, a count of the number of total and aborted shoots was carried out. At the same time, cavitation vulnerability curves (CVC) were performed in petioles and stems using the air injection method. The cultivar DP 1238 presented the highest percentages of abortions (66.9 %) regardless of the soil's moisture level. Whereas, DP50 and BGSP6635 showed a higher number of aborted shoots in conditions of low water content in the soil, reaching 29.3 % and 5.3% of abortions, respectively. The abortion peaks coincided with ​high temperatures and low relative humidity on the day before the measurement. CVC is the pressure required to decrease by 50% of the initial hydraulic conductivity. In stems and petioles of DP1238, CVC was -1.3 and -0.5 Mpa, respectively. In BGSP6635, it was -1.32 and -1.5 Mpa, while in DP 50, it reached -0.75 and -1.21 Mpa. The very negative CVC values ​​in the BGSP6635 cultivar could indicate a higher resistance to cavitation, consistent with the lower number of flower bud abortions. Diversely, in DP1238 and DP50, higher CVC values ​​in petioles, in particular, would explain the high percentage of abortions resulting from embolism.Cavitation susceptibility, Cotton; Square Shedding
Function of Plant Glutamate Receptor-like channels (GLR) in adaptation to abiotic stressErwan Michard (1)Simon, A (2); Navarro, C (1,2); Wudick (2), M; Feijo, JA (2)(1) Universidad de Talca, Chile, (2) University of Maryland, USASensing of abiotic stress involves the sensing of various biophysical parameters, including pH, redox potential, mechanical and chemical cues. Downstream stress sensing, the transduction of the stress signal is ensured by more or less specific transduction pathways where second messengers, phosphorylation cascades, voltage changes play major roles. Plant ionotropic glutamate receptors (GLRs) are strategically located within the network: on one hand GLRs participate in signal propagation by permeating the second messenger Ca2+ and transporting other ion species that control membrane voltage. On the other hand, GLR activity is sensitive to several key signal messengers including amino-acids ACC, D-serine, Glutamate, second messengers H+, Ca2+, electric and redox potential. I will present electrophysiological data acquired in heterologous system expressing plant GLRs and characterizing their regulation. So far, the mechanism of action of GLR in the context of cell signaling has been elusive. I will discuss the consequences of the data presented on role of GLRs in signal propagation and transduction in the context of abiotic stress response.Calcium, channel, abiotic stress, physcomitrella patens, moss
Isolation of tissue-specific nuclei to study transcriptional changes associated with strain preference in the nitrogen fixing symbiosisCretton MarinaBarbán, M; Zanetti, M. E; Reynoso, M; Blanco, F.Instituto de Biotecnología y Biología Molecular (IBBM) - CONICET - UNLPThe nitrogen-fixing symbiosis is initiated by the recognition between legume roots and rhizobia. To understand the genetic bases of this compatibility at the level of sub-species, we focused our studies in the transcriptional control of the symbiosis between common bean (Phaseolus vulgaris) and specific strains of Rhizobium etli. The main objective of this work is to study the epigenetic changes that occur in response to rhizobia strains that are more efficient in the root nodule symbiosis at tissue-specific level. We adapted the INTACT technique (Isolation of Nuclei Tagged in specific Cell Types) to common bean using transient transformation by Agrobacterium rhizogenes. The methodology is based on the expression of a fusion protein called NTF composed by the WPP interacting protein (WIP), the Green Fluorescence Protein (GFP) and the biotin acceptor domain (BLRP). A biotin ligase is expressed from another transcriptional unit in the same vector to produce biotinylation of BLRP. In this way, nuclei that contain the Nuclear Tagging Fusion can be purified using magnetic beads associated with streptavidin. When the Nuclear Tagging Fusion is expressed under the control of a cell-specific promoter, the technique allows purifying nuclei from that individual cell-type. Constructs with the nearly constitutive CaMV35S promoter and tissue-specific promoters (pExpansin7 for epidermis and PEP for cortex) upstream from the WIP-GFP fusion are being used to transform P. vulgaris root by A. rhizogenes mediated transformation. Expression of the p35S-NTF construct in transgenic roots was confirmed by western blot and the observation of fluorescent nuclei in root sections under a confocal microscope. In addition, isolation of nuclei using INTACT was revealed by propidium iodide staining after affinity purification. We are currently preparing nuclei from roots inoculated with strains exhibiting different symbiotic outputs to compare nuclear RNA populations and chromatin modificationscommon bean, symbiosis, rhizobium, INTACT, nuclei, epigenomics
Expression of the alfalfa gene MsMDHAR increases root biomass and promotes tolerance to hydric stress in transgenic Arabidopsis.Jaime, C.L. (1)Dezar, C. (1); Pagán Muñoz I. (2); Dunger G. (1,2)(1) ICiAgro Litoral (UNL-CONICET). (2) Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA)Alfalfa (Medicago sativa L.) is the world's main forage crop, forming the basis for meat and milk production. Argentina is one of the leading alfalfa producers globally, with 3.5 million cultivated hectares. However, its persistence has decreased over the years due to climatic variations, soil degradation, and the relocation of its production to marginal areas.
The ascorbate-glutathione pathway is a critical component of the plant defence system and it is responsible for regulating the cellular redox state, which is critical for maintaining cell function and survival under adverse conditions. Monodehydroascorbate reductase (MDHAR) is an essential enzyme of this cycle, being responsible for the regeneration of ascorbate, which is a potent antioxidant molecule. To study the function of MsMDHAR and its possible role in conferring hydric stress tolerance, we expressed this gene constitutively in Arabidopsis thaliana.
First, the expression of MsMDHAR in different homozygous transgenic events of Arabidopsis was measured, and two of them were selected for phenotyping under control and abiotic stress conditions. It was found that transgenic plants developed more root biomass in control or hyperosmolarity conditions. To evaluate abiotic stress tolerance in the MsMDHAR-expressing Arabidopsis, plants were grown for 3 weeks in a greenhouse and then subjected to drought and waterlogging during two additional weeks. After that, dry weight of the rosette, inflorescence and seed production of the transgenic lines were evaluated. Expression of MsMDHAR seems to increase tolerance to drought and waterlogging in Arabidopsis, indicating that this enzyme plays an important role in plant stress responses. These preliminary results provide a basis for the development of alfalfa lines with improved tolerance to abiotic stresses via the manipulation of MsMDHAR expression.
Alfalfa, Arabidopsis, Hydric stress
Cytochrome c levels establish a mitochondrial connection to SnRK1 pathway activity for the regulation of growth and metabolismFlorencia P. CoronelDiana E. Gras, M. Victoria Canal, Elina Welchen and Daniel H. GonzalezInstituto de Agrobiotecnología del Litoral (CONICET-UNL)In eukaryotic organisms, respiration takes place in mitochondria and involves the transport of electrons through cytochrome c (CYTc), a small heme protein that participates in electron transport coupled to ATP synthesis. CYTc-deficient plants have shorter roots, smaller rosettes and delayed growth, probably due to an alteration in energy availability. Here, we studied a possible connection between CYTc and the SNF1 (sucrose non-fermenting 1)-related protein kinases 1 (SnRK1) pathway, involved in adjusting cellular metabolism during carbon starvation and stress conditions. First, we analyzed the activation of the pathway by measuring SnRK1 phosphorylation levels and the expression of SnRK1 target genes DIN6 and SEN5. The results suggested that the SnRK1 pathway is activated in CYTc deficient plants and downregulated in plants that overexpress CYTc. Secondly, we performed crosses between the CYTc mutant line cytc_1a and plants with low SnRK1 pathway activity (akin10-2). Phenotypic and molecular analyses indicated that several alterations observed in plants with CYTc deficiency are due to activation of the SnRK1 pathway, likely mediated by changes in mitochondrial energy production. These alterations include reduced growth, delayed reproductive development, increased free amino acid content and increased autophagy, among others. Our results suggest that CYTc levels affect the activity of the SnRK1 pathway to adjust growth and metabolism according to changes in mitochondrial activity.CYTc; SnRK1; Growth; Arabidopsis
Effect of R-loop near MIRNA transcription start site region on co-transcriptional processing and miRNA movementJosefina FernándezGonzalo L. (1); Manavella, P. (1)(1) Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Argentina.MicroRNAs (miRNAs) are small RNA molecules, approximately 21 nucleotides in length, crucial for multicellular organisms development. MiRNAs are encoded by MIRNA genes, which, when transcribed by RNA polymerase II (RNAPII), produce structured primary transcripts known as pri-miRNAs. These pri-miRNAs are recognized by the processing complex formed by DICER LIKE 1 (DCL1) in association with SERRATE (SE) and HYPONASTIC LEAVES 1 (HYL1). The processing of pri-miRNAs can occur after transcription or during transcription, while the pri-miRNA is still associated with the RNAPII (co-transcriptional processing). Both mechanisms co-exist, and their balance depends on development stages and growing conditions. Interestingly, R-loops (DNA:RNA hybrid) near the transcription start site (TSS) of MIRNA genes promote co-transcriptional processing. Furthermore, a high co-transcriptional processing rate correlates with the capacity of miRNAs to move out of the cell. To study the relationship between R-loops and non-cell autonomous miRNA function, we used transgenic lines of Arabidopsis containing the construction promSUC2::amiRSUL. The SUC2 promoter specifically expresses in phloem cells, and the artificial RNA (amiRSUL) degrades the CHLORINE42 (CH42 or SUL) mRNA, resulting in chlorosis in the vascular system after the mature miRNAs move from cell to cell. Here, we expressed a long non-coding RNA (lncRNA) capable of forming a R-loop near the TSS of amiRSUL and evaluated the range of amiRSUL movement. R-loop is expected to enhance co-transcriptional processing, increasing amiRSUL cell-to-cell movement. The increase in amiRSUL movement will be detected using two techniques: quantification of chlorosis expansion through image analysis and measurement of chlorophyll levels in the leaves of both transformed and control plants. This study aims to understand whether the presence of R-loops and high levels of co-transcriptional processing could lead to the neofunctionalization of mature miRNA.pri-miRNA processing, antisense R-loops, mobile miRNAs
Enhancing insight into the function of plant filamentous-pathogens' Effectors: suppression of immunity via manipulation of developmental hormonal pathGeorgina FabroBogino, María FlorenciaCIQUIBIC-CONICET CCT Córdoba, Dpto. Química Biológica, Fac. Cs. Químicas, Universidad Nacional de CórdobaFilamentous pathogens, such as oomycetes and fungi, produce a wide array of molecules during their interactions with plant hosts. Among these, effector proteins play a crucial role as specialized weapons that these pathogens deliver into plant tissues. By generating and delivering multiple effectors at different stages of infection, pathogens manipulate various cellular and metabolic processes to create a favorable environment for survival and reproduction. They also undermine host immunity to access nutrients and building blocks. Our research focuses on effector biology, aiming to identify the plant targets of these effectors, uncover their molecular activities, explore their recognition by resistance proteins, and assess the potential to generate resistance by eliminating susceptibility factors. We specifically delve into understanding the virulence mechanisms of effectors involved in the balance between defense signaling and growth signaling. Comprehending the molecular basis of these tradeoffs is crucial for developing resistant plants without compromising growth, ultimately maximizing crop yields.filamentous pathogen, oomycete, effector, immunity, growth-hormones.
Screening of endophytic bacteria by protection against water deficit in peanut plantsEspinosa HerleinEspinosa Herlein MA1,3, Ruiz, OA2,3, Guzzo MC1, Monteoliva MI1,31-Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV-UDEA), CIAP, INTA, Córdoba, Arg. 2-INTECH, Chascomús, Buenos Aires, 3- CONICETOne of the most frequent and damaging environmental stresses worldwide is drought or water deficit. Drought can reduce photosynthesis rates, inhibit growth, and cause yield and grain quality drops in crops. To reduce the losses by drought, we aim to find beneficial bacteria able to protect peanut plants against the negative effects of stress. Endophytic bacteria are microbes that colonize and proliferate inside the plant tissues without causing any damage. They colonize mostly the intercellular space.

Previously we classified 76 bacteria isolates from peanut crop, according to their osmotic tolerance in vitro. This project aimed to classify endophytic bacteria from peanuts according to their protective effect against drought in vivo. We carried out greenhouse experiments in peanut plantlets (the commercial Granoleico cultivar). We inoculated the seedlings and then sprayed the leaflets two more times before the drought onset. Then we started the water deficit by reducing the irrigation. We kept plants uninoculated plants, both under drought and sufficient irrigation, as controls. When soil moisture reached 15% of the maximum soil water content, physiological responses (such as relative water content -RWC- and leaf temperature as transpiration marker) and total shoot biomass were measured.

We observed variability in the evaluated responses. RWC varied between 50 and 75% (water deficit controls showed 60% as average). We also found variability in transpiration and biomass accumulation. Till the moment, we have one isolate with RWC over 70% and a higher transpiration rate than uninoculated controls, which is a strong candidate for further characterization.

Funds: INTA-PD-2019-I069, INTA-PE-2019-I516, INTA-PD-2023-I084, -I085, -I071, INTA-PE-2023-I073, PICT 2018-0065, PICT 2018-01326.
legumes, bioinputs, drought, plant protection, abiotic stress
Genetic and physiological mechanisms responsible for maize kernel weight and source-sink relations under contrasting nitrogen supply levelsIgnacio HisseD'Andrea, K.E. (1,2); Otegui, M.E. (1,3)(1) Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Buenos Aires, Argentina. (2) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. (3) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) en INTA, Centro Regional Buenos Aires Norte, Argentina.Agricultural production is requesting the use of increasingly efficient inputs, especially those with high environmental pollution-risk associated, as in the case of nitrogen fertilization. Consequently, analyses performed under N stress conditions are highly desirable; however, studies based on grain yield genetic control in suboptimal environments are scarce, particularly those associated with the physiological components responsible for the individual kernel weight determination (KW). The main objective was to evaluate the genetic and physiological mechanisms underlying maize grain yield determination under contrasting soil nitrogen availability. A set of traits formed by KW and grain-filling traits, kernel number, plant growth during the critical and grain-filling periods, and source-sink relationships in both periods were analyzed on six inbred lines from different origins and their 30 single-cross derived hybrids, using a full diallel mating design. Under contrasting nitrogen supply, differences in KW were mainly attributable to changes in the source-sink ratio during grain filling (r2≥0.50, P<0.001) because of an enhanced post-flowering growth at a high N level. This was evident for hybrids but not for inbreds, probably due to the negative inbreeding depression effects on traits controlling seed expansion. At low nitrogen (i) broad-sense heritability estimates were increased (43% on average) for grain-filling traits but were reduced (5% on average) for most plant growth traits and source-sink relationships, and (ii) the proportion of additive genetic effects (i.e., heritable) was increased for most traits. Those traits representative of kernel water dynamics had higher heritability and additive effects than KW, particularly under low nitrogen. Enhanced additive effects and heritability at the low nitrogen level support the idea of increased selection efficiency under low-input conditions, particularly for grain-filling traits.Zea mays L, grain weight, nitrogen offer, genetic analyses, secondary traits.
Morphological diversity, selective signals and evidence of local adaptation in Argentinean maize landracesFreilij, DamiánFreilij, D. (1); Defacio, R.A. (2); Heck, M. I. (3); Fariza, S. I. (3); De Lucia, A. D. (3); Ferreyra, M. (4); Paniego, N. B. (1); Domínguez, P. G. (1); Lia, V. V. (1,5)(1) Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Hurlingham, Buenos Aires, Argentina. (2) Estación Experimental Agropecuaria INTA Pergamino, Pergamino, Buenos Aires, Argentina. (3) Estación Experimental Agropecuaria INTA Cerro Azul, Misiones, Argentina. (4) Estación Experimental Agropecuaria INTA Salta, Salta, Argentina. (5) Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.The northern region of Argentina is home to more than 60 native maize landraces, with two main genetic groups of high phenotypic variability: the high-altitude Andean landraces, present in northwestern Argentina (NWA), and the floury landraces of the northeast (NEA). This work evaluated 9 accessions from each region by means of reciprocal transplant gardens (Maimará, Jujuy & Cerro Azul, Misiones) in order to demonstrate their local adaptation. The variability of 14 agro-morphological and 6 phenological and yield characters was studied using general linear mixed models. NEA landraces showed higher mean phenotypic values, while the NWA ones showed the highest variation in both environments, with a negative correlation between collection altitude and most of the traits. Morphological structuring assessed by a discriminant analysis of principal components (DAPC) revealed the existence of groups unique to each region and a high degree of admixture, with each accession consisting of more than one of the inferred groups. The Andean NWA group was the most consistently recovered in cluster analyses, while NEA maize was divided into two groups not concordant with prior divisions. The search for selective signals used PST - FST comparisons, representing morphological and molecular neutral divergence, respectively. Directional selection signals were detected both within and between regions at most traits, being strongest at the region level and varying in magnitude between gardens. Moreover, fitness values in the NEA garden, measured as the number of plants with good seed quality per plot, showed maladaptation and low yields of NWA maize outside its native range.

Taken together, our analyses suggest that several traits mediate local adaptation in maize landraces from northern Argentina. From a broader perspective, the extensive variability found within regions highlights the need to consider this source of variation in the design of in situ and ex situ conservation programs.
fitness, landrace, local adaptation, phenotype, population genetics, reciprocal transplant, Zea mays ssp mays
Physiological and biochemical responses to drought in Eucalyptus and their relationship to drought and freezing tolerance.Margarit, E.Oberschelp, G.P.J. (2), Salto, C.S. (2), Harrand, L. (2), Margarit, E. (1)(1) Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET). Suipacha 570, Rosario, Santa Fe. (2) Instituto Nacional de Tecnología Agropecuaria (INTA) Ruta 22 y vías del ferrocarril, CP E3200AQK, Estación Yuquerí, Concordia, Entre Ríos, Argentina.Drought and frost can affect eucalypts plantations in the early stages of cultivation, causing economic losses. However, plants can activate physiological and biochemical responses to prevent or reduce the effects of one or both stresses. Some of these mechanisms, such as the accumulation of compatible solutes, have been reported to help prevent dehydration and cell damage. Identifying these mechanisms in Eucalyptus species is key to the application of genetic improvement techniques. In this work, we evaluated the drought and freezing tolerance as well as the physiological and biochemical responses in seedlings of four Eucalyptus species (E. grandis, E. benthamii, E. dunnii, E. grandis x E. camaldulensis) subjected to water stress and control treatments. E. benthamii (Eb) showed high tolerance to water stress. Eb, together with E. dunnii (Ed), also showed high tolerance to freezing. However, all species were able to induce freezing tolerance as a result of applied water restriction. Interestingly, several physiological parameters (RWC, LA, LDW, SLA) were less sensitive to drought treatment in Eb. Biochemical studies indicated that Eb accumulated amino acids and compatible solutes such as myo-inositol or quinic acid, although all species showed sugar accumulation responses. The leaf proteome study identified 1,843 proteins and revealed differences at both species and treatment level. In particular, it was possible to identify that the adjustment of metabolism, photosynthesis, and some protective mechanisms could play an active role in protecting plants of this and other genera against different stresses. The species tested showed different responses to water restriction and different tolerances to drought and freezing. Biochemical studies linked metabolites and proteins to the observed tolerances. This study opens the door to identifying tolerance mechanisms and breeding traits for species of productive interest.Eucalyptus, frost, drought, stress, tolerance, physiology, metabolomics, proteomics.
Convergence between splicing and miRNAs machineries in plantsContino GiulianaAgrofoglio, Y. (1); Frixione, L. (1); Fera, J. (1); Iglesias, M.J. (1); Mateos, J.(1)(1)Instituto de Fisiología, Biología Molecular y Neurociencias ,IFIBYNE, Argentina.Plants adapt to the local environment by dynamically shaping their transcriptome. For this, post-transcriptional mechanisms play a key role. Alternative splicing, which generates several mature RNA isoforms from the same primary transcript, and microRNAs (miRNAs) that allow fine tuning gene expression in a fast and precise manner, have been shown to be important for a proper response of the plant to a changing environment. The proteins involved in both processes share similar functional characteristics, such as RNA recognition, RNA binding and RNA cutting. Therefore, there is a proposed link between small RNA biogenesis and RNA splicing, but the underlying mechanism of this cross-talk was not addressed in detail. The main objective of our work is to understand the integration between these machineries and to what extent the convergence of these two post-transcriptional mechanisms determines the final destination of the RNAs and the regulation of gene expression in plants. We performed a screening to evaluate the accumulation of different miRNAs in a series of mutants in splicing-related factors (SRFs). We found four SRFs that affect the production of miRNAs. We hypothethyse that SRF1, SRF2, SRF3 and SRF4 participate in the regulation of  their biogenesis  since genes structure of  many miRNAs affected in those mutants have no introns neither located in introns of other genes. In addition, the overexpression of miRNA172 and miRNA319 that induces early flowering or crinkled leaves, respectively, showed in SRF1, SRF2, SRF3 and SRF4 mutants milder phenotypes compared to wild-type plants. These observations suggest a crosstalk between splicing and miRNA biogenesis that depends on at least four SRFs. In order to decipher the molecular mechanism, we plan to perform CoIP and CLIP-seq assays to determine which microprocessor component(s) or pre-miRNAs interact with the SRFs, respectively.molecular biology, post-transcriptional mechanisms, splicing, miRNAs, Arabidopsis thaliana
Trichoderma LR28 sp. as a potential biocontrol agent against peanut smut caused by Thecaphora frezziiLucio Valetti (1)Posada, G.A. (2), Bustamante, O.M. (3), Sardo, M.F. (1), Suarez, P.A. (3), Espinosa Herlein, M.A. (3), González, N.R. (1), Monteoliva, M.I. (3), Paredes, J.A. (1), Guzzo, M.C. (3)(1) IPAVE-UFYMA, CIAP, INTA-CONICET; (2) FCQ, UNC; (3) IFRGV-UDEA, CIAP, INTA-CONICETThecaphora frezzii is the causal agent of peanut smut, which generates yield losses of up to 50%. Synthetic fungicides produce adverse effects on human health, food safety, and environmental quality. The use of biological commercial products in agriculture is increasing rapidly as an alternative to synthetic pesticides. Trichoderma spp. is the most widely used antagonistic fungus to control fungal diseases. In previous work, we selected the Trichoderma sp. LR28 strain for its antagonistic capacity against T. frezzii in vitro. Therefore, this study aimed to evaluate the antagonistic capacity of Trichoderma sp. LR28 against T. frezzii in vivo and the plant responses in terms of chlorophyll, oxidative stress, and antioxidative response. Peanut seeds were surface-sterilized and germinated at 25 °C for 7 days. Germinated seeds were sown in 8 L pots containing a mixed soil-vermiculite (4:1 v/v). Each pot was inoculated with T. frezzii spore (1x104 teliospores/g of soil). Trichoderma was sprayed with 4 ml of conidia suspension (1x108 conidia/ml) per plant. Suspension was applied at seeding, flowering, pegging, and their combinations. Biochemical responses to Trichoderma were measured as proline, FRAP, and chlorophyll contents. Smut intensity was assessed through incidence (as a percentage of diseased pods out of the total of sampled pods), disease severity index (DSI, using a five-class severity scale for peanut smut), and control efficiency (as a percentage of untreated plants). We observed variability in biochemical responses induced by Trichoderma inoculation. A significant decrease in severity index was observed in plants inoculated with LR28 in seed, flowering, and pegging compared to the untreated control. These results confirmed the biocontrol capacity of Trichoderma sp. LR28 strain and differential induction of biochemical changes remains to be further studied.

Funding INTA 2019-I069, -I516, INTA 2023-I084, -I071, FONCyT PICT STARTUP 2018-0065
Arachis hypogaea; bioinputs; Thecaphora frezzii; Trichoderma; biological control
Constitutive expression of a soybean HD-Zip I transcription factor enhances drought tolerance in ArabidopsisAlfonso Belloni, Y. (1)Gaido, J. (1); Jaime, C. (1); Vegetti, A. (1,2); Dunger, G. (1,2); Dezar, C. (1)(1) Instituto de Ciencias Agropecuarias del Litoral, CONICET-UNL, Argentina. (2) Facultad de Ciencias Agrarias, UNL, Argentina.Drought causes significant crop yield losses worldwide. Despite the significant progress using model transgenic plants, the crop technology available nowadays is not sufficient for farmers for increasing or maintaining soybean yields under low rainfall conditions.

The plant proteins belonging to the transcription factors family HD-Zip I have been proposed as key players in specific plant developmental processes, such as those associated with external stimuli and stresses. We focus here on a Glycine max gene that encodes a transcription factor that has been shown to change its expression in drought conditions. Our findings with this transcription factor introduced into Arabidopsis thaliana reproduce the previously reported phenotypic characteristics observed in Arabidopsis plants transformed with other transcription factors of this family. Compared to the non-transgenic control plants, transgenic plants showed a higher recovery rate after a period of water deprivation, similar water loss, and delayed senescence. Furthermore, we found changes in the expression patterns of genes in Arabidopsis transgenic plants, which would help to elucidate its role in the development of tolerance to environmental stresses.

Based on these results, we propose that this soybean transcription factor could be a useful biotechnological tool to cope with water stress in a wide range of situations, especially in rainfed environments with low yield performance due to drought.
Drought tolerance, Transcription factor, Soybean
Frost tolerance and adventitious rooting in hybrid clones of EucalyptusPaula Gabriela AyalaAyala, P.G. (1); Vivas, V.L. (1); Sansberro, P.A. (2,3); Harrand, L. (1); Margarit, E. (4); Oberschelp, G.P.J. (1)(1) Instituto Nacional de Tecnología Agropecuaria (INTA) Ruta 22 y vías del ferrocarril, CP E3200AQK, Estación Yuquerí, Concordia, Entre Ríos, Argentina; (2) Laboratorio de Biotecnología Aplicada y Genómica Funcional. Instituto de Botánica del Nordeste (CONICET); (3) Facultad de Ciencias Agrarias (UNNE). Sgto. Cabral 2131. W3402BKG, Corrientes, Argentina. (4) Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET). Suipacha 570, Rosario, Santa FeCultivated eucalyptus species are characterized by high productivity. However, the vast majority of tropical and subtropical species are sensitive to frost, and those that are more tolerant are difficult to propagate. Therefore, the development of genotypes with both traits is of great interest for forest breeding. In this work, was evaluated the tolerance to freezing stress and adv. rooting of hybrid genotypes of E. benthamii x E. camaldulensis subsp camaldulensis (BCC) and E. benthamii x E. camaldulensis subsp acuta (BCP), E. benthamii (EB), E. camaldulensis subsp camaldulensis (ECC) and E. camaldulensis subsp acuta (ECP) as parental species, and E. grandis (EG) as a control. Leaf discs of each genotype were sampled and temperature ramps down to -3°C were applied to evaluate the percentage of electrolyte leakage (EL) by freezing. Mini-cuttings were collected from the same plant material, then conditioned and transferred to the rooting module to evaluate rooting after 30 days. Evaluations were made twice, in spring and in autumn. Overall, a lower EL was observed in autumn (25.6% rel. to EG) compared to spring (45.7%), indicating a greater tolerance to cold in autumn due to acclimation. Some hybrid genotypes showed lower EL values in both seasons, indicating a higher basal tolerance to cold. Still, although the rooting of mini-cuttings was similar on average in both seasons, it decreased notably in autumn for EB, and increased for BCC hybrids and EG.  However, rooting was lower in these hybrids than in their E. camaldulensis parents. Apart from the main trends, a large variability in responses was observed among the hybrid genotypes, identifying individuals with high tolerance to frost tolerance and rooting ability. These results suggest the potential of these hybrid combinations. Furthermore, it represents a starting point for metabolomics and proteomics studies, which will help to elucidate the relationship between cold tolerance and adventitious rooting ability.Breeding, cold acclimation, freezing, rooting
Exploring the roles of DPa and DPb Proteins after UV-B exposure in Arabidopsis thaliana plants.Simonelli, Lucio BrunoSheridan, María Luján (1); Casati Paula (2)Centro de Estudios Fotosintéticos y Bioquímicos (CONICET-UNR).Plants are exposed to harmful UV-B radiation, which can damage lipids, proteins, and DNA, leading to inhibited growth and root elongation. The G1/S transition is a critical checkpoint in cell division, regulated by the Retinoblastoma (Rb) protein and E2F transcription factors. Some E2Fs require DP proteins for regulation, while others act independently. Studies on E2F mutants (e2fa, b, and c) revealed diverse responses to UV-B radiation, affecting cell division, DNA repair, and differentiation pathways.

The roles of DPa and DPb in these responses have not been analyzed. Thus, we used simple and double dpa and/or dpb mutants to understand their role in DNA damage accumulation and cell proliferation under UV-B exposure. The mutants showed no significant difference in root development compared to the wild type (WT) under control and UV-B conditions. Confocal microscopy showed that both dpa2 and dpb1 mutants exhibited similar results to the WT line in this zone, while dpa2xdpb1 showed distinct outcomes with a larger meristematic zone with more cells and longer cell length than the WT. This result, compared to the primary root experiment, suggests a potential compensatory effect in the elongation/differentiation zone of the primary root in response to these mutations.

Furthermore, the mutants exhibited a lower number of dead cells after UV-B treatment, indicating the importance of DPa and DPb proteins in regulating Programmed Cell Death. While dpa2 and dpb1 mutants showed no significant difference compared to WT Col-0, dpa2xdpb1 exhibited increased damage. These results suggest that there is functional redundancy between DPa and DPb during DNA repair.

In conclusion, both DPa and DPb participate in UV-B responses in Arabidopsis. Both proteins play redundant roles in DNA damage accumulation, and they are also involved in cell proliferation, plant growth, and programmed cell death in response to UV-B exposure.
Arabidopsis, UV-B radiation, DPa, DPb, Roots
Ecophysiological responses of olive trees to warming in different phenological stages of crop developmentSearles, P.S. (1)Miserere, A. (2); Rousseaux, M.C. (1)(1) Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-Provincia de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET). (2) Centro de Investigación e Innovación Tecnológica (CENIIT), CONICET, Universidad Nacional de la Rioja (UNLaR)Global warming is an important aspect of climate change. Yet, little research on how the vegetative growth and reproductive development of fruit trees will respond to increasing air temperature has been conducted.  For this reason, a long-term research program was initiated in 2014 in northwest Argentina to study the effects of warming on young olive trees (Olea europaea L.).  A series of warming experiments (+4 °C) have been conducted using open top chambers to assess responses during oil accumulation (summer and fall), early vegetative growth and reproductive development (late winter and spring), and chilling accumulation (fall and winter) for flowering.  The results indicate fruit size as well as oil accumulation and its quality are reduced by warming, and that available carbon is preferentially allocated to leaf area.  When warming in the late winter and spring, flowering is much earlier and there are adverse effects on fruit set that appear to be cultivar dependent.  In contrast, shoot elongation is less affected by warming.  The most important responses to warming appear to be related to chilling accumulation in the fall and winter, which is necessary for spring flowering.  Flowering intensity is severely reduced by warming and the flowering period is much longer.  It appears that fruit and oil yields in olive trees will be greatly reduced in northwest Argentina considering the currently available cultivars.  Both adaptation strategies for current cultivars and a search for new cultivars could reduce the impact of warming in the coming decades.flowering, fruit set, fruit size, oil accumulation, open top chambers
Physiological and genetic characterization of wheat lines sharply differing in sodium accumulationSilva, M.M. (1)Moriconi, J.I. (2); Gualano, L.D. (2); Tranquilli, G.E. (1); Santa-María, G.E. (2)(1) Instituto de Recursos Biológicos (IRB), CIRN, INTA, Argentina. (2) Instituto Tecnológico Chascomús (INTECH), CONICET-UNSAM, Argentina.A former Genome Wide Association study allowed us to identify T. aestivum genomic regions involved in setting high sodium (Na) accumulation at the seedling stage under conditions of low potassium (K) supply. In this work we firstly ranked the lines examined and selected three of high and three of low Na accumulation. We next evaluated the pattern of growth, Na and K accumulation in those lines when grown at either optimal or limiting levels of K supply and then attempted to advance towards the validation of candidate regions through a biparental population approach, using contrasting genotypes for Na to derive F2 families.
We observed differences in Na accumulation among genotypes in the aerial plant fractions, which were considerably increased under limiting K supply. Interestingly, genotypic differences in Na accumulation, which were found to involve differences in Na uptake and translocation, were companied by genotypic differences in Potassium Utilization Efficiency (KUtE), thus suggesting the suitability of Na accumulation based approaches to improve KUtE. Interestingly, differences in KUtE were not necessarily associated to differences in tolerance to low K supply, thus indicating that, at least for the lines examined, the positive influence of Na does not equally impact on all the desired agronomic traits at the vegetative stage.
Next, we used two sets of biparental lines. Non-destructive phenotyping of 87 and 89 F2 individuals, grown at low K supply, was companied by genotyping through two 1BL region-flanking SSR markers for each family, as far as the 1BL chromosome region may account for ~25% of the total variation in Na accumulation. A bimodal frequency distribution of both F2s was observed suggesting a dominant Mendelian distribution for the trait. All evaluated SSR showed a significant cosegregation with [Na] for both F2 families. These data confirm region 1BL as a strong candidate for the major differences found in Na accumulation at low K supply.
wheat, Triticum aestivum, genetics, potassium, sodium, utilization
The foliar application of Bacillus sp. CHEP5 protects peanut plants against phytopathogens by inducing systemic resistanceMaría Soledad FigueredoFigueredo MS (1), Tonelli, ML. (2), Loser U. (2), Fabra A. (2).(1) Facultad de Ciencias exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto. (2) Instituto de Investigaciones Agrobiotecnológicas (CONICET-UNRC).Diseases caused by fungi represent an important limitation in peanut production in Córdoba, Argentina. In order to revert this problem, producers apply synthetic fungicides more than once during the crop cycle. However, the incidence of fungal diseases, especially of the rhizoplane, is still causing significant economic losses in peanut cultivation. Among them are wilt and peanut smut caused by Sclerotium rolfsii and Thecaphora frezii, respectively. Previous works of our laboratory demonstrated that the native biocontrol strain, Bacillus sp. CHEP5, induces systemic resistance in peanut plants against the phytopathogens S. rolfsii and T. frezii when is inoculated in root or seed. The objective of this work was to evaluate the ability of Bacillus sp. CHEP5 to induce systemic resistance when applied by foliar spray on peanut, both in assays done under controlled conditions and in the field. Quantification of soluble phenolic compounds was used as a defensive response marker. Plants growing under controlled conditions and inoculated with Bacillus sp. CHEP5 (4 L ha-1) in leaves showed a reduction (88%) in the incidence of the wilt caused by S. rolfsii. In addition, it was observed an increase in their aerial and root dry weight (80% and 44%, respectively). On the other hands, an increment of soluble phenolic compounds, was found at 48 hours post pathogen inoculation. Under field conditions, only peanut smut was detected. Our assay revealed a reduction in the incidence and severity of this disease (32% and 33% respectively) when Bacillus sp. CHEP5 (4 L ha-1) was applied by foliar spray at 70 days post-sowing. In addition, an increment in yield around of 11 % was observed in plots treated with biocontrol strain respect to control plots. Our results demonstrate that the native biocontrol strain, Bacillus sp. CHEP5, protects peanut plants against phytopathogens S. rolfsii and T. frezii by inducing systemic resistance when is inoculated by foliar spray.

biocontrol, induced systemic resistance, Bacillus sp., peanut
Photochemical efficiency of sugarcane (Saccharum spp.) in response to low radiationCepeda, A.M (1)Quevedo, Y.M. (1) ; Mejía De Tafur, M.S (2)Centro de investigación de la caña de azúcar de Colombia, CENICAÑA, Colombia. (2) Universidad Nacional de Colombia sede Palmira, Colombia..Sugarcane crop contributes to the global economy through the extraction of sugar and by-products. Solar radiation (SR) is energy source for photosynthesis. However, fluctuations in SR intensity can influence the photochemical efficiency and the crop’s yield potential. The objective of this research was to evaluate the effect of low SR on the photochemical efficiency of two contrasting sugarcane varieties during the ripening phase in Colombia. Shadow mesh was installed over the crop and three SR reduction treatments (67%, 80%, and 95%) were evaluated and an open-field control (0%). Chlorophyll fluorescence and OJIP curves were measured using an integrated gas exchange system with a fluorometer. No differences among the evaluated varieties were found. The low SR treatments (67, 80, and 95%) did not differ from each other but did differ from the control (0%). The low SR did not affect Fv/Fm, but it reduced NPQ (12%), ETR (19.5%), and Φ PSII (19.4%). Fi and Fp steps of the OJIP curve were the most sensitive, showing higher fluorescence emission. Fv increased (12%), and Vj decreased (10%). Specific energy fluxes ABS/RC, Dio/RC, Eto/RC, and Tro/RC, as well as quantum efficiencies ϕPo and ϕDo, were not significant in the study. ϕEo (15%) decreased, while Ψo (10%) and vital indices PI (25%) and DF (18%) increased. Therefore, it was determined that low SR did not affect light absorption by the light-harvesting antennas and P680, nor the electron transfer from P680* to QA-. It is hypothesized that low SR caused a reduction in the redox potential of PSII, affecting the oxidation of QA- and reducing the electron flow to QB+. Accumulation of QA- molecules led to a blockage, resulting in reduced ETR, increased fluorescence emission, and decreased ΦPSII. These alterations in the photochemical reactions of PSII may reduce photosynthesis rates and result in yield loss during the ripening phase of sugarcane.C4 photosynthesis, OJIP transients, shade, chlorophyll fluorescence, electron transport.
Phenotypic characterization of a flower mutation in the grapevine cultivar Listán Prieto and its effects on productivityTomás OroñoOroño, T. (1); Muñoz, C. (1); López, M. (1); Gómez Talquenca, S. (2); Torres, R. (2); Lijavetzky, D. (2); Calderón, L. (2)(1) Instituto de Biología Agrícola de Mendoza (IBAM, CONICET-UNCuyo), Chacras de Coria, Mendoza, Argentina. (2) Plant Virology Laboratory, EEA Mendoza INTA, Luján de Cuyo, Mendoza, Argentina.The first hermaphrodite flowers appeared in grapevine (Vitis vinifera L.) because of the domestication process. This is a main characteristic of cultivated grapevines differing from their wild dioecious ancestors. Due to the predominant presence of masculinized flowers, accession Criolla Chica Nº2 (CCN2) is catalogued as a flower mutation of Criolla Chica (Argentinian synonym for cv. Listán Prieto -LP-). As the initial step of the molecular characterization of CCN2 mutant, the present study aimed to analyze the impact of the mutation on different reproductive and berry-related traits. The evaluated traits were fertility, yield, biochemical berries composition, seeds number and morphology. As control genotype we analyzed the accession Criolla Chica “Ballista”, with hermaphrodite flowers. Both LP genotypes are planted in the same vineyard, at the “Colección de Uvas Criollas” (EEA INTA-Mendoza). The mutant CCN2 presented abscission of most inflorescences (averaging 65%), due to a strong fruit-set reduction. This phenomenon was not observed in CCBA. Regarding yield components (clusters/plant, berries/cluster, berry weight and seeds/berry), CCN2 exhibited lower values than CCBA (p<0.001). This reduction severely affected the average yield/plant, with 5 kg in CCBA and 0.3 kg in CCN2. The soluble solids concentration was one degree Brix superior in CCBA, whereas CCN2 presented a higher concentration of total polyphenols and total anthocyanins (ca. 30%). Additionally, the seeds of CCN2 showed notorious shape and size alterations. In conclusion, the studied flower mutation negatively affected fertility and productive traits of CCN2. Simultaneously, it seems to have affected the biochemical composition of berries and could be responsible of seed morphology alterations.flower mutation, grapevine, fertility, yield, seeds morphology
Postharvest UV-B treatment in strawberry fruit (Fragaria x ananassa): effects on the signalling pathway and secondary metabolites biosynthesis.Antonella Barriga LourencoCasajus, V. (1,2); Martínez, G. (1,3); Civello, M. (1,3)(1) Instituto de Fisiología Vegetal, UNLP – CONICET, Argentina. (2) Facultad de Ciencias Agrarias y Forestales, UNLP, Argentina. (3) Facultad de Ciencias Exactas, UNLP, Argentina.Strawberry fruit has a high content of vitamins, flavonoids and phytosterols and it is considered a functional food for these benefits on human health. UV-B postharvest treatments extend strawberry fruit shelf life and increase the content of antioxidants compounds as phenols and flavonoids. The proposed UV-B signalling model in A. thaliana involves a dimeric receptor UVR8 and two key proteins -CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) and the ELONGATED HYPOCOTYL5 (HY5) transcription factor- that regulates many UVR8 target genes as those related to phenols, flavonoids, and anthocyanins biosynthesis. The goal of this work was to evaluate the effect of UV-B irradiation on the content of antioxidant compounds and the UV-B signalling and phenylpropanoids biosynthesis pathways. Strawberry fruits were harvested, immediately irradiated with 5 Kj/m2- 18,8 W/m2 or 6 Kj/m2- 9,7 W/m2 and stored at 20 °C in darkness for 2 days. Total phenols, flavonoids and anthocyanins contents were determined, and the expression of genes related to the signalling pathway was evaluated by qRT-PCR. Results showed higher phenolic and flavonoid contents in irradiated fruits. As early as 3 h after UV-B treatments we noticed a higher UVR8 gene expression, and this trend was kept during the postharvest storage. A similar gene expression pattern was found for the transcription factor HY5, reaching a 2-fold higher expression level than controls after 48 h of storage. In general, the expression of COP1 was not significantly affected by UV-B treatments. Therefore, the expression of phenylpropanoid biosynthetic pathway genes (PAL1, phenylalanine ammonia lyase; F3H, flavanone 3-hydroxylase; and ANS, anthocyanidin synthase) would be induced by UV-B radiation; meanwhile CHS (chalcone synthase) expression was not affected by these treatments. This work suggests that the effects of UV-B treatment in strawberry fruits are mediated by the UVR8 signalling pathway.molecular biology, strawberry, UV-B, secondary metabolism.
Plant growth-regulating hormonal pathways are targeted by two effectors belonging to evolutionary unrelated filamentous pathogens.BOGINO, M.F.LAPEGNA SENZ, J. M. * ; BOGINO, M.F. * ; FABRO, G. (* Co-autores)Centro de investigaciones en Química Biológica de Córdoba (CIQUIBIC-CONICET). Departamento de Química Biológica "Ranwel Caputto", Facultad de Ciencias Químicas (DQB-FCQ). Universidad Nacional de Córdoba.Plant pathogens evolved several ways to colonize their hosts. Proteinaceous effectors are part of the weaponry they deploy to subvert plant defenses. Filamentous pathogens release effectors into the apoplast or the cytoplasm of plant cells, where they interfere with multiple host’s metabolisms.

Interactomics’ experiments reported that effector OEC115 from the fungus Golovinomyces orontii interacts with two Arabidopsis’ proteins, BIM1 and IAA11, which participate from the Brassinosteroids and Auxins signaling pathways, respectively. Many reports describe the involvement of these hormones in defense responses; however, the specific functions of BIM1 and IAA11 in plant immunity remain unclear. Interestingly, we previously found another effector, HaRxL106 from the oomycete pathogen Hyaloperonospora arabidopsidis, that also interacts with BIM1 and IAA11.

Here we confirmed the interaction of OEC115 with BIM1 and IAA11 by Yeast-two-Hybrid (Y2H) and Bimolecular Fluorescence Complementation (BiFC) assays. Both effectors, as well as their targets, localize in the nucleus of plant cells. Surprisingly, OEC115 and HaRxL106 have no similarities in their aminoacidic sequence, suggesting that their activities over BIM1 and IAA11 could be different. Indeed, when we developed infection assays on 35S:GFP-OEC115 overexpressing plants with Pseudomonas syringae pv. tomato,  we observed that, unlike HaRxL106 overexpressors, these plants were not more susceptible than the wild type. Moreover, 35S:GFP-OEC115 plants do not present visible abnormal developmental phenotypes, as plants expressing HaRxL106 do.

The evolutionary convergence of these effectors towards the same host proteins is intriguing, given that these two non-related pathogens manipulate the same “targets” but with different phenotypic outputs. We present our perspectives to further investigate these effectors’ molecular mechanisms to tamper plant defenses and/or growth.


Effectors, Immunity, Oomycetes, Fungi, Brassinosteroids, Auxins
Understanding root growth: more complex than anticipatedCrisanto GutierrezBénédicte DesvoyesCentro de Biologia Molecular Severo Ochoa, CSIC-UAM, Madrid, SpainThe transition to multicellularity required the evolution of novel structures and mechanisms to coordinate cell division, acquisition of cell fates and the establishment of complex regulatory networks. Organogenesis relies on the production of new cells together with the formation of organ domains and cell types directed by patterning genes. A fundamental question in cellular and developmental biology is to understand the coordination between cell patterning cues and cell division. The mechanisms linking the local activity of stem cell regulators with the cell cycle machinery and the control of division of stem cells and their derivatives remain largely unknown. We focus our studies on the Arabidopsis thaliana root as a model to understand how cell proliferation, transcriptional regulation, genome replication and epigenetic information are coordinated during root development. I will describe recent results in this line and discuss the complexity in understanding root growth where we are identifying the multiple layers of control.Cell cycle, stem cell, transcription factor, root development, root apical meristem, Arabidopsis, plant
Yield strategies under contrasting water conditions in winter cerealsBarnada, F.J.Miralles, D.J. (2, 3); Diez, M.M. (2); Alvarez Prado, S. (1, 3, 4)(1) Cátedra de Sistemas de Cultivos Extensivos-GIMUCE, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Provincia de Santa Fe, Argentina. (2) Departamento de Producción Vegetal, Cátedra de Cerealicultura, Universidad de Buenos Aires y CONICET, Buenos Aires. (3) IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Argentina. (4) IICAR – CONICET, Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla, Provincia de Santa Fe, Argentinaver resumen adjuntowinter cereals, water deficit, grain yield, main stem, tillers.
Mejoramiento Molecular de la Alfalfa mediante CRISPR/Cas9Gabriela Cynthia SotoGalindo Sotomonte, L; Stritzler, M; Gómez MC; Bottero A; Jozefkowicz C.; Ortiz, A; Pascuan, C.; Frare, R.; Blumwald E; Ayub NIGEAF grupo vinculado a IABIMO, CONICET INTA, ArgentinaLa alfalfa es la principal forrajera de Argentina y, en términos de área sembrada, es el segundo cultivo más importante en nuestro país. Se trata de una especie leguminosa perenne, lo cual la convierte en un cultivo fundamental en las rotaciones agrícolas debido a su capacidad para fijar nitrógeno y en una forrajera de destacada calidad nutricional. Su amplia variabilidad genética le confiere la capacidad de adaptarse a diversas regiones.


Durante varias décadas, el INTA ha llevado a cabo un exitoso programa de mejoramiento genético de la alfalfa. Nuestro equipo de investigación ha desempeñado un rol activo en este programa, estudiando genes de interés agropecuario y utilizando herramientas biotecnológicas para introducir variabilidad en aquellos caracteres en los que su gran variabilidad natural resulta insuficiente.


En esta presentación, compartiremos los avances alcanzados en los últimos años en el mejoramiento molecular de la alfalfa mediante la revolucionaria tecnología de edición génica CRISPR/Cas9. Conversaremos sobre nuevos genes en estudio, enfocándonos en el control de la floración y la calidad del forraje.
crispr/cas9; alfalfa; mejoramiento; calidad; genética
Biological nitrogen fixation in maize: a comparative exploratory analysis with soybean.Carlos Fabián PiccinettinoneLaboratorio de Bacterias Promotoras del Crecimiento Vegetal-IMYZA- INTA CastelarThe soybean, like maize, is a crop of great economic and nutritional importance worldwide. Although the significance of biological nitrogen fixation (BNF) through symbiosis is already acknowledged in soybean, the potential of associative BNF in maize is only beginning to be explored. The aim of this study was to conduct a theoretical and exploratory analysis of the potential BNF contribution that a maize plant should have to match that of a soybean plant. The evaluation was carried out on plots of a rotation trial during one cycle (2012/2013) with 6 replicates per crop. The amount of N uptake per plant and the contribution of BNF in soybean were determined. Subsequently, an estimation of the potential BNF-derived N in maize to equal that of soybean was performed. For soybean, the results were as follows: grain yield (GY): 2.8 Mg/ha; N uptake in aerial biomass: 198 kg N/ha; N in grain: 5.54%; N export in grain: 155 kg/ha (78%); N uptake/pl: 792 mg N with an average density of 250,000 plants/ha; %BNF: 68%; the BNF-derived N: 135 kg N/ha; the BNF-derived N/pl: 542 mg N, and an N uptake/GY ratio of 71.3 kg N/Mg grain. For maize, the results were as follows: GY: 8.7 Mg/ha; N in grain: 1.12%; N export in grain: 97 kg/ha (56%); N uptake in aerial biomass: 174 kg N/ha; N uptake/pl: 2175 mg N with 80,000 plants/ha, and an N uptake/GY ratio of 20.0 kg N/Mg grain. Therefore, to match soybean in %BNF, maize should fix 118 kg N/ha; 1479 mg N/pl, but the balance between uptake and export should fix 1218 mg N/pl. For a determination with current field methods, i.e., 20% or more %BNF, the minimum diazotrophic N-fixing, maize crop should fix 35 kg N/ha and 435 mg N/pl. The challenge is to increase BNF rates through genetic improvement and/or the interaction of more efficient diazotrophic microorganisms. Simultaneously, the development of methods more sensitive than the current ones, and adapted to the field, is essential to accurately determine the real BNF contribution in maize.Biological Nitrogen Fixation, Maize, Soybean, Genetic improvement, Diazotrophic microorganisms
Azospirillum argentinense biofilm: implication of polyaminesSilvana Díaz HerreraZawoznik, M.S. (1); Benavides M.P. (1); Groppa M.D.(1)(1) Cátedra de Química Biológica Vegetal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113) Buenos Aires, Argentina.Among plant growth-promoting rhizobacteria (PGPR), Azospirillum argentinense Az39 is a reference strain for inoculants in Argentina, and the study of its interaction with plants has raised great interest . Despite its importance and widespread use, studies on the molecular traits involved in plant colonization are lacking. Since biofilm formation is one of the first steps in root colonization and considering that polyamines are involved in numerous physiological processes in both plants and bacteria, we aimed to study polyamine´s role in this process.
Biofilm formation was quantified by crystal violet staining in 96-well plates, where the target microorganism was cultured for 3 days at 30 °C in the presence of three different concentrations of the polyamines putrescine, spermidine, spermine, and cadaverine separately. The effect of the putrescine biosynthesis inhibitors DL-α-difluoromethyl arginine (DFMA) and DL-α-difluoromethyl ornithine (DFMO), and the spermidine and spermine inhibitor cyclohexylamine (CHA), was also studied. All treatments were compared to controls without polyamines or inhibitors.
The addition of the 4 polyamines inhibited biofilm formation in a dose-dependent manner, except for the 0.5 mM Spd concentration. Polyamine biosynthesis inhibitors led to an increased biofilm formation. The results obtained so far allow us to conclude that polyamines are involved in biofilm formation by Azospirillum argentinense Az39.
Azospirillum, biofilm, polyamines
Different strategies to optimize the inoculation of potato plants with Methylobacterium sp. 2AMartinez-Moyano, Edgar (1)Grossi, C.E.M (1); Gitman, I.F.B (1); Ulloa, R. (1,2)(1) Instituto de Investigaciones en Ingeniería Genética y Biología Molecular “Dr. Héctor N. Torres” INGEBI-CONICET, CABA, Argentina. (2) FCEyN-DQB-UBA, CABA, Argentina.A plant growth-promoting rhizobacteria (PGPR) belonging to the genus Methylobacterium was isolated from roots of potato plants. This PGPR, named Methylobacterium sp. 2A, enhanced the growth of Arabidopsis and potato in vitro plants exposed to salt conditions, antagonized plant pathogens and reduced disease symptoms in potato plants infected with Phytophthora infestans (Grossi et al 2020). We aim to understand if the inoculation of Methylobacterium sp. 2A enhances plant defense in potato plants through an induced systemic resistance (ISR) or by direct antagonism with the pathogen. To this end, we employed three inoculation strategies using a suspension of Methylobacterium sp. 2A cells (0.05 OD600 units in 0.85% NaCl) or only 0.85% NaCl (control): i) roots of plants grown in solid MS for 3 weeks were inoculated with 100 µl of the suspension. Inoculated plants and controls were multiplied three consecutive times using internodes from the upper portion of the plants and the presence of Methylobacterium was checked; ii) plants grown in solid MS for 3 weeks were transferred to liquid MS for 24 h and then roots were inoculated with 0.8 ml of the suspension and harvested at 3-, 10-, and 13-days post inoculation (dpi). The presence of Methylobacterium in the liquid media was checked; iii) plants grown in solid MS for 3 weeks were transferred to liquid MS for 24 h and then inoculated with 0.8 ml of the suspension. At 8 dpi, plants were transferred to pots and placed in the greenhouse. Two weeks later, Methylobacterium was recovered from a leaf extract of inoculated plants and plant growth was evaluated in each condition. Plants had a better fitness in hydroponics and the growth promotion was evident in inoculated plants. P. infestans infection assays will be conducted on plants inoculated using the three different strategies to evaluate ISR.

plant growth-promoting rhizobacteria, Methylobacterium sp. 2A, Phytophthora infestans, Solanum tuberosum
Dynamic expression of Kunitz protease inhibitors (KPI) in potato plants, sprouts and tubers exposed to light/dark conditions. Cloning of StKPI3.18520.Gitman, Iván Federico Berco (1)Ulloa, Rita María (1, 2)(1)Instituto de Investigaciones en Biología Molecular e Ingeniería Genética “Dr. Héctor N. Torres” INGEBI-CONICET, CABA, Argentina. (2) FCEyN-DQB-UBA, CABA, Argentina.During sprouting, proteases break down the tuber storage proteins to provide free amino acids and small peptides which can contribute to the synthesis of structural and functional proteins of the developing sprout. Under continuous dark conditions plants are unable to obtain their resources from photosynthesis and undergo an autophagic process. During senescence, cellular components are degraded and remobilized to other parts of the plant. Plant proteolysis is the result of an interplay between plant proteases and protease inhibitors. We identified 142 protease inhibitors in the potato genome, 18 are clustered in tandem in chromosome 3 at 43 Mbp. According to public RNAseq data we observed that three of them, KPI 3.43.18520, KPI3.43.18580 and KPI3.43.18600, are upregulated in plants exposed to different stress treatments. RT-qPCR assays performed with specific primers against these genes showed that KPI3.43.18520 had the highest expression. Its expression pattern was further evaluated in dormant or sprouting tubers, in sprouts or in in vitro plants grown under 16:8 h photoperiod or under continuous darkness using degenerate primers that amplify a common region shared by KPI3.43.18580 and other closely related KPIs. We observed that KPI transcripts were high in dormant tubers, decreasing ≈ 4-fold in sprouting tubers, while increasing in the young sprout grown in the light. However, if the sprout was kept under dark conditions for long periods, we observed higher levels of expression. On the other hand, KPI transcripts were higher in plants grown under 16:8 photoperiod compared to those grown in the darkness. Overall, these data suggest that the expression of KPIs responds to the different nutritional requirements. To further understand the role of KPI3.18520 we cloned is coding region downstream to 35S promoter in pBI121 to obtain transgenic overexpressing plants.Protease inhibitors, Solanum tuberosum, tuber sprouting, darkness induced senescence, RT-qPCR
Chia (Salvia hispanica L.) yield is limited by sink strength during grain fillingAcreche, M.M. (1, 2)Burgos, S. (3); Diez, J. (1, 3)(1) Estación Experimental Agropecuaria Salta, INTA. (2) Centro Científico Tecnológico Salta Jujuy, CONICET. (3) Facultad de Ciencias Naturales, UNSa.Chia is a summer annual herbaceous plant. Its grains are gluten-free, have a 29-35% oil content, and are very rich in omega-3 and omega-6 fatty acids. These characteristics generate interest among growers, industries, and consumers. However, there is scarce information about the yield formation process. The main yield components are the number of grains ha-1 and the number of grains verticillaster-1, with the number of grains ha-1 being the most important component that defines the critical period for yield. Moreover, the two commercial populations used by growers (white chia, W; black chia, B) differed in average grain weight, with W having higher average grain weight than B. However, the yield response to changes in resource availability during grain filling is still unknown. We conducted an experiment with the two populations in the Valle de Lerma, Salta. At the end of the critical period (7 days after the end of flowering), 10 uniform (in size and phenology) plants were selected in each experimental unit, and in 5 of them, the source-sink ratios were modified by hand-trimming of 50% of the sinks (removing the inflorescences longitudinally from one side in the main verticillasters and in the apical half in first-order verticillasters). At harvest, the main verticillaster was divided into 3 sections (apex, middle, and base). Regardless of the population, increasing the availability of assimilates per growing grain by 100% increased the average grain weight by 6 to 10% in the three sections evaluated in the main verticillasters. In the first-order verticillasters, B increased average grain weight by 11%, while W showed no change in average grain weight. Although there were no significant differences, the photosynthetic rate of plants with reduced sink was slightly lower than that of the controls. These results revealed that chia is mainly limited by sink strength during grain filling.Ecophysiology, Chia, Source-sink ratio, Average grain weight, Grain filling
Functional Implications of Tudor-SN (TSN) and PRMT5 in the regulation of arginine methylation in ArabidopsisM. Clara FontanaFontana, M.C. (1); Agrofoglio Y. (1); Torres S. (1); Née G. (2); Iglesias M.J. (1); Mateos J.L. (1)(1) Instituto de Fisiología, Biología Molecular y Neurociencias (UBA - CONICET), Argentina. (2) University of Münster, Germany.Plants adapt to constant environmental changes by fine tuning their growth and developmental programs through rapid and versatile gene expression regulation. This regulatory mechanism involves posttranslational modifications, including arginine (R) methylation catalyzed by the PROTEIN ARGININE-METHYLTRANSFERases (PRMTs) family. In Arabidopsis PRMT5 constitutes the major symmetric Rs methyltransferase and is involved in light and stress-related developmental responses. However, the proteins that "interpret" these post-translational modifications and their functionality have not been described in plants. In animals, Tudor-SN proteins have been proposed as “readers” of methylated targets of PRMT5. The Arabidopsis genome encodes two genes with both distinctive domains: TSN1 and TSN2. In the current study, we could identify new TSN2 interactors by proteomic experiments, several of which are known to be regulated by PRMT5. In addition, we performed physiological experiments with tsn1 and tsn2 mutants in order to study the role of TSNs in light-regulated processes such as flowering, hypocotyl elongation and circadian behavior, all affected in prmt5. Our results show new functional implications for TSN1 and TSN2 proteins in Arabidopsis, and suggest that both -PRMT5 as a “writer” and TSNs as “readers”- are involved in the regulation of symmetric R methylation in plants.Arabidopsis, posttranslational modifications, arginine methylation, physiological responses
Transcriptome analysis give insights into the role of miR394 in the regulation of flowering genes in Arabidopsis thalianaBelen, F. (1)Bernardi, Y. (1), Rosli, H. (2), Pombo, M. (2), Vegetti, A. (1), Dotto, M. (1)(1) ICIAGRO Litoral (CONICET-UNL), Facultad de Ciencias Agrarias (UNL), Esperanza, Argentina, (2) INFIVE (CONICET-UNLP), La Plata, ArgentinaUnderstanding the intricate regulatory pathways governing plant development and flowering is essential for crop improvement and adaptation to changing environments. In this study, we investigated the role of microRNA miR394 in Arabidopsis thaliana by characterizing mir394a/mir394b double mutant plants. To explore transcriptomic changes associated with decreased expression of miR394, RNA-seq analysis was performed on 14-days-old wild-type (Col-0) and mir394a/mir394b double mutant plants. A total of 3826 differentially expressed genes (DEGs) were identified between the two genotypes. Closer examination of these DEGs revealed a significant impact on flowering-related genes. Notably, key genes involved in the establishment of inflorescence meristem and floral organ identity, including SOC1, FUL, AP1, AP3, AG, SEP3 and PI, exhibited increased expression in mir394a/mir394b double mutants plants, indicating that miR394 plays a key role in regulating the expression of flowering-related genes, influencing flowering time in Arabidopsis. These results are in line with those obtained by our group in previous studies, which highlighted that mir394a/mir394b double mutants displayed an early flowering phenotype. To gain insight into the spatiotemporal expression pattern of MIR394A and MIR394B genes, transgenic pMIR394A::GUS and pMIR394B::GUS Arabidopsis lines were generated. Our analysis revealed that both genes are expressed in diverse tissues, organs and developmental stages, including shoot apical meristem, leaf primordia, ovules and anthers, among others. These results highlight the dynamic and multifaceted expression pattern of MIR394A and MIR394B during plant growth and development, in accordance with several reports showing miR394 involvement in various processes. Overall, our findings contribute to the understanding of the regulatory network of miR394, controlling various aspects of plant development, shedding light on the regulation of flowering time in particular.Plant Development, miR394, Flowering Time, RNA-seq Analysis
Bacillus amyloliquefaciens strain PTA-4838 associated with organomineral fertilizer improves CO2 assimilation rate and light saturation point of maizeMarcelo de Almeida SilvaSilva, M.A. (1); Silva, K.P.O.M. (1); Santos, H.L. (1); Ferreira, L.S. (1); Cassemiro P.F. (1); Carnietto, M.R.A. (1); Modenese, J.F. (1)1Laboratory of Ecophysiology Applied to Agriculture – LECA, School of Agricultural Sciences, Sao Paulo State University - UNESP, Botucatu, SP, Brazil.Maize (Zea mays L.) is the second largest crop produced in Brazil, and the search for technologies that promote increased productivity through improvements in physiological parameters is growing. Therefore, this research aimed to evaluate the effect of a plant growth-promoting bacteria (PGPB) (B. amyloliquefaciens strain PTA-4838 – equivalent to 6.1 × 1010 CFU mL-1) and an organomineral fertilizer (OF) based on organic carbon, macro– and micronutrients, applied in seed treatment, on the response of A (net CO2 assimilation rate) to photosynthetic photon flux density (PPFD) (A/PPFD curves). The experiment was conducted in a greenhouse, in a completely randomized design, with three product applications – control, PGPB, PGPB + OF – and four replicates. All treatments received standard seed treatment (Chlorantraniliprole + Clothianidin). The A/PPFD curves were evaluated through an infrared gas analyzer (LICOR LI-6400XT, Lincoln, NE, USA), using 400 ppm of CO2, ambient temperature and relative humidity, and 18 light pulses (from 0 to 2600 µmol m−2 s−1). They were fitting using the model of Abe et al. (2009). Measurements were performed on the third fully developed leaf from the apex at the V8 growth stage. PGPB provided increases of 3.7%, 13.5%, and 3.5% in the maximum gross photosynthesis rate (Amax), light saturation point equal to 95% (Isat-95), and light-saturated net CO2 uptake [A(Imax)], respectively, compared to the control. PGPB also decreased the dark respiration rate (RD) and the light compensation point (Icomp) by 25% and 18.4%. PGPB + OF provided increases of 9.0%, 13.9%, and 12.9% in the Amax, Isat-95, and A(Imax), respectively, and decreased the RD and the Icomp by 50% and 46.9%, respectively, compared to the control. Thus, it is concluded that photosynthesis and growth of maize treated with PGPB and PGPB + OF will be limited at higher light intensities, which may be favorable under adverse environmental conditions.


"Ver resumen adjunto"
Zea mays L., plant growth-promoting bacteria, biostimulants, CO2 assimilation rate, A/PPFD curves.
Graphene oxide or Bacillus subtilis with Bacillus licheniformis attenuates the drought stress of sugarcane through improving gas exchangeHariane Luiz SantosSantos, H.L. (1); Silva, K.P.O.M. (1); Carnietto, M.R.A. (1); Silva, M.A. (1)(1) Laboratory of Ecophysiology Applied to Agriculture – LECA, School of Agricultural Sciences, Sao Paulo State University – UNESP, Brazil.Water scarcity is the main limiting factor to sugarcane productivity. Thus, technologies influencing plant growth are essential to ensure increased crop yield. Therefore, this research aimed to evaluate the effect of plant growth-promoting bacteria (PGPB) (B. subtilis FMCH002 + B. licheniformis FMCH001 – both equivalent to 1 × 1011 CFU g-1) and graphene oxide (GO), inoculated into buds at the planting, on the gas exchange parameters under water deficiency. The experiment was conducted in a greenhouse, in a completely randomized design 4 × 2 factorial scheme, with four product applications (control – without product, PGPB, GO, PGPB + GO), and two water regimes [water deficiency (–W) – 40% of field capacity and well-watered (+W) – 100% of field capacity] with four replicates. Net CO2 assimilation rate (A), stomatal water conductance (gs), internal carbon concentration (Ci), transpiratory rate (E), water use efficiency (WUE), and carboxylation efficiency (CE) were evaluated through an infrared gas analyzer before water deficiency (95 days after planting – DAP), during water deficiency (109 DAP), and after rehydration (123 DAP). Data were subjected to analysis of variance and subsequent comparison of means using Tukey’s test (p ≤ 0.05). At 95 DAP, PGPB + GO and GO provided increases of 20.5% and 12.0% in gs and CE, respectively, compared to the other treatments. At 109 DAP, GO provided 30.7% and 28.9% more A and CE, respectively, compared to control under –W. In contrast, PGPB decreased E by 32.8% and increased Ci by 46.8% compared to control under –W. At 123 DAP, PGPB provided increases of 33.5%, 40.9%, 21.3%, and 8.4% in A, gs, Ci, and CE, respectively, and GO provided 32.8%, 54.4%, and 30.3% more A, gs, and Ci, respectively, compared to control under –W. Thus, it is concluded that PGPB or GO improved the photosynthetic parameters of sugarcane both under drought and well-watered conditions. However, the combined effect (PGPB + GO) was less efficient.Saccharum spp., plant growth-promoting bacteria, nanoparticle, CO2 assimilation rate, carboxylation efficiency
The RdDM pathway regulates root hair growth and development under moderate salt stress in Arabidopsis thaliana.Cruz Ferrer VieyraCruz Ferrer Vieyra (1,2), Gabriela Auge (1,2)(1) Consejo Nacional de Investigaciones Técnicas y Científicas (CONICET), Argentina. (2) Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Argentina.Plants gather information that enables them to adjust their growth and development to changing environmental conditions by regulating gene-expression and modifying the methylome. Roots are one of the main sensory organs of plants, detecting nutrient and water availability, and directing morphological changes to ensure their uptake. The RNA-directed DNA methylation (RdDM) pathway constitutes a means for establishing epigenetic modifications by altering the expression of target genes. When the plant requires a strategic transcriptome adjustment, this mechanism ensures the transgenerational persistence of epigenetic marks, as well as establishing de novo methylation. To unveil the significance of RdDM in root hair development in Arabidopsis thaliana, we conducted a phenotypic analysis of root traits in null mutant genotypes of RdDM genes in the Columbia-0 background. We did not find significant differences between 2-week old mutant and wildtype plants for root hair density and length in control conditions (MS medium and long days), suggesting that the RdDM pathway may not affect these traits. However, characterization of root development for these genotypes in darkness indicates that methylome homeostasis is linked to the proper regulation of root hair development and growth. In addition, we observed reduced sensitivity (longer and more numerous root hairs) to low salt concentrations (10mM NaCl) for most mutants in comparison with Col-0, which points towards an active role for RdDM in mediating adaptive responses to moderate salt stress. Overall, our results show that the RdDM pathway bestows plants with additional developmental plasticity at the root level, specifically under moderate salt stress and darkness. This insight could highlight RdDM as a possible target for future breeding programs interested in improving plant resilience and tolerance under substandard light and salt conditions.Root hairs, Salt stress, RdDM
Chlorophyll retention and low oxygen consumption rates in soybean seeds produced under heat-drought stressMartinez, Mailen Ariela (1)Montechiarini, N.H. (1); Gosparini, C.O. (1, 2), Oppedijk, B. (4), van Duijn, B. (3, 4)(1) Universidad Nacional de Rosario, Facultad de Ciencias Agrarias, Fisiología Vegetal, Zavalla, Argentina (2) Instituto de Investigaciones en Ciencias Agrarias de Rosario, Facultad de Ciencias Agrarias, Zavalla, Argentina (3) Institute of Biology Leiden, Leiden University, Leiden, The Netherlands (4) Fytagoras B.V., Leiden, The NetherlandsHeat-drought stress (HDS) during the late-developing (R6-R7) soybean seeds (Glycine max (L) Merr.) affects the chlorophyll degradation, resulting in green seeds (G) with low physiological quality. In the research we aim to relate the chlorophyll content, the oxygen consumption with germination and viability of G. Soybean seeds, cv. SRM 3410, produced under controlled conditions of HDS, were classified according to visible chlorophyll retention into G and yellow (Y). Non-stressed seeds were used as control (C). A non-destructive method was used to measure the individual chlorophyll fluorescence (CF) in seeds with pulsed blue LED light. Thirty G, Y and C each were placed on agar (0.4% w/v) into individual 5 ml screw-capped tubes containing an oxygen-sensitive fluorescent coating. The individual seed oxygen (O2) consumption was measured during 90 h of germination at 25 °C using the Seed Respiration Analyser instrument. The starting metabolism rate (SMR; % O2. h-1) and the time to seeds reaching 50% O2 level (R50; h) were calculated from the oxygen depletion curves. The CF average was 944.19, 601.65, and 566.05 for G, Y and C. The SMR was 0.36; 1.08, and 1.94 %. O2. h-1, and the R50 was 45.90; 25.54 and 19.13 h, respectively for G, Y and C. The germination and viability percentages were 11.1 and 58 (G), 65.4 and 85 (Y), 83.3 and 87% (C). The highest chlorophyll retention, the lowest O2 consumption, and the longest O2 depletion time were observed in G. These results were also in accordance with the decreasing germination and viability percentages in G with respect to Y and C. In conclusion, HDS severely affected chlorophyll degradation, the O2 consumption and, indirectly, the metabolism rates of green soybean seeds. The lowest metabolism rates of these seeds would be associated with a low physiological quality. However, other physiological conditions, such as embryo seed dormancy, could not be rule out and deserve further study.chlorophyll, Glycine Max, green seeds, O2 consumption, seed germination
Biopelícula de Azospirillum argentinense: implicancia de las poliaminasSilvana Díaz HerreraZawoznik, M.S. (1); Benavides M.P. (1); Groppa M.D.(1)(1) Cátedra de Química Biológica Vegetal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113) Buenos Aires, Argentina.Among plant growth-promoting rhizobacteria (PGPR), Azospirillum argentinense Az39 is a reference strain for inoculants in Argentina, and the study of its interaction with plants has raised great interest . Despite its importance and widespread use, studies on the molecular traits involved in plant colonization are lacking. Since biofilm formation is one of the first steps in root colonization and considering that polyamines are involved in numerous physiological processes in both plants and bacteria, we aimed to study polyamine´s role in this process.
Biofilm formation was quantified by crystal violet staining in 96-well plates, where the target microorganism was cultured for 3 days at 30 °C in the presence of three different concentrations of the polyamines putrescine, spermidine, spermine, and cadaverine separately. The effect of the putrescine biosynthesis inhibitors DL-α-difluoromethyl arginine (DFMA) and DL-α-difluoromethyl ornithine (DFMO), and the spermidine and spermine inhibitor cyclohexylamine (CHA), was also studied. All treatments were compared to controls without polyamines or inhibitors.
The addition of the 4 polyamines inhibited biofilm formation in a dose-dependent manner, except for the 0.5 mM Spd concentration. Polyamine biosynthesis inhibitors led to an increased biofilm formation. The results obtained so far allow us to conclude that polyamines are involved in biofilm formation by Azospirillum argentinense Az39.
Azospirillum, biofilm, polyamines
NAC1 directs CEP1-CEP3 peptidase expression and modulates root hair growth in ArabidopsisDiana Rosa Rodríguez GarcíaEliana Marzol, Yossmayer del Carmen Rondón Guerrero, Javier Martínez Pacheco, Victoria Berdion Gabarain, Leonel E. Lopez, Gabriela Díaz Dominguez, José M. EstevezFundación Instituto LeloirPlant genomes encode a unique group of papain-type Cysteine EndoPeptidases (CysEPs) containing a KDEL endoplasmic reticulum (ER) retention signal (KDEL-CysEPs or CEPs). CEPs process the cell-wall scaffolding EXTENSIN proteins (EXTs), which regulate de novo cell wall formation and cell expansion. Since CEPs are able to cleave EXTs and EXT-related proteins, acting as cell wall-weakening agents, they may play a role in cell elongation. Arabidopsis thaliana genome encodes three CEPs (AtCPE1-AtCEP3). Here we report that the three Arabidopsis CEPs, AtCEP1-AtCEP3, are highly expressed in root-hair cell files. Single mutants have no evident root-hair phenotype, but atcep1-3 atcep3-2 and atcep1-3 atcep2-2 double mutants have longer root hairs (RHs) than wild type (Wt) plants, suggesting that expression of AtCEPs in root trichoblasts restrains polar elongation of the RH. We provide evidence that the transcription factor NAC1 activates AtCEPs expression in roots to limit RH length. Chromatin immunoprecipitation indicates that NAC1 binds the promoter of AtCEP1, AtCEP2, and to a lower extent to AtCEP3 and may directly regulate its expression. Indeed, inducible NAC1 overexpression increases AtCEP1 and AtCEP2 transcript levels in roots and leads to reduced RH growth while the loss of function nac1-2 mutation reduces AtCEP1-AtCEP3 gene expression and enhances RH growth. Likewise, expression of a dominant chimeric NAC1-SRDX repressor construct leads to increased RH length. Finally, we show that RH cell walls in the atcep1-1 atcep3-2 double mutant have reduced levels of EXT deposition, suggesting that the defects in RH elongation are linked to alterations in EXT processing and accumulation. Taken together, our results support the involvement of the NAC1-AtCEP regulatory module in controlling RH polar growth through EXT processing and insolubilization at the cell wall.

Participation of tomato ERF30 in plant immunity against Pseudomonas syringae pv. tomato (Pst)Sirvent, EmiliaPombo, Marina A.; Rosli, Hernán G.Instituto de Fisiología Vegetal (INFIVE, CONICET-UNLP)Plants are exposed to a wide variety of pathogens, and to defend themselves they have evolved a two-layered immune system. The first one, called PTI (pattern-triggered immunity), is activated upon the recognition of MAMPs (microbe-associated molecular patterns). Pathogens like Pst can deliver effector proteins into the cytoplasm to promote susceptibility. However, some plants have evolved a second layer of immunity called ETI (effector-triggered immunity) which requires resistance proteins (R) that can recognise these effectors and activate a localized response that culminates in a hypersensitive response (HR). Tomato Rio Grande Pto-R plants detect two Pst effectors (AvrPto and AvrPtoB) with a two-protein complex Pto/Prf.

In this investigation we propose to identify and characterize new transcription factors (TF) implicated in tomato defense against Pst. We previously showed silencing ERF30 using virus induced gene silencing (VIGS) in Nicotiana benthamiana (Nb) lead to a compromised Pto/AvrPto-associated programmed cell death (PCD). In addition silenced Nb 35s::Pto plants challenged with P. s. pv. tabaci carrying AvrPto showed compromised Pto/Prf mediated resistance. We have now measured electrolyte leakage in plants infiltrated with this same strain and observed lower conductivity in ERF30-silencend plats compared to controls.

CRISPR-Cas9 technique was used to develop ERF30 knockout tomato lines. The targeted genomic region of T0 generation was sequenced confirming a homozygous single base deletion in two events and from these plants we generated T1 seeds. Both, T0 and T1, were indistinguishable from wild type plants. PCR reactions amplifying two different regions of the cassette used in CRISPR technique, Cas9 and kanamycin resistance genes, confirmed two plants of each line as transgene free. From these plants we plan to obtain transgene-free homozygous plants in T2 generation to assess the functional status of the defense in the mutant plants.
Plant immunity, transcription factor, molecular biology
Germination proteins of soybean embryonic axesMontechiarini N. (1,3)Yordán E. (1), Perotti V. (2), Collado A. (1), Martínez M. (1), Gosparini C. (1,3)(1) Laboratorio de Fisiología Vegetal. (2) Plataforma AGROBIOTEC-FCA. (3) IICAR–CONICET. Facultad de Ciencias Agrarias. UNR.

Seed germination is completed by the expansion process defining the embryonic axis (Ax) growth before cell division starts. Thus, the cell walls in the elongation zone (EZ) of Ax have to be weakened while the water entries and Ax consequently grow. Expansin proteins primarily promote cell wall remodelling, with the other cell wall proteins secondarily completing the expansion process. This work aimed to identify cell wall remodelling proteins during soybean (Glycine max L. Merr) Ax germination. One hundred soybean Ax, cv. Williams 82, were incubated for 9 h in distilled water at 27 ± 1 ºC. The respective EZ (1 g of tissue) were powdered in liquid N2 and homogenized in 50mM Sodium acetate; 2 mM EDTA; pH 4.5. The wall fragments were collected by centrifugation at 4 ºC and 10000 rpm and extracted in 2 mL 20 mM HEPES; pH 6.8; 1 M sodium chloride; 2 mM EDTA; 3 mM sodium metabisulfite by shacking at 4 ºC for 4 h. Cell wall fragments were removed by centrifugation at 4 ºC and 10000 rpm and the solubilized fraction was precipitated with 0.78 g ammonium sulfate (0.390 g/mL), incubated on ice for 1h and centrifugated at 4 ºC. The precipitate was resuspended in 50 mM sodium acetate. Protein identification was performed by Mass Spectrometry using Uniprot and Phytozome. A total of 2984 unique soybean proteins with, at least, two peptides of high confidence were identified. Thirty-five were cell wall remodelling proteins: 7 Expansins, 2 Xyloglucan endotransglucosylase/hydrolases, 22 Endoglucanases, and 4 Pectinesterases. The classification by gene ontology (AgriGO) showed enrichment in biosynthesis, regulation, response to stimulus, reproduction, developmental, anatomical structure development, catabolism and energy processes. These results evidenced a great cellular activity associated with the expansion process and the early events defining soybean embryonic axes germination.

CRITICAL PERIODS FOR THE EXPRESSION OF VEGETATIVE-REPRODUCTIVE PLASTICITY IN MAIZEFranco EspeletRotili, D. H. (1,2); Maddonni, G. A. (1,2)(1) Facultad de Agronomía, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina. (2) Instituto de Fisiología y Ecología Vinculado a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas (IFEVA-CONICET), Ciudad de Buenos Aires, Argentina.In maize, low plant densities can trigger vegetative and reproductive plasticity mechanisms (i.e., tillering and prolificacy) with positive impacts on grain yield. We evaluated the effect of growth restrictions during the crop cycle to define the critical periods for the expression of plasticity mechanisms. Field studies were carried out in the experimental field of FAUBA during the 2021-2022 and 2022-2023 seasons. Four commercial hybrids with contrasting plasticity mechanisms (phenotypes) were evaluated (T: tillering; P: prolific; PT: prolific+tillering; F: non-tillering non-prolific or flex). Each phenotype was planted at 3 plants per square meter and growth restrictions were imposed with shading during some stages of the crop cycle (S1: V3-V7; S2: V7-V13; S3: V13-R1 and S4: R1-R2), and an unshaded control. In both years, S1 canceled tiller production in all phenotypes except for T in the second year, where tillering was reduced by 40% compared to the control. S2 consistently reduced tiller fertility. Consequently, the number of ears per plant differed among phenotypes (higher in PT due to the contribution of sub-apical and tiller ears) and shading periods. In the controls, the plastic phenotypes showed a higher number of ears and grains per plant than F. In S1 and S2, the number of grains per plant for the prolific phenotypes was higher than for T and F due to shading effects on tiller ears. Kernel weight differed among phenotypes and shading periods, with the highest weights recorded in T under the control, S1 and S2 and the lowest in the prolific phenotypes under S2. When compared with the control, grain yield decreased depending to the shading time and phenotype: S1: -45% and -30% for T and the rest; S2: -40% and -30% for T or PT and the rest; S3: -35% and -55% for P and the rest and S4: -45% for P, -55% for PT or F and -65% for T. In conclusion, there are different critical periods for grain yield depending on the phenotype´s plasticity.vegetative-reproductive plasticity; critical period; grain yield; maize.
Evaluation of chlorophyll "a" fluorescence parameters in tomato (Solanum lycopersicum) under nitrogen and calcium deficiency.LUDI BARZANTE, Luciano (1)FOTI, María Natalia (1) y MICHEL, Analía (1)(1) Facultad de Ciencias Agropecuarias - Universidad Nacional de Entre Ríos, Argentinaver resumen adjunto.photosystem II, leaf position and nutritional stress.
Combinando Biología Sintética y Edición Génica para el desarrollo de una nueva generación de cultivos no-GMO.Emilia BotteroAlessio, A. (1); Vicino, P. (1); Varela, C. (1); Lazzaro, M. (1); Lieber, L. (1)BioHeuris, Rosario, ArgentinaBioHeuris desarrolla cultivos tolerantes a herbicidas con el fin de controlar las malezas y reducir la carga de estos en el medio ambiente. El desarrollo de los productos está basado en la interacción de dos plataformas tecnológicas. La primera, denominada HEURIK™, combina estrategias de evolución dirigida de proteínas y biología sintética, para identificar mutaciones que confieran resistencia a herbicidas en los cultivos. El enfoque de HEURIK™ se basa en el uso de chasis microbianos y herramientas high-throughput que pueden lograr en unas pocas semanas lo que con las técnicas de mutagénesis tradicional requerirían cientos de hectáreas y años de pruebas de campo. 

La segunda plataforma tecnológica, denominada SWAP™, combina protocolos de cultivo in vitro con técnicas de edición génica basadas en CRISPR/Cas para introducir, de una manera precisa, las mutaciones identificadas en HEURIK™, directamente en líneas elite. Es importante mencionar que la visión de la empresa se enfoca en desarrollar tecnologías con tolerancia a principios activos de herbicidas clasificados con bajos valores de Environmental Impact Quotient (EIQ), lo que garantiza un bajo nivel de riesgo para la salud de los productores, consumidores y el ambiente.

Las principales ventajas del uso de estas tecnologías para mejorar cultivos frente a diferentes estreses bióticos y/o abióticos, así como para el control de malezas, incluyen la disminución de los tiempos y costos de desarrollo en comparación con métodos de mutagénesis tradicional. Asimismo, los cambios generados en el genoma con dichas herramientas de edición génica son genéticamente indistinguibles de aquellos producidos por mutagénesis tradicional, por lo que son regulados como no-GMO en la mayoría de los países de América y Asia.   
gene editing, CRISPR/Cas, herbicide, crops
Transcriptomic changes triggered by ferroptosis inhibitors drive heat stress tolerance in Arabidopsis thaliana.Gabriel Alejandro LópezDistéfano, A.; Bauer, M.V.; Pagnussat, G.C.Instituto de Investigaciones BiológicasFerroptosis is an iron-dependent and oxidative type of cell death which occurs in Arabidopsis plants upon heat stress. Treatment with canonical ferroptosis inhibitors CPX (an iron-chelant) and Fer-1 (a lipophilic antioxidant) allows plants to survive lethal temperatures. In this work, we aimed to investigate if treatment with ferroptosis inhibitors triggers a response similar to the one observed in “thermopriming”, a phenomenon in which plants exposed to sub-lethal temperatures are able to tolerate higher temperatures. We constructed RNAseq libraries from plants treated with canonical ferroptosis inhibitors CPX and Fer-1. Notably, these treatments resulted in the upregulation of 64 genes. Among these induced genes, we found the splicing factor SWAP, GATA2 -a transcription factor related to heat stress response- and Arabinogalactan Protein 30 -related to cell wall integrity-. The expression pattern of these genes was studied in the thermopriming process, and we are currently constructing plants carrying CRISPR/dCas9, which will lead to specifically activate these genes in their chromosomal context. This research aims to improve plant resilience to extreme temperatures and enhance agricultural productivity in the present context of climate change.ferroptosis, heat stress, biotic stress
Auxin and coronatine signaling converge in guard cellsRios Camila Alejandra (1)Pieckenstein, F. (2); Gudesblat G.E (1)(1) Instituto de Biociencias, Biotecnología y Biología traslacional, UBA, Argentina. (2) Instituto Tecnológico de Chascomús, CONICET, Argentina.Certain hormones and bacterial compounds are known to inhibit ABA-induced stomatal closure, including auxins and coronatine, a bacterial toxin which is a structural analog of the jasmonate-isoleucine conjugate. Both are known to affect the activity of inward rectifying potassium channels as well as ROS synthesis in guard cells.
In this work we seeked to understand the mechanism through which auxins and coronatine inhibit ABA-induced stomatal closure. Through the analysis of various Arabidopsis mutants affected in the signaling or transport of auxins and coronatine, we found that mutants insensitive to inhibition by coronatine of ABA-induced stomatal closure coi1-16, lecrkVI-2.1, mpk3, mpk6, npr1 and rbohd were also insensitive to the auxin IAA. On the other hand, tir1-1 and aux1 mutants, affected respectively in the perception and transport of auxins, display markedly reduced stomata reopening after three hours of incubation with the coronatine-producing bacterium Pseudomonas syringae pv. tomato DC3000 (which initially induces stomatal closure through PAMPs). In addition, natural variability was found for stomatal sensitivity to both coronatine and auxins. As far as it is known, the perception of both types of compounds occurs independently, so it is complex to explain the simultaneous insensitivity of auxin and coronatine in the aforementioned mutants.
On the other hand, we have found that mutants affected in the silencing mechanism ago4, dcl2/3/4 and rdd also presented stomatal insensitivity to auxins, which may suggest that the regulation of sensitivity to this hormone could be partly mediated by transcriptional mechanisms.
stomata, auxin, coronatine, silencing, PAMPs
Analysis of secondary metabolites and their induction by salinity (NaCl) in hairy roots of Lycium humileMariana Andrea ReginatoTobias Blank1, Virginia Palchetti2, Julia Iparraguirre3, Jutta Papenbrock1, Mariana Reginato31Leibniz Universität Hannover, Germany 2Univerisdad Nacional de Córdoba, Argentina 3Universidad Nacional de Río Cuarto, Argentina.Lycium humile Phil. inhabits extreme saline soils in the Altiplano-Puna region (Central Andes, South America). As one of the most salt-tolerant halophytic Solanaceae, L. humile represents a promising experimental model to study salt tolerance in plants of this family. This species can effectively grow at high NaCl concentrations, at least up to 750 mM NaCl, as well as in the absence of salts in the medium. In this study, stable hairy root (HR) cultures of L. humile were obtained by infection of young seedlings with Rhizobium rhizogenes and the three best growing lines (A, B, and C) were selected and subjected to six different NaCl concentrations. The growth and contents of total phenolics, total flavonoids, and total alkaloids were analyzed. Low salinity (100 mM) significantly decreased the HR growth, in contrast to the response previously observed in the growth of whole plants, which was only affected at concentrations above 750 mM NaCl. This suggests that isolated hairy roots lack certain mechanisms that whole plants have to cope with salt stress. HR line B showed a significant increase in total phenolics and total flavonoids under 190 mM NaCl, compared to both lower NaCl treatments of the same line and 190 mM treatments of the other HR lines. Moreover, HR line B showed a considerable amount of alkaloids without exposure to salinity, comparable to the content found in the roots of greenhouse-grown plants. Further experiments are planned to determine the total alkaloid content in response to salt stress and possibly identify novel interesting plant secondary metabolites.Plant physiology, salt tolerance, secondary metabolites
Role of brassinosteroids in salt tolerance responses of halophytic woody plants: a study on Strombocarpa strombulifera (Lam.) A. Gray plants.Llanes, A (1,2).Gatica M. (2); López E. (2); Masciarelli O. (1); Iparraguirre J. (1,2).(1) Instituto de Investigaciones Agrobiotecnológicas (INIAB-UNRC)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); (2) Universidad Nacional de Río Cuarto (UNRC), Río Cuarto, Argentina.Brassinosteroids (BR) are a type of hormones that regulate growth and stress responses of plants. However, how BR levels modify the salt tolerance resistance of halophytic woody plants requires further investigation. In this study, the role of BR in growth responses of Strombocarpa strombulifera plants under salinity was analyzed. Plants were grown in hydroponic solutions and exposed to NaCl, Na2SO4, or their iso-osmotic mixture at different osmotic potentials (-1.0, -1.9, and -2.6 MPa). To clarify the role of BR and its relation with abscisic acid (ABA), the control (without salt) and salt-treated plants were sprayed with ABA. Different parameters were measured in all plants, including shoot height, root length, root biomass, shoot biomass, transpiration rate, hydric content, and ABA and BR endogenous levels. Root and leaves of salt-treated plants showed a high production of 24-epibrassinolide and castasterone (BR compounds), which increased in the plants sprayed with ABA. Na2SO4-treated plants showed reduced growth, and elevated levels of ABA and BR. In iso-osmotic mixture-treated plants intermediate values were observed in the levels of these phytohormones as compared to NaCl or Na2SO4 treatment. This study indicates that BR would contribute to sodium salts tolerance responses of halophytic woody S. strombulifera plants. These findings contribute to the understanding of how BR biosynthesis regulation is involved in the responses to different sodium salts in soils, which could be used as new tools for forest breeding.abscisic acid, brassinosteroids, halophytic woody plants, sodium salt responses, tolerance.
BdPAP2, a SEPALLATA-Like gene, is involved in regulating flowering time and inflorescence architecture in Brachypodium distachyonGaido, J. (2)Bassi, M. (1), Uberti Manassero, N. (1), Vegetti, A. (2), Dezar, C. (2)(1) Facultad de Ciencias Agrarias, Universidad Nacional del Litoral. (2) ICiAgro, CONICET - UNL.The Pooideae subfamily includes economically important crops like wheat, barley, and oats. In these cereals, precise control of reproductive traits is crucial for optimizing grain yield, and its study has been facilitated by the emergence of Brachypodium distachyon as a model plant. PAP2, a SEPALLATA-Like gene, plays a role in regulating flower development in rice, but its function in Pooideae remains unknown. This study aimed to elucidate the role of the B. distachyon homologue of PAP2, BdPAP2, in the flowering process. For this purpose, two genetically modified lines of the B. distachyon Bd21.3 ecotype were analyzed: BdPAP2-mut, a knock-down mutant in BdPAP2, and BdPAP2-oe, an overexpressing line. Interestingly, BdPAP2-oe plants flowered earlier than the wild-type genotype, while BdPAP2-mut plants showed a delay in spikelet emergence compared to Bd21.3 plants. Furthermore, inflorescences of the BdPAP2-oe plants had fewer spikelets per spike, and the spikelets appeared to be adpressed to the main axis since the pulvinus has not been activated. The inflorescences of the BdPAP2-mut plants, on the other hand, exhibit an architecture similar to those of Bd21.3. Additionally, in the BdPAP2-oe plants, the axillary meristem of the flag leaf node is activated, which results in the production of fertile spikelets. Among the three genotypes examined, BdPAP2-mut displayed the lowest number of spikes per plant and showed some empty glumes, indicating incomplete fruit development in the gynoecium. This is evident from the lower number of grains per spike and the reduced grain weight per plant observed in this genotype compared to the wild-type and BdPAP2-oe genotypes. Finally, in the 10-grain weight determination, no significant differences were observed among the three genotypes. These results suggest that BdPAP2 may play a role not only in the transition from vegetative to reproductive meristem but also in determining inflorescence architecture and yield in B. distachyon.Brachypodium distachyon, flowering, Pooideae
Unravelling the responses of non-model tree species to the environment: the case of Nothofagus pumilio a key species of the subantarctic forestsArana, María VerónicaEstravis-Barcala M (1,§), Cagnacci J (1), Gaischuk S (1), Gonzalez-Polo M (2), M, Martinez-Meier A (1), Moyano T (3), Cavia R (4), Hua W(5), Weigel D (6), Lia V (7), Gutierrez RA (3), Bellora N (8), Arana MV (1)(1) Instituto de Investigaciones Forestales y Agropecuarias Bariloche (INTA EEA Bariloche-CONICET), Bariloche, Rio Negro, Argentina. (2) INIBIOMA, CONICET-Universidad Nacional Comahue, Bariloche, Rio Negro, Argentina. (3) Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile. (4) Instituto de Ecología, Genética y Evolución de Buenos Aires (UBA - CONICET), Buenos Aires, Argentina. (5) College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, China (6) Max Planck Institute for Biology Tübingen, Tübingen, Germany. (7) Instituto de Agrobiotecnología y Biología Molecular (INTA Castelar – CONICET), Buenos Aires, Argentina. (9) Fundación INTECNUS. Comisión Nacional de Energía Atómica, Bariloche, Rio Negro, Argentina. (§) Present address: Umea Plant Science Centre, Umea, Sweden.Forests cover about 41 million km2 of the surface of the planet, and by sequestering large amounts of carbon they comprise a key element in countering the effects of increased CO2 production, such as global climate change. Despite this, predicted changes in climate are expected to have major impacts in trees. Revealing the physiological and molecular bases of their responses to the environment is therefore crucial for the development of conservation strategies and for breeding stress-resistant genotypes. Nothofagus pumilio is one of the tree species with the larger distribution area in Patagonia. This species ranges in elevation from 0 to 2000 meters above sea level in high latitudinal zones (55°S). However, north of 41°S, it occurs only in the sub-alpine zone –the coldest environments-, suggesting that it lacks adaptation to heat. In this talk I will show the way in which we use genomic tools in combination with laboratory and field experiments to explore the molecular bases of abiotic stress response in N. pumilio. We mainly focused on stress by high temperatures given that this factor resulted a major driver of seedling mortality in the forest.  We generated a draft genome that nowadays condenses the analysis of differential expression experiments, genotype-phenotype associations and functional studies. We identified a wide spectrum of heat-responsive transcripts, including 59 transcription factors, alongside spliceosome machinery and hormone pathways. Both in field and laboratory experiments photosynthesis is apparently affected by stress. Preliminary association studies in seedling growing in natural environments identified nucleotide polymorphisms related to the phenotypic variation in photosynthetic traits, with the corresponding genomic regions encompassing genes related to development and stress response. Overall our work provides the first clues in the stress response of N. pumilio, and provides information of potential use in biotechnological programs.Abiotic stress, ecophysiology, genomics, trees, seedling
Plants’ deceiving game to tame bacterial foesCristian H. Dannaseminar talkDepartment of Biology, University of Virginia. Charlottesville, Virginia, USAPlant immunity relies on Pattern Recognition Receptors (PRRs) to perceive Microbe-Associate Molecular Patterns (MAMPs) from invading bacteria to induce defense responses that prevent attempted infections. Since the expression of virulence genes is key for bacterial pathogens to colonize plants, alterations in the expression of virulence, induced by MAMPs perception, are key for the host to remain healthy. The activation of plant immunity with MAMPs prior to the infection suppresses the onset of bacterial virulence by promoting the accumulation of Gln and Ser in the leaf apoplast. This seems paradoxical considering that, among other free amino acids, pathogenic bacteria use Gln and Ser as only sources of carbon and nitrogen to support bacterial growth. Indeed, when colonizing naive (non-immunized) plants, bacterial pathogens suppress plant immunity to prevent the early accumulation of apoplastic amino acids. Later on in the infection, and after suppressing plant immunity, pathogenic bacteria produce and secrete small molecules that impact plant amino acid metabolism and transport. This manipulation of the host physiology leads to the accumulation of apoplastic amino acids, Glu and Asp among other amino acids that support fast bacterial growth and virulence expression. In brief, plants have evolved defense mechanisms to deceive incoming microbes with easy-to-use metabolites (i.e. Gln and Ser) at a time when the priority of the incoming bacterium should be the expression of virulence genes to suppress plant immunity.plant immunity amino acid transport bacterial pathogens
Molecular mechanisms controlling early development in Arabidopsis.Vacs, P. (1)Rasia, R. (1); González Schain, N. (1)(1) Instituto de Biología Molecular y Celular de Rosario, IBR, Argentina.Seedlings germinating under the soil surface have evolved to an exquisite developmental program termed skotomorphogenesis. In darkness, seedlings rapidly elongate the hypocotyl toward the surface in a desperate search of light, while protecting the apical meristem against mechanical damage by forming a hook between the hypocotyl and the two closed cotyledons. A proper skotomorphogenic growth must be achieved until seedlings reach the light to ensure survival as they depend on limited seed reserves.
In our previous work, by studying mutants in the core components of miRNA microprocessor, we uncovered a microprocessor-independent function of HYPONASTIC LEAVES 1 (HYL1) as a repressor of hook development. Our findings have led to hypothesized a possible connection between HYL1 action in skotomorphogenesis and the well-established and crucial function of the phytohormones auxins in hook development. We discovered that HYL1 plays a crucial role in establishing the auxin gradient in apical hooks, however, the precise mechanism responsible for this process remains unknown.
Polar auxin transport (PAT) is essential for generating hormone gradients in different plant tissues and mainly depends on the polarized localization of PIN auxin transporters in the plasma membrane. PAT is regulated by several mechanisms, and flavonoids such as quercetin and kaempferol have been proposed as possible PAT modulators. In this work, we study the localization of auxin transporter PIN3 in hooks of HYL1 mutants and also seek for possible alterations in the flavonoid pathway.
skotomorphogenesis, HYL1, hook development, auxins, flavonoids
Cell architecture during plant growth and developmentNatalia BurachikVacs, P. (2); Santin, F. (1); González-Schain, N. (2); Mazzella, A. (1)(1) Instituto de Investigaciones en Ingeniería y Biología Molecular “Dr. Hector N. Torres” (INGEBI); CONICET. (2) Instituto de Biología Molecular y Celular de Rosario (IBR); CONICET-UNR.The size and shape of plant organs are mainly determined by the timing, the duration and the directionality of cell growth. Each plant cell must integrate endogenous and external signals from neighbouring cells in order to execute coordinated decisions for growth and finally shape cell architecture. We use Arabidopsis´ early development as a model for studying signal coordination for differential cell growth, from seeds germinating and developing in darkness (skotomorphogenesis) until they reach the light and change to an autotrophic lifestyle (photomorphogenesis). Photoreceptors, different factors acting as master regulators and many phytohormones like auxins or ethylene, among others, have a great impact on early development and growth´s decisions. Cortical microtubules (cMTs), as an integral component of cytoskeleton, also play key roles in determining growth directionality, and their intrinsic dynamics nature needs synchronization with the external and internal signals. Despite its importance, the precise coordination of these signals for cell growth in early development remains poorly understood. In this work we analyse the physiology and cMTs dynamics of the marker line GFP-MAP4 in different photo and skotomorphogenic mutant backgrounds. We evaluate microtubule array patterns in hypocotyl and apical hook cells during skotomorphogenic growth in photomorphogenic mutants in the dark, such as cop1, pif1pif3pif4pif5, and hyl1, and in a skotomorphogenic mutant in light (hy5). By examining these results and considering the dependency of cMTs dynamics on light/dark signalling regulators, we aim to get insights into the coordination of cell growth in early development.microtubules, cellular growth, cell biology, skotomorphogenesis
ZmS5H: A MULTI-FUNCTIONAL ENZYME REGULATING PLANT DEVELOPMENT AND SENESCENCE IN MAIZESerra, PalomaPetrich, J., Righini Aramburu, S., Falcone Ferreyra, M.L., Casati, P.Centro de Estudios Fotosintéticos y Bioquímicos - CEFOBI (CONICET-UNR)Salicylic acid (SA) is a phytohormone that plays a crucial role regulating various aspects of plant life, including disease resistance, leaf senescence, flowering time, and thermogenesis. SA undergoes chemical modifications such as methylation, hydroxylation, or conjugation with sugars or amino acids. SA hydroxylation is catalyzed by enzymes known as SALICYLIC ACID HYDROXYLASES (SHs) and plays an essential role in plant development and response to pathogens. In our lab, we successfully identified the first SA hydroxylase in maize plants, known as salicylic acid 5-hydroxylase (ZmS5H), a 2-oxoglutarate dependent dioxygenase (2-ODD) that catalyzes the conversion of SA into 2,5-dihydroxybenzoic acid (2,5-DHBA) by hydroxylating the C5 position of its phenyl ring. Since some 2-ODD enzymes involved in plant phenolic metabolism can accept various phenolic compounds as substrates, we tested two flavanones (naringenin and eriodictyol) and one dihydroflavonol (dihydroquercetin, DHQ) as putative substrates of ZmS5H. We observed that ZmS5H also exhibits flavonol synthase activity, as it can convert dihydroquercetin (DHQ) into the flavonol quercetin (QUE). To validate the dual functionality of ZmS5H, we quantified SA, 2,5-DHBA, and QUE levels by LC-MS in young maize leaves of wild type (W22) and mutant s5h plants, quantifying reduced levels of both 2,5-DHBA and QUE in the absence of S5H. However, in adult maize leaves, the s5h mutant lines showed an accumulation of QUE. Furthermore, a phenotypic characterization of maize plants indicated that s5h mutant lines exhibited increased senescence and affected plant growth. These findings strongly suggest that ZmS5H adapts its functionality based on the specific needs of each stage of plant development, playing a pivotal role in both plant growth and senescence.maize, flavonoids, salicylic acid, 2-ODDs, growth, senescence, plant physiology
Impact of heat waves during the spring on the ecophysiology of young olive trees (Olea europaea L.)Argañaraz, R.A. (1)Miserere, A. (2); Agüero Alcaras, L.M. (3); Rojas Barrionuevo, F.G. (4); Castro, D.N. (1); Herrera, C.J. (1); Cortes Molina, M.V. (1); Rousseaux, M.C. (1); Searles, P.S. (1)(1) Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-Provincia de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET), Entre Ríos y Mendoza s/n, Anillaco 5301, La Rioja, Argentina (2) Centro de Investigación e Innovación Tecnológica (CENIIT), CONICET, Universidad Nacional de la Rioja (UNLaR); Gdor. Luis Vernet y Apostol Felipe (5300), La Rioja, Argentina (3) Agencia de Extension Rural Aimogasta, Instituto Nacional de Tecnología Agropecuaria (INTA), Ruta Nacional 60, Aimogasta (5310), La Rioja, Argentina (4) Departamento Académico de Ciencias y Tecnologías Aplicadas a la Producción, al Ambiente y al Urbanismo (DACyTAPAU), Universidad Nacional de La Rioja, Av. Luis M. De la Fuente s/n, Ciudad Universitaria de la Ciencia y de la Técnica, La Rioja 5300, La Rioja, Argentina.The frequency and intensity of heat waves have increased in recent years with climate change.  Understanding olive tree responses to these events in Northwest Argentina, where very warm air masses are common during the spring, may play a crucial role in planning production strategies. Thus, the objective of this study was to evaluate the ecophysiological responses of young olive trees to experimentally imposed heat waves during the spring in La Rioja, Argentina.  One-year-old cv Coratina plants were placed in either near-ambient control (C) or heated (T+) open top chambers (OTCs) for periods of seven days. The air temperature was near-ambient in the control OTCs and increased by around 8°C during the day and 5°C at night in the T+ OTCs. Photosynthetic gas exchange and vegetative growth variables were measured for three individual heat waves conducted in September, October, and November. Measurements were carried out prior to each heat wave (-2 days), during the heat wave (days 3 and 6), and after each heat wave (+2 days).  And, different plants were used in each heat wave.  Net photosynthesis was similar between the C and T+ plants during all three heat waves, but foliar transpiration was greater on day 6 of the September and October heat waves. No differences were apparent during the third heat wave when air temperatures were very high in both C and T+ OTCs (>35 °C). Stem elongation was significantly greater in T+ than in C during the first wave when air temperatures were mild, but no differences occurred in the second and third waves.  Overall, the results suggest that heat waves will not adversely affect net photosynthesis during the spring unless very high temperatures are reached, but leaf transpiration will likely be increased.  Further studies will assess whether the thermal tolerance to extreme temperatures changes after exposure to heat waves.Coratina, Photosynthesis, Stem growth, Transpiration, Temperature
Deciphering HLR1 function in photoprotectionManuel BalpardaJonas Matteo Böhm, Yaroslav Zaplatnikov, Veronica G. MaurinoMolekulare Pflanzenphysiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Kirschallee 1, 53115 BonnDuring cellular activity, spontaneous reactions, as well as side reactions of promiscuous enzymes, can produce highly reactive biological compounds like Reactive Carbonyl Species (RCS) that can be toxic to the cell. The main pathway for RCS scavenging is the glyoxalase (GLX) system, which consists of the enzymes glyoxalase I (GLXI) and glyoxalase II (GLXII). Apart from these proteins, seven gene loci in Arabidopsis encode HLR-like proteins. HLR proteins share only 17-25% identity with the GLXI proteins, indicating an evolutionarily and functionally distant relationship with active GLXI.
Optimization of NAD-ME for C4 physiology in eudicots: A three-way dance storyVeronica Maurino1Hüdig, M. (1); Tronconi M.A. (2)(1) Department of Molecular Plant Physiology, Institute of Cellular and Molecular Botany, University of Bonn, Germany. (2) Centro de Estudios Fotosintéticos y Bioquímicos, Universidad Nacional de Rosario, Argentina.In plant mitochondria, NAD-malic enzyme (NAD-ME) has a housekeeping function in mitochondrial malate metabolism. In different plant lineages, NAD-ME was independently co-opted in C4 photosynthesis. In the C4 Cleome species, Gynandropsis gynandra and Cleome angustifolia, all NAD-ME genes (NAD-MEα, NAD-MEβ1, and NAD-MEβ2) were affected by C4 evolution and are expressed at higher levels than their orthologs in the C3 sister species Tarenaya hassleriana. In T. hassleriana, the NAD-ME housekeeping function is performed by two heteromers, NAD-MEα/β1 and NAD-MEα/β2, with similar biochemical properties. In both C4 species, this role is restricted to NAD-MEα/β2. In the C4 species, NAD-MEα/β1 is exclusively present in the leaves, where it accounts for most of the enzymatic activity. G. gynandra NAD-MEα/β1 exhibits high catalytic efficiency and is differentially activated by the C4 intermediate aspartate, confirming its role as the C4-decarboxylase. We show that during evolution, NAD-MEβ1 repeatedly lost its catalytic activity; its contribution to the enzymatic activity of the heteromer results from a stabilizing effect on the associated α-subunit and the acquisition of regulatory properties. We conclude that in mitochondria of C4 species, the functions of NAD-ME as C4 photosynthetic decarboxylase and as a housekeeping enzyme coexist and are performed by isoforms that combine the same α-subunit with differentially adapted β-subunits.C4 photosynthesis, mitochondrial malate metabolism, C4 evolution
THE DIVERSE IRON DISTRIBUTION IN SEEDSHannetz RoschzttardtzVidal Elgueta, A. (1)(1) Pontificia Universidad Católica de ChileMost of our knowledge on seed iron accumulation is mainly based on studies performed in the model plant Arabidopsis thaliana for which it has been described that iron accumulates in the vacuoles of the endodermis cell layer during seed maturation. However, little is known about iron allocation and distribution in seeds of other plants. Interestingly, we have found that different strategies exist in other plant species. Our results indicate that dicot seed embryos have a different iron distribution pattern compared to Arabidopsis. Using mutants and transgenic plants approaches we modified iron distribution in Arabidopsis embryos, however, these changes had not impact in the total iron content in seeds, suggesting that embryonic iron distribution do not control total seed iron content.

In order to study the effect of agriculture in monocot seeds, we performed a histological and quantitative study of iron in archaeological maize seeds from prehispanic times recovered from Tarapacá, Atacama Desert. Our findings revealed changes in iron distribution at the sub-cellular level in embryos from ancient versus new varieties of maize, and a progressive decrease in iron content from the oldest maize to modern specimens was observed. We interpret the results as an effect of prehispanic agriculture over the micronutrient composition of maize.
seed, iron, histology
Sunburn effect on cell wall of pear skin during post-harvest ripening.Spera, Nazarena (1,2)Vita, L.I.(2,3); Civello, P.M.(4,5); Colavita, G.M. (2,3)(1) Universidad Nacional de Río Negro, Sede Andina, Argentina. (2) Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue, subsede IBAC (CONICET-UNCo), Argentina. (3) Facultad de Ciencias Agrarias (UNCo), Argentina. (4) Instituto de Fisiología Vegetal (CONICET-UNLP), Argentina. (5) Facultad de Ciencias Exactas, (UNLP), Argentina.Sunburn is a widely studied symptom that mainly affects the skin, impacting fruit quality. However, there is limited information about the effect of sunburn on the composition of the cell wall and its dynamics in fruit storage and ripening. D'Anjou pear fruits with no sunburn (S0) and mild sunburn (S1) were harvested and stored under conventional cold storage for 5 months. Determinations were made at harvest and at different ripening stages defined by ethylene emission. On the skin was evaluated: lipid peroxidation (TBAs), antioxidant capacity (DPPH), cell wall content (CWC) and its components, such as pectins (P), hemicelluloses (H), lignin (L), and cellulose (C). The pattern of ethylene curves during the ripening of S0 and S1 showed no differences. At harvest, TBAs and DPPH were higher in S1 compared to S0, and these differences persisted during ripening. After storage, DPPH decreased in S0, with a TBAs increase, while S1 showed no changes. The CWC was lower in S1 than in S0 at all evaluated stages, with a marked reduction during storage. At harvest, S1 showed a higher content of branched domains of P, H, and L compared to S0. After storage and during ripening, the content of P in the tissues decreased significantly. In the linear domains of P, this process was slower in S1, and the values were significantly higher compared to S0. In the branched domains, the changes pattern in both tissues was similar, with a significant decrease in the content of P after storage. The differences in L and H at harvest were reduced during ripening, reaching similar final values for S0 and S1. The C content showed no differences due to sunburn. Mild sunburn tissues presented higher oxidative damage along with an increase antioxidant capacity at harvest, which could have a positive effect on the reduction of oxidative damage caused by ripening. Excessive sun exposure promoted lignin accumulation and delayed cell wall disassembly during ripening, mainly at the pectin level.Pyrus communis; sun damage; peel; pectin; lignin; oxidative metabolism.
A coffee hope tale: Coffea arabica Castillo and Caturra varieties could survive in a dryer world with reliable physiological strategies.HERNANDEZ, S. (1)RADA, F. (1); LASSO, E. (1,2)1Department of Biological Sciences, University of the Andes, Bogotá, Colombia, 2 Smithsonian Tropical Research Institute, Panama, Panama.Coffee (Coffea sp.) is one of the most traded products worldwide, and one of the largest producers is Colombia, where coffee generates 2 million jobs approximately. Under climate change scenarios, some coffee cultivation areas in Colombia will decrease by 2050 as rainfall will decline by 10% to 40% in the northern regions that produce some specialty coffees. Nonetheless, since some coffee varieties might respond differently to drought, we need to understand how varieties cultivated in the region would respond to water scarcity to enhance the resilience of Colombian coffee crops. In our study, we investigated the physiological responses to water deficit of Castillo and Caturra varieties of Coffea arabica. We had 18 plants of each variety in a growth chamber at 23oC and suspended irrigation for 27 days (drought treatment) to half of the plants while the other half were continuously watered (control treatment). Afterward, drought treatment plants were re-irrigated for ten days to record their recovery. We measured water relations: leaf water potential (YL), osmotic potential at turgor loss (Yptlp) and modulus of elasticity (e); gas exchange: stomatal conductance (Gs), transpiration (E) and photosynthetic (A) rates, and plant height. During the non-irrigation period, usually Castillo had higher YL, E and A rates than Caturra. However, Caturra showed a lower Yptlp under drought compared to the control group, suggesting an active osmotic adjustment. Drought treatment plants were smaller than control plants, but this was not significant between the varieties under drought conditions. After rewatering, both varieties recovered to nearly physiological values as the control plants. Our data indicate that both varieties may respond similarly to drought and can recover from drought events of up to 27 days. Future research should evaluate adult plants and the effect of drought on fruit production to decide which variety will be best to grow in northern Colombia regions.Coffea arabica Castillo variety, Coffea arabica Caturra variety, drought, plant physiology.
Problems caused by excessive or insufficient seed dormancy in crops. Search for solutions in sunflower and grain sorghum.Rodríguez, M.V. (1,2)Batlla, D. (1,3); Benech-Arnold, R.L. (1,3)(1) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), CONICET/FAUBA. (2) Cátedra de Fisiología Vegetal, FAUBA. (3) Cátedra de Cultivos Industriales, FAUBA.Seed dormancy allows adjusting germination to those environments that maximize the chances of survival of species in the wild. However, in crops, the beginning of the cycle is defined by the sowing date, and the presence of dormancy threatens crop emergence and yield achievement. Domestication and genetic improvement selected against this trait and reduced dormancy levels in many crops, bringing another problem associated with early loss of dormancy: pre-harvest sprouting, frequent in cereals. On the other hand, cultivated sunflowers still maintain high levels of dormancy, causing problems during the production of commercial hybrid seed. In this symposium, different approaches and advances in the study of dormancy in grain sorghum and sunflower are presented, with the combined purpose of understanding the underlying mechanisms and proposing agronomic solutions.Seed dormancy; germination quality; dry afterripening; pre-harvest sprouting; QTL mapping; post-harvest storage; grain sorghum; sunflower
Optimization of the TRAP technique in common bean to study translational dynamics during nitrogen-fixing symbiosis.Andrés Enrique EylensteinReynoso, M.A. (1); Zanetti, M.E. (1); Blanco, F.A. (1)(1) Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT-La Plata, CONICET, La Plata, Argentina.Throughout their evolution, legume plants have maintained the ability to engage in a mutualistic interaction with soil bacteria known as rhizobia, leading to the development of nitrogen-fixing nodules in plant roots. The establishment of this symbiosis is regulated at different levels of gene expression. To gain insight into the translational regulation of mRNAs at early stages of nitrogen-fixing symbiosis in common bean (Phaseolus vulgaris), we adapted the TRAP technique (Translating Ribosome Affinity Purification) to this legume. TRAP allows the isolation of RNAs associated to the translational machinery, referred to as the translatome, by immunoprecipitation using an epitope-tagged version of the RPL18 ribosomal subunit. The isolated RNAs can be sequenced to assess translational changes at a genome-wide scale. Furthermore, we aim to characterize the population of RNAs in active translation from the two main root tissues involved in nodulation by expressing the RPL18 fused to the FLAG epitope under the control of the Expansin7 or the Scarecrow promoter for purification of the epidermal or cortical translatomes, respectively. Based on the expression pattern, we selected the Phvul.007G197900 gene encoding the P. vulgaris RPL18 subunit and expressed it fused to a His-FLAG tag (HF-PvRPL18) in composite plants using the Agrobacterium rhizogenes transformation method. The expression of the HF-PvRPL18 transcript was confirmed by reverse transcription followed by PCR. Ribosomal RNA and mRNAs were detected in TRAP samples from plants expressing the HF-PvRPL18 protein, but not in samples from plants transformed with the empty vector. Based on these results, we concluded that the expression of HF-PvRPL18 in P. vulgaris allows us to affinity purify ribosome-RNA complexes, providing a useful tool to study translational dynamics during root nodule symbiosis in this legume.legume, nitrogen-fixation, ribosome immunopurification, common bean
Effect of legume/cereal intercropping on the inhibition of N2 fixation caused by exogenous N supply in faba beans and peasSebastian Salinas Roco (1)Morales-González, A. (1); Carrasco, B. (2); Del Pozo, A. (1) y Cabeza, R. A. (1)(1) Plant Nutrition Laboratory, Department of Crop Sciencies, Faculty of Agricultural Sciences, Universidad de Talca, Talca, Chile. (2) Centro de Estudios en Alimentos Procesados (CEAP), Talca, Chile.Legumes and cereal intercrop systems increase the use efficiency of soil resources and yields, especially of the cereal, thus is because legumes can fix nitrogen (N2) from air and transfer it to the accompanying crop. On the other side, cereals have longer root system that legumes, thus they can explore more soil volume and absorb more N. Consequently, the exhaustion of soil N reduces the negative effect of inorganic N on the N2 fixation process of legumes. Thus, the goal of this work was to assess the effect of intercrop density on the N2 fixation capacity of two legumes grown at three N levels. To achieve this goal, a pot experiment grown under greenhouse conditions was carried out using two legume species: faba bean (Vicia faba L.) and pea (Pisum sativum L.), grown in monocrop and intercropped with wheat (Triticum aestivum L.) at two plant densities and three N levels. We measured the biomass produced, the proportion of N derived from air (%Ndfa) present in legumes and the cereal, and the land equivalent ratio (LER). The results showed that legumes under the different treatments did not increase the yield. On contrary, wheat increased the biomass as the N level increased. Soil N negatively affected %Ndfa of both legume species, especially when legume grown as sole crop, being peas more sensitive than broad beans. On the other side, the higher the density of wheat plants intercropped with legumes, the lower the inhibition of N2 fixation in the companion legume. Consequently, the lower the N level, the greater the transfer of N from the legume to the wheat. Furthermore, the N transferred to the wheat was higher when this was intercropped with peas than with broad beans. Finally, the LER was higher in intercrop treatments, especially in the absence of N. In conclusion, the intercrop of legumes with wheat helps to circumvent the inhibition of N2 fixation caused by soil N, legumes can transfer up to 30% of the N fixed to the cereal and increase the LER.plant nutrition, intercropping legume/cereal, nitrogen fixation, nitrogen transfer, LER
Effects of phosphorus (P) deficiency on growth and N2 fixation in legumesAmanda Belén Morales González (1)Salinas-Roco, S. (1); Pera, J. (1); Carrasco, B. (2); Del Pozo, A. (1) y Cabeza, R. A. (1)(1) Plant Nutrition Laboratory, Department of Crop Sciences, Faculty of Agricultural Sciences, University of Talca, Talca, Chile. (2) Centro de estudios en Alimentos Procesados (CEAP), Talca, Chile.Phosphorus (P) is pivotal for plant growth and its deficiency results in a decreased biomass production and nitrogen (N) demand, consequently affecting the N2 fixation capacity of legumes. To maintain an optimal P concentration in the nodules, legumes translocate P from leaves to produce energy as ATP and maintain the efficiency of the N2 fixation process. The goal of this work was to evaluate the effects of P deficiency on i) biomass production, ii) N2 fixation (N derived from air, 15N), and iii) the energy status of nodules of three legume species (Phaseolus vulgaris, Vicia faba and Pisum sativum) grown at two P levels. To achieve the goals, pots experiments were carried out under greenhouse and growth chamber conditions. We measured the dry matter yield, the nodule number and weight, the proportion of nitrogen derived from air (%Ndfa), the number of bacteroids inside the nodule, the oxygen saturation (O2) inside the nodule, and the ADP/ATP ratio. Optimal P supply increased shoot and nodule dry matter as well as the amount of nodules in P. vulgaris and P. sativum. Moreover, under P sufficiency the number of bacteroids inside the nodules of V. faba and P. sativum increased. Indeed, the %Ndfa in shoots and roots of Phaseolus vulgaris and Pisum sativum increased at high P level, while for V. faba decreased. On the other hand, O2 saturation in nodules of plants grown under P deficiency occurred earlier than in plants grown under P sufficient conditions. Consequently, O2 concentration was high inside the nodules under P deficiency, suggesting a low amount of leghemoglobin. Finally, the ADP/ATP ratio decreased under sufficient P level for P. vulgaris and P. sativum while it increased for V. faba. We conclude that P allows to maintain more bacteroids inside the nodules and increases the energy status by producing more ATP and demanding more O2 and, consequently fixing more N2.Plant nutrition, phosphorus, N2 fixation, legumes
Nodule Number Control 1, a member of the AP2 family, functions as a negative regulator of bacterial infection and nodule organogenesisMilagros YaculloSoledad Traubenik (1), Mauricio Reynoso (1), Maureen Hummel (2), Julia Bailey-Serres (2), Flavio Blanco (1), María Eugenia Zanetti (1)(1) Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata- CCT La Plata CONICET. (2) Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, CA 92521-0124, USA.Legumes and rhizobia establish a nitrogen-fixing symbiosis results in the formation of a postembryonic lateral root organ, the nodule and requires the suppression of the plant immune response to allow intracellular bacterial infection. Nodule formation and bacterial infection are timely and spatially coordinated through the reprogramming of gene expression which occurs at both transcriptional and post-transcriptional levels. A previous study identified. A transcript encoding the Subunit 3 of the Superkiller Complex (SKI), designated as MtSKI3, as differentially up regulated at the translational level at early stages of the nitrogen foxing symbiosis between Medicago truncatula and Sinorhizobium meliloti. The SKI complex acts along with the exosome in the 3´-5´ degradation of mRNAs. We have found that MtSKI3 is required for nodule formation, bacterial survival, and induction of early nodulation genes such as ENOD40. A recent degradome analysis showed that MtSKI3 affected the miR172-directed endonucleolytic cleavage of the mRNA encoding the APETALA 2 member of transcription factors Nodule Number Control 1 (referred to as MtNNC1). Expression analysis revealed that MtNNC1 is expressed at high levels in roots as compared with aerial tissues, but repressed during nodulation, along with genes involved in defense mechanisms against pathogens. Post-transcriptional silencing of MtNNC1 produced a significant increase in the density of infection events and the number of nodules. These data suggest that MtNNC1 would function as a negative modulator of the formation of nitrogen-fixing nodules. As an alternative approach to elucidate the biological function of MtNNC1, we are currently overexpressing MtNNC1 in M. truncatula transgenic roots. The results will allow a better understanding of the mechanisms by which MtNNC1 exerts its activity during an agronomically relevant biotic interaction such as the nitrogen-fixing symbiosis.molecular biology, transcription factors, nodulation, legumes, nitrogen-fixing symbiosis, biotic interaction
Micro RNA biogenesis and movement in plant defense pimingCambiagno, Damian AlejandroQuevedo, L.; Alanie, N.; Lascano, H.R.Grupo de Biologia del Estrés, Unidad de Estudios Agropecuarios, INTA-CONICETVer resumen adjunto, principalmente para tener en cuenta EL ORDEN DE LOS AUTORESMicro RNAs, plant defenses, priming
Histone modifying enzymes alter rhizobia infection and bacterial survival in the root nodule symbiosisMilagros FerrariTraubenik S., Banini M., Blanco F., Reynoso M. y Zanetti M.E.Instituto de biotecnologìa biologìa molecular, IBBM,La Plata, ArgentinaLegume plants associate with soil bacteria of the genus Rhizobium under conditions of low nitrogen availability in the soil. Rhizobia converts atmospheric nitrogen into reduced forms assimilable by plants in a process known as biological nitrogen-fixation (BNF). In this process the plant forms a new organ, the nodule, where bacteria reside and BNF takes place. Nodule formation is accompanied by dramatic changes in gene expression in the root cells engaged in symbiosis. We have previously shown that translational changes of pre-existing mRNAs contribute to this reprogramming of gene expression in the Medicago truncatula-Sinorhizobium meliloti root nodule symbiosis. Translationally regulated mRNAs included those encoding a histone lysine demethylase (MtPKDM9B) and a histone acetyltransferase (HAT). Both proteins have been involved in chromatin modifications, suggesting that epigenetic might affect the transcription of specific loci during symbiosis. MtPKDM9B is subjected to alternative splicing generating two transcript isoforms, a long isoform that encodes the functional protein and increases its association with the translational machinery in the presence of rhizobia, and a shorter one that encodes a truncated protein. Silencing of both MtPKDM9B isoforms by RNA interference (RNAi) decreases the density of rhizobia infection events and produces smaller nodules with dead bacteria inside. Immunoblot using anti-H3K27me3 antibodies revealed that silencing of MtPKDM9B diminished levels of H3K27me3 in M. truncatula roots, indicating that this histone lysine demethylase plays a role in balancing histone methylation levels. Currently, we are characterizing the function of the long isoform using an artificial microRNA strategy to specifically reduce the levels of this isoform. These results would provide a better understanding of how changes in epigenetic marks affect the reprogramming of gene expression during the BNF
Role of hydrogen sulfide (H2S) and participation of calcium (Ca2+) in stomatal immunity of Arabidopsis thaliana.Schiel PaulaPantaleno, R.; Scuffi, D.; García Mata C.; Laxalt, A.Instituto de Investigaciones Biológicas (IIB) UNMDP - CONICET. ArgentinaStomata are pores in the epidermis of most land plants surrounded by pairs of specialized cells called guard cells (GCs). Changes in GCs turgor pressure modulate the stomatal aperture, which controls gas exchange with the environment. Some pathogens can enter through the stomatal pores to infect the plants, so the induction of stomatal closure implies a first barrier of plant defense, mechanism known as stomatal immunity.

The recognition of Pathogen Associated Molecular Patterns, as the bacterial elicitor flg22, triggers a signaling cascade that involves an increase of cytosolic calcium (Ca2+cyt ) and reactive oxygen species (ROS), leading to stomatal closure.

Hydrogen sulfide (H2S) is a gasotransmitter that has been described to induce stomatal closure. Its main mechanism of action is persulfidation of proteins, a posttranslational modification (PTM) in cysteine residues that regulates the activity or localization of the target protein. Preliminary results obtained in our lab show several persulfidation targets associated with the immune response, specifically in GCs. Among them, PHOSPHOLIPASE C2 (PLC2), which is involved in stomatal closure induced by flg22 and H2S; and some Ca2+ -dependent protein kinases.

In our lab, we demonstrated that the main H2S cytosolic source L-CYSTEINE DESULFHYDRASE 1 (DES1), participates in flg22-induced stomatal closure, but there is no information on the interaction with signaling components of this response. The aim of this study is to investigate the role of H2S/DES1 in stomatal immunity.

In the present work we show that stomatal closure induced by Ca2+ is impaired in des1 mutant plants. However, Ca2+cyt increase in GCs treated with flg22 shows the same dynamic as wild type plants. Moreover, PLC2-silenced plants present reduced production of cytosolic ROS in GCs in response to H2S.
Hydrogen sulfide, stomatal immunity, persulfidation, second messengers.
Biphasic pattern of MsSnRK1-sucrose at early and late stages in salt stress.Barbieri, G. (1)Parola, R. (1,2); Rodriguez, M.S. (1,2)(1) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Unidad de Estudios Agropecuarios (UDEA), Córdoba, Argentina. (2) Instituto Nacional de Tecnología Agropecuaria (INTA), Centro de Investigaciones Agropecuarias (CIAP), Instituto de Fisiología y Recursos Genéticos (IFRGV), Córdoba, Argentina.The rapid changes in land use are leading to new scenarios in alfalfa production. Salinization, a well-known environmental issue worldwide, directly impacts both the crop's yield and the overall productivity of the livestock system. Our previous research showed that salt stress damages the photosynthetic system in leaves which affects carbon content. In this context, low-energy signals induce SnRK1 (Sucrose non-fermenting-related protein kinase), a key regulator in metabolic homeostasis, which was studied in salt-tolerant alfalfa cultivar (Kumen, K) leaves to understand its dynamic responses to salt stress. Plants were maintained under a control-environment chamber in hydroponic conditions, after 20 days (3 true leaves), they were subjected to 200mM NaCl. After treatment, two growth stages of the third leaf were analyzed: an early stage (ES, 3h-1d, expanding leaf) and a late stage (LS, 3d-7d, fully expanded leaf), therefore, facilitating the analyses of both early and late responses. Biphasic patterns were observed at different shifted times, both in the activity of MsSnKR1 and sucrose content. Leaves accumulated a substantial amount of sucrose during the ES of salt stress. During the LS, a peak in sucrose and a significant decrease in starch content at 7 d was observed. Similarly, to sucrose behavior, the activity of MsSnRK1 in the leaves showed a two-phase pattern over time, however, the peaks were observed at 3 h and 3 d compared to the control. Remarkably the readout of marker genes for MsSnRK1 activity (SEN5, ASN1) exhibited a different behavior related to the stage-dependent activity of leaf expansion. These results suggest that the activity-responsive genes would be specific to expanding tissue, while SnRK1 and sucrose work together in a coordinated and biphasic manner to provide responses for salt tolerance in alfalfa.

Supported by CONICET, INTA, INTA-I084; INTA- I100; PICT2021-00229, PUE-UDEA-2018
alfalfa; Medicago Sativa; Salt stress; sugar signaling; SnRK1, tolerance response
Canonical transcriptional gene silencing may contribute to long-term heat response and recoverySanchez, Diego H.Torres, José R.; Botto, Javier F.IFEVA (CONICET-UBA). Facultad de Agronomía, Universidad de Buenos AiresPlant canonical transcriptional gene silencing is involved in epigenetic mechanisms that mediate genomic imprinting and the suppression of transposable elements (TEs). It has been recognized that long-term heat disrupts epigenetic silencing, with the ensuing activation of TEs. However, the physiological involvement of the TGS machinery under prolonged high temperatures has not yet been established. Here, we performed non-lethal extended periodic heat stress and recovery treatments on Arabidopsis thaliana lines mutated on key transcriptional gene silencing factors, analysing transcriptomic changes of coding-protein genes and TEs. Plants bearing MET1, DRM2 and CMT3, and MOM1 mutated alleles showed novel transcriptional properties compatible with functionalities concerning the induction/repression of partially shared or private heat-triggered transcriptome networks. Certain observations supported the idea that some responses are based on thermal de-silencing. TEs transcriptional activation uncovered the interaction with specific epigenetic layers, which may play dedicated suppressing roles under determinate physiological conditions such as heat. Furthermore, physiological experimentation suggested that MOM1 is required to resume growth after stress. Our data thus provide initial evidence that at least one canonical transcriptional gene silencing players may contribute to plant acclimation and recovery from non-lethal long-term heat despite the stress-induced epigenetic disturbance.
Involvement of abscisic acid in modulating ascorbic acid synthesis and accumulation: responses under basal and high incident irradiance conditions.Senn, M. E. (1)Mazorra Morales, L. M. (2), Gergoff Grozeff, G. E. (1); Galatro, A. (1); Da Cruz Saraiva, K. D. (3); Pereira dos Santos, C. (3); Costa, J. H. (3); Gonçalves de Oliveira, J. (2); Bartoli, C. G. (1)(1) Instituto de Fisiología Vegetal (INFIVE), Facultad de Ciencias Agrarias y Forestales y Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata – CCT-CONICET, La Plata, cc 327 (1900), La Plata, Argentina. (2) Setor de Fisiologia Vegetal, Lab. Melhoramento Genético Vegetal (CCTA), Universidade Estadual do Norte Fluminense, 28013-602, Campos dos Goytacazes, Rio de Janeiro, Brazil. (3) Functional Genomics and Bioinformatics, Department of Biochemistry and Molecular Biology, Federal University of Ceará, 60451-970, Fortaleza, Ceará, Brazil.Ver resumen adjunto.ascorbic acid, abscisic acid, ROS-processing metabolism, irradiance.
FIRST CHARACTERIZATION OF TORRONTÉS RIOJANO IN LA RIOJA, ARGENTINA: IMPACT OF PRUNING INTENSITY ON VINE VIGOR AND GRAPE PRODUCTIONRocío MIRANDA (1)Sonia SILVENTE (1), Mariela ASSOF (2), Inés HUGALDE (2)(1)1UNIVERSIDAD NACIONAL DE CHILECITO (UNdeC) Chilecito, La Rioja, Argentina (2) INTA Luján de Cuyo, Mendoza, ArgentinaPruning, an essential vineyard management activity, regulates plant growth and vigor, modulating berry size, and consequently, wine quality. In Chilecito (Antinaco – Los Colorados Valley, La Rioja), Nonogasta and Colonias de Malligasta are two Torrontés riojano (TR) growing sites with long productive traditions and contrasting edaphoclimatic conditions. TR is the only national autochthonous variety (result of the natural cross between Moscatel de Alejandría x Criolla Chica); its perfumed and golden berries produce wine with a marked muscatel character. In this context, three pruning intensities were tested in two vineyards per site, i.e. two properties in Nonogasta and two properties in Colonias de Malligasta. Treatments were control (regular pruning), short (leaving 60% of buds with respect to control), and long (leaving 80% of buds with respect to control). Number of bunches, bunch weight, berry size, pruning weight and yield were assessed in the 2021 and 2022 seasons.

Preliminary results obtained from 2021 season showed significant interactions for yield and pruning weight considering pruning treatments and sites. For number of bunches, significant differences were observed among long vs. short and long vs. control in one vineyard from Nonogasta. Average bunch weight showed no significant interactions among pruning treatments. However, significant differences in yield were observed between sites. A second growing season and further analyses should confirm our results. Planned berry and wine analyses may provide insight into metabolic, aromatic and oenological traits determining possible pruning and site effects on TR. It might be possible that for horizontally trained TR (“parral”), contrasting sites result in stronger effects than the tested pruning intensities. To our best knowledge, this is the first study on pruning effects on growth habits and yield of TR.
Torrontés Riojano, Pruning, Horizontal trellis system, Vigor, Berry traits.
COP1 as a key redox-controlled regulator of hypocotyl growth under shade in plantsMaria Jose IglesiasIglesias MJ (1,2); Costigliolo Rojas C (1,3), Bianchimano l (1), Legris M(1), Schön J (4), Gergoff Grozeff GE (5), Bartoli CG (5), Blázquez MA (3), Alabadi D (3), Zurbriggen MD (4), Casal JJ (1,6)(1) Fundación Instituto Leloir and IIBBA-CONICET. (2) Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-UBA (3) Instituto de Biologίa Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientίficas, Universidad Politécnica de Valencia (4) Institute of Synthetic Biology and Cluster of Excellence in Plant Sciences, University of Düsseldorf (5) Facultades de Ciencias Agrarias y Forestales y Ciencias Naturales, Universidad Nacional de La Plata, CCT CONICET La Plata (6) Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomía, UBA, CONICETShade from neighbours enhance hypocotyl growth in Arabidopsis thaliana to increase the access to light. Reactive oxygen and nitrogen species (ROS and RNS, respectively) can function as signalling molecules in growth adjustment processes. However, it was suggested that shade could reduce the generation of ROS by the photosynthetic apparatus, alleviating their growth inhibitory effect. In contrast, we observed that shade triggered a more oxidative redox status in hypocotyl cells associated to the accumulation of superoxide anion, hydrogen peroxide and nitric oxide and the reduction in the glutathione pool. Seedlings affected in ROS and RNS accumulation genetically or pharmacologically, reduced the promotion of hypocotyl growth by shade, a response that required the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). Due to their reactivity, cysteine (Cys) residues are targets of a variety of post-translational oxidative modifications, including S-nitrosylation consolidated as a novel mechanism in physiological processes requiring a rapid and versatile regulation.  Shade-mediated redox changes favoured COP1 S-nitrosylation.  Mutation of a S-nitrosylated Cys reduced COP1 stability and capacity to interact with its targets, causing reduced biological activity under shade. Under field conditions, contrasting neighbour cues reach the plant from different angles. When exposed to these conflicting cues, COP1 mutant in S-nitrosylated Cys lost their vertical orientation making shade avoidance less efficient. These results place a COP1 as a key redox-controlled regulator cell growth promotion in an eco-physiological context.Arabidopsis, redox regulation, hypocotyl growth, shade
Role of proteins involved in miRNAs biogenesis in response to UV-B radiation in Arabidopsis thaliana plantsMaría Luján SheridanCasati, P (1)(1) Centro de Estudios Fotosintéticos y Bioquímicos, CEFOBI, ArgentinaUV-B radiation generates harmful effects on plants. Because of this, plants have developed multiple mechanisms of tolerance and adaptation to UV-B.

In proliferating leaves, the reduction in leaf area is in part a result of the inhibition of cell proliferation mediated by miR396, a microRNA that downregulates the expression of Growth regulating (GRFs) transcription factors. These TFs regulate numerous developmental processes acting redundantly. miR396 is expressed at low levels and increases during organ development, whereas GRFs are expressed in an opposite way. miRNAs are short RNA molecules that control gene expression at the post-transcriptional level by targeting the cleavage of complementary mRNAs or by inhibiting their translation. In plants, miRNAs precursors are transcribed by RNA polymerase II. Then, the endonuclease DCL1 participates in early stages of pri-miRNA maturation, while HYL1 and SE forms a nuclear complex with DCL1 for precise and efficient cleavage of pri-miRNAs. Finally, the nuclear protein HEN1 specifically methylates miRNA:miRNA* duplexes.

In this work, we analyzed the participation of HYL1, SE and HEN1, in the response of Arabidopsis thaliana roots to UV-B exposure. For this, plants were irradiated with UV-B during 1h 5 days after stratification, and then they were allowed to grow in the absence of UV-B. The studies were carried out using WT lines, and lines deficient in microRNA processing pathway (hyl1-2, se-1 and hen1-8). Root growth rate was analyzed by monitoring primary root elongation, and by means of confocal microscopy, analyzing the number of meristematic dead cells after exposure, and also the length and number of cells in the meristematic and elongation zones. The results show that all lines show differences in at least one of the parameters analyzed, indicating that proteins involved in the biosynthetic pathways of miRNAs modulate the response of roots to UV-B radiation, acting in the development of the meristematic zone.
UV-B radiation, roots, arabidopsis, miRNAs
Phenotypic patterns of vegetative-reproductive plasticity in maize inbred lines and their derived hybridsLutz, S.A. (1,2)Hisse, I.R. (1,4); Galizia, L.A. (1,3); López, C.G. (4,5); Maddonni, G.A. (1,2); D’Andrea, K.E. (1,2).(1) Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, C1417DSE Ciudad Autónoma de Buenos Aires, Argentina. (2) Instituto de Fisiología y Ecología Vinculado a la Agricultura, Consejo Nacional de Investigaciones Científicas y Técnicas (IFEVA-CONICET), Av. San Martín 4453, C1417DSE Ciudad de Buenos Aires, Argentina. (3) INTA Estación Experimental Agropecuaria Pergamino, Av. Frondizi (Ruta 32) km 4.5, B2700, Pergamino, Provincia de Buenos Aires, Argentina. (4) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. (5) Universidad Nacional de Lomas De Zamora (UNLZ). Camino de Cintura km. 2, (1832) Lomas de Zamora, Prov. de Buenos Aires, Argentina.Prolificacy and tillering in maize (Zea mays L.) are important sources of vegetative-reproductive plasticity, particularly in restrictive environments; however, the analysis of their plasticity patterns remains unexplored. We evaluated the phenotypic expression of 25 traits linked to vegetative-reproductive plasticity, and associations among them on a set of inbred lines and their derived hybrids. A field experiment was conducted during 2022-23 growing season at FAUBA, following a complete diallel mating design composed by six inbred lines of INTA Pergamino and their 15 derived single-cross hybrids (reciprocals excluded). For most traits, there were significant (P<0.05) differences between both genotypic groups (GG, inbreds vs. hybrids) and among individual genotypes into each GG, except for kernel number (KN) of the apical ear of inbreds (P=0.13). From a cluster analysis performed on five traits (grain yield (GY) of apical, subapical and tillers ears, and ear number of main stem and tillers) seven phenotypic groups (G) were identified: three formed by inbreds (G1: mainly flex= non-prolific-non-tillering, G2: prolific and G3: prolific-tillering), three by hybrids (G4a: highest potential GY and tillering, G4b: less potential GY and mostly flex, and G5: intermediate potential GY and prolific-tillering), and one by one inbred and one hybrid (G6: low potential GY and mainly tillering). The principal component analysis showed a differential response trend between both GG for traits correlated with GY. The GY of inbreds was associated with plant KN, sub-apical ear KN, prolificacy, and harvest index (HI) of main stem and tillers (r>0.80, P<0.05). Instead, GY of hybrids was associated with plant biomass and plant HI (r>0.80, P<0.001), as well as with GY and HI of tillers (r>0.73, P<0.01). These findings allow an understanding of the physiological bases of vegetative-reproductive plasticity and contribute to a more targeted selection process for restrictive environments.Zea mays, prolificacy, tillering, complete diallel experiment.
Streptomyces spp. alleviates drought stress in soybean plants, resulting in improved plant status and yieldMaldonado, R. A.1Iacomozzi, O.1; Villafañe, D. L.2; Bianchi, J. S.1; Rodríguez, E2 & Chiesa M. A11 Laboratory of Plant Physiology (LEFIVE) - IICAR-CONICET/UNR. Facultad de Ciencias Agrarias, Universidad Nacional de Rosario (UNR). Parque Villarino S/N, 2125, Zavalla, Santa Fe, Argentina. 2 Microbiology Division, IBR-CONICET/UNR, Ocampo y Esmeralda, 2000 Rosario, Argentina.Ver resumen adjunto.Abiotic stress, Glycine max (L.) Merrill, photosynthetic metabolism, water use efficiency
Soluble carbohydrates dynamics in wheat and rapeseed crops under shading, high temperature and its combination in post-floweringRivelli, Gonzalo MartínCalderini, D.F. (1); Abeledo (2,3), L.G.; Miralles D.J. (2,3); Rondanini, D.P. (2,3)(1) Instituto de Producción y Protección de Plantas, Universidad Austral de Chile, Valdivia, Chile. (2) Facultad de Agronomía Universidad de Buenos Aires, Buenos Aires, Argentina. (3) IFEVA, Universidad de Buenos Aires, Buenos Aires, Argentina.Stem soluble carbohydrates (CHS) in cereal and oilseed crops provide through remobilization an important source of assimilates during grain filling under abiotic stress conditions. However, little is known about the effects of combined abiotic stresses on the dynamics of wheat and rapeseed CHS. The aim of the work was to analyze the impact of the combined abiotic stress of high temperature and low incident radiation during the post-flowering period on the CHS dynamics of wheat and rapeseed. Field trials were conducted in a high (Valdivia, Chile; HYPE) and a low (Buenos Aires, Argentina; LYPE) yield potential environment, following a RCB design with 4 replicates. A spring wheat cultivar (Weebill) and a spring rapeseed hybrid (Solar CL) were evaluated. The treatments were: control (C), shading (S, -60% incident solar radiation), high temperature (HT, +5ºC during the midday hours) and combined stress of shading and high temperature (S+HT), using portable chambers placed in each plot during 10 days starting from 7 days after flowering in wheat and from 14 days after the start of flowering in rapeseed. In wheat, the concentration and content of CHS immediately after the stress were higher in the HYPE than in the LYPE for all treatments. The S (both environments) and S+HT (LYPE) treatments showed the lowest post-stress CHS concentrations in wheat. In rapeseed, the CHS concentration post-stress was contrasting between environments (7% higher in the HYPE than in the LYPE, average of all treatments). There were no differences in CHS concentration in rapeseed between treatments in any environment, while the CHS content only differed between S+HT and the control and S in the HYPE. In conclusion, the stress by shading (S and S+HT) provoked a significant reduction in the CHS concentration in wheat, in contrast to the greater stability observed in rapeseed.abiotic stress, environment, stem reserves, Brassica napus L., Triticum aestivum L.
SWEETs, MAX4, BRC1, and CLE44 genes are crucial players in the definition of Arabidopsis stem architecture impacting seed yieldRaminger, B.L.Chan, R.L.; Cabello, J.V.Laboratorio de Biotecnología Vegetal, Instituto de Agrobiotecnología del Litoral (UNL-CONICET), ArgentinaArabidopsis thaliana vascular pattern changes after weight application for a limited period. This strategy, generating an increase in stem diameter and the number of vascular bundles, allows identifying crucial players in stem architecture determination.
To elucidate the physiological and molecular mechanisms involved in such response, carbohydrates were evaluated in different organs of weight-treated plants. They accumulated more starch than controls in rosette leaves and showed a faster transport from source to sink tissues. These events can be explained, at least in part, by the induction of transcripts encoding SWEET transporters and enzymes participating in starch turnover.
Aside from auxin, previously shown as crucial for weight-response, brassinosteroids and strigolactones also play crucial roles. The mutants bes1 and bzr1 were insensitive to weight treatment, and the brassinosteroid inhibitor BRZ completely inhibited the response in wild-type plants. In addition, the max4 mutant, lacking a gene involved in strigolacotnes synthesis, neither responded to weight treatment.
Regarding genes participating from stem architecture, BRC1 encodes a transcription factor that negatively regulates branching and is regulated by BS and SL. BRC1 transcript levels increased after weight treatment, and bcr1 mutant plants did not change their number of vascular bundles after treatment. BRC1 induces CLE44 peptide expression, and this target was described as participating in proliferation and differentiation of procambial cells and in agreement, cle44 mutants were insensitive to weight treatment. Moreover, the treatment produced a decrease in sucrose transport to sinks and, as a consequence, a detriment in yield.
Together, these results indicated that the increase in seed production resulting from modifications in stem architecture and vascularization is a complex process requiring the joint action of multiple molecular and hormonal players.
vascular bundles, yield, CLE44, BRC1
Participation of lipooxigesases in ferroptotic cell death in Arabidopsis thaliana.Bauer, M. VictoriaDistéfano, A. (1); Pagnussat, G. (1); Zabaleta, E. (1)(1) Instituto de Investigaciones Biológicas, UNMdP, Argentina.Recently, we described an oxidative-iron dependent mechanism of regulated cell death (RCD), referred to as ferroptosis, due to its similarities to a mechanism previously reported in animals. We found that this type of RCD was induced by a 10-minute heat shock (HS) treatment (55°C) in Arabidopsis thaliana seedling root hairs. This RCD was inhibited by pre-treatment with the canonical ferroptosis inhibitors Fer-1 and CPX. This experimental system allowed us to determine that ferroptosis induced by HS it’s characterized by depletion of intracellular glutathione and ascorbic acid, accumulation of cytosolic and lipid reactive oxygen species (ROS), cytoplasmic retraction and mitochondrial shrinking. The molecular mechanisms behind plants ferroptosis it’s still highly unknown; here we studied the role of lipooxigenase (LOX) enzymes, that have a central role in the production of oxidized lipids in animals ferroptosis. We analyzed the effect of a LOX inhibitor, Baicalein (Bai), in ferroptosis cell death in roots of Arabidopsis seedlings induced by a heat treatment (HT) of 45°C during 1h. In addition to this we studied the behavior of 4 lines of LOX mutants (LOX1, LOX3, LOX4 and LOX6) upon HT. The LOX inhibitor Bai it’s capable of preventing this type of RCD and LOX mutants are more resistant to ferroptosis induced by HT than WT plants. Also, it might exist functional redundancy between the different LOX isoforms. Our results suggest that LOX enzymes are involved and required for plant ferroptosis.ferroptosis, lipooxigenases
Dormancy release or viability loss? The fate of Lolium multiflorum Lam. seeds depends on temperature and seed water content.Lucas Agustin Royo Simonella (1)Canchero, J. O. (2); Batlla, D. (3)(1) Cátedra de Cerealicultura, FAUBA, Argentina. (2) Facultad de Agronomía, UBA, Argentina. (3) Cátedra de Cultivos Industriales, FAUBA-CONICET, Argentina.Primary dormancy release and gradual viability loss occur simultaneously in Lolium multiflorum seeds, resulting in transient seed-banks. The rate at which both processes occur is regulated by temperature and seed water content. The objective of this work was to quantify the effect of seed water content and temperature on the rate of primary dormancy release and viability loss in L. multiflorum seeds. For this purpose, seed water content at harvest was modified by drying or wetting the seeds for increasing times. Six seed water content (SWC) conditions were obtained: 8, 10.5, 13.3, 18, 20.6, and 23.5%. The seeds were then placed in airtight cryovials and stored in the dark at: 15, 20, 25, 30, 35, 40°C (for seeds of 8, 10.5, 18, 20.6 and 23.5% SWC) and 5, 10, 15, 15, 20, 25, 30, 35, 40 and 50°C (for seeds of 13.8% SWC). Every 30 days during a 3-month storage period, the following were quantified: a) seed water content, b) seed dormancy level by germination tests at 15 and 20°C, and c) viability of non-germinated seeds by tetrazolium test. The results showed that L. multiflorum seeds maximized primary dormancy release at low SWC (<10.5%) and high temperatures (>25°C). On the other hand, temperatures >25°C and SWC >18% caused viability loss of 20 to 100% of the seeds in a short period of time (30 to 90 days). The information generated in this work can be used to improve the predictive capacity of emergence models of this weed by including the effect of temperature and seed water content on two key processes that regulate seed emergence (seed dormancy and seed viability). Furthermore, this knowledge may be useful in developing agronomic practices that promote L. multiflorum seed-bank viability loss (i.e., seed-bank depletion practices).Italian ryegrass, seed longevity, seed-bank, predictive models of emergence
Morphological plasticity of sunflower in response to light availability and carbohydrate accumulation with special attention paid to fructans.Dosio, G.A.A.García, L.A. (1,2); Martínez-Noël, G.M.A. (3); Giorgi, M.E. (4); Tognetti, J.A. (1,5); Dosio, G.A.A. (1,2)(1) Instituto de Innovación para el Desarrollo Agroalimentario y Agroenergético Sostenible (IIDEAGROS), Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Argentina. (2) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. (3) INBIOTEC and FIBA, Mar del Plata, Argentina. (4) Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), CONICET, Universidad de Buenos Aires, Argentina (5) Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), Argentina.Changes in plant structure may define plant capacity to synthesize and accumulate soluble carbohydrates that will ultimately contribute to grain filling in sunflower, via actual photosynthesis or previously stored reserves. The present work is aimed at studying the relationship between light-driven changes in organ size and sugar accumulation in this species, with special attention to fructans formation. We performed three field experiments with three sunflower genotypes under contrasting irradiance or capitulum removal treatments. We analyzed growth parameters and the dynamics of production and distribution of soluble carbohydrates in plant organs.
Increasing light availability from shaded to control treatment induced a moderate enhancement of storing organs volume and an increase in soluble carbohydrates concentration. In contrast, when light availability increased from control to thinned treatment a strong growth promotion with no increase in sugar concentration was observed.
Carbohydrates analysis of capitulum tissue at the highest light availability revealed, for the first time in this species, the presence of inulin-type fructans. The amount of each member of the series appeared to decline starting from isokestose, being DP = 15 the longest fructan detected. Results suggest that, in sunflower, fructans could be synthesized only when sucrose availability exceeds a high threshold. The dilution of sucrose under usual field growing conditions would prevent the induction of fructan metabolism.
Given the relationship between fructans and tolerance to abiotic stresses including drought, the present finding opens a new perspective for breeding and management of this crop.
Both light and carbohydrates per se affected the plastic growth response of organs, which was independent from genetic background and may directly impact on plant capacity to store sucrose, ultimately conditioning crop yield under stress.
capitulum, carbohydrate reserves, Helianthus annuus, high irradiance, organ plasticity, sucrose, inulin-type fructans
Soil moisture levels affect nodule development in field pea (Pistum sativum L).Delfina ReMichel, Analia (1,2); Caviglia, Octavio Pedro (1,2); Ré, Delfina Adela (1,2)(1)Facultad de Ciencias Agropecuarias, Universidad Nacional de Entre Ríos. (2)CONICETLegumes form symbiotic associations with microorganisms, particularly with Rhizobium and Bradyrhizobium genera, to fix atmospheric nitrogen (N) and cover a significant portion of their crop N requirements. In the province of Entre Rios, Argentina, most soils have a fine texture and low aeration capacity, which may impact biological nitrogen fixation, especially in waterlogging-sensitive species like Pisum sativum L. While it is known that stress can affect nodule establishment and nodulation, little information exists regarding the impact of this stress after nodules have already been established, which is the focus of our project. 

We grew P. sativum plants in a greenhouse under three different irrigation frequencies, leading to three different water moisture on the pots. We then analyzed different parameters of plant development, finding interesting results on final nodules morphology and distribution. When compared plants grew under different irrigation frequencies, we observed that nodule number did not correlate with nodule weight, indicating that individual nodule size varies between treatments. We also found differences in the final morphology of the nodules, depending on de irrigation treatment applied.

Our results clearly evidended an important impact of different irrigation frequencies applied to P. sativum plants affecting the nodule number, size and morphology. Our future research will focus on investigating the morphology and functioning of field pea nodules, aiming to provide comprehensive insights into their role in nitrogen fixation under different soil moisture conditions.
Legumes, stress
OsOXR-Q12 protein is involved in cellular defense homeostasis and contributes to salt stress tolerance in Oryza sativaEvelyn Becerra-AgudeloWelchen, Elina (1)Instituto de Agrobiotecnología del Litoral (IAL-CONICET-UNL). Cátedra de Biología Celular y Molecular (FBCB-UNL).In rice plants (Oryza sativa var. Kitaake) with increased ectopic expression of AtOXR-Q12 chimeric protein (oeOsOXR-Q12 plants), significant improvements were observed in phenotypic parameters like plant biomass, root development, and salt stress tolerance when compared to Kitaake (WT). Furthermore, oeOsOXR-Q12 plants demonstrated elevated levels of H2O2 and lower O2.- content, as evidenced by DAB and NBT staining. Catalase activity was reduced, while the levels of superoxide dismutase, glutathione oxidase, phenols, and flavonoids were found to be basally increased compared to WT plants under normal growth conditions. Additionally, stress-marker genes such as HKT1, SOS1, PEX11, and SERF1 were differentially and beneficially expressed in oeOsOXR-Q12 plants, further strengthening their salt-stress tolerance phenotype.

Stress is generally associated with ROS (Reactive Oxygen Species). ROS do not disrupt the redox balance at certain levels but could alter the homeostasis of auxins, abscisic acid, and gibberellins. Interestingly, these hormones counteract the effects of brassinosteroids (BR). In this sense, we found a downregulation in the synthesis and accumulation of genes like BRD1 and BZR1 and an upregulation of the repressor gene GSK2. These gene movements were associated with lower BR concentration and were connected to the reduced lamina joint angle observed in 8-day-old oeOsOXR-Q12 rice seedlings. We can confidently conclude that the increase in H2O2 generated by oeOsOXR-Q12 is related to the hormonal balance, which results in a range of adaptive traits that enhance stress tolerance.
OXR, Salt stress, Homeostasis, ROS, Hormonal balance, rice.
RPL10A promotes plant tolerance to drought and salt stressesPetrich, J.Ramos, R.S.; Casati, P.; Spampinato, C.P.; Falcone Ferreyra, M.L.Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI, CONICET-UNR)Ribosomal proteins are not only involved in translation, but also, in plant response to abiotic stress. We have previously demonstrated that RPL10A plays a role in UV-B radiation stress and in ABA-dependent responses, acting as a positive regulator. Therefore, we here aimed to investigate the contribution of RPL10A in conferring drought and salinity tolerance in Arabidopsis thaliana plants. First, we performed seed germination assays at 100 mM NaCl and observed that RPL10A-overexpressing plants (RPL10A-OEs) germinated later than wild type (WT) plants. However, the growth response of RPL10A-OE and WT plants to salt stress was inversely correlated with germination. At 21 days after sowing, RPL10A-OEs plants showed higher survival rates than WT plants (60% and 32%, respectively), with more leaves remaining green. Moreover, RPL10A-OEs exhibited less inhibition of the primary root elongation by salt stress, less decrease of fresh shoot and root weights per seedling, less electrolyte leakage and higher chlorophyll content respect to WT plants. In addition, RPL10A-OEs showed a better performance than WT plants under drought conditions. The addition of mannitol at the seedling stage caused a less relative inhibition of primary root elongation of RPL10A-OE compared to WT plants (50% versus 64% at six days after transfer to medium with mannitol). The withholding water of 21-days-old plants for seven days displayed a higher tolerance of RPL10A-OE lines (60% survival) compared to WT plants (17% survival). Other parameters such as proline levels and oxidative damage to membranes are now being determined. In conclusion, these results show that the delayed germination of RPL10A-OE may be considered as a protective strategy to ensure maximal survival under osmotic stress, thus suggesting an additional role of RPL10A in plant tolerance to abiotic stress.ribosomal protein L10, osmotic stress, salinity, drought, Arabidopsis
Nuclear-SnRK1 localization improve salt stress tolerance responsesLando, Ana Paula (1)Barbieri, G. (2,3); Nome, C. (4); Martínez-Noël, G. (1); Rodriguez, M (2,3)(1) Instituto de Investigaciones en Biodiversidad y Biotecnología (INBIOTEC-CONICET). Fundación para Investigaciones Biológicas Aplicadas (FIBA), Mar del Plata, Argentina. (2) Unidad de Estudios Agropecuarios (UDEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina. (3) Instituto de Fisiología y Recursos Genéticos (IFRGV), Centro de Investigaciones Agropecuarias (CIAP), Instituto Nacional de Tecnología Agropecuaria (INTA), Córdoba, Argentina. (4) Instituto de Patología Vegetal (IPAVE), Centro de Investigaciones Agropecuarias (CIAP), Instituto Nacional de Tecnología Agropecuaria (INTA), Córdoba, Argentina.Salinization has long been known as a common environmental problem worldwide which directly affects photosynthesis and crop yield. Because of this, adaptation of metabolism and growth to adverse environmental conditions is essential to maintain cellular homeostasis and, therefore, organism survival. In this context, we studied the SnRK1 kinase which plays a central role to maintain energy and metabolism homeostasis, as a regulator of signaling networks for stress tolerance responses in plants. The aim of this work was to evaluate the impact of subcellular localization of SnRK1α-subunit (nuclear or cytosolic) in ultrastructure cell, chloroplast function, dry biomass in plants under salt stress. We evaluated cellular ultrastructure (TEM) and chlorophyll fluorescence (ChlF) in transgenic plants with forced SnRK1α-subunit localization (NLS- nuclear localization or MYR- cytosolic localization) and Wild-Type (Col-0) subjected to NaCl treatments. Results showed that NLS plants subjected to salt stress had cells with more organelles such as mitochondria and peroxisomes in relation to MYR-plants. NLS-mitochondria showed change in the morphology with shape cupped. MYR-chloroplasts presented structural distortion and possessed swollen thylakoids and poorly developed stroma. This phenotype was reflected in the ChlF analysis of MYR-plants, showing heat energy dissipation (NPQ, qL), changes in thylakoid electron transport with lower proton conductivity (LEF, gH+) in the principal components analysis. Interestingly, at the end of experiment, NLS-plants subjected to salt conditions maintained similar dry biomass to the ones without stress and showed Na/K decrease in relation to MYR-plants. Overall, the results reveal key roles for nuclear SnRK1 in response to tolerance to NaCl stress.

Financial support: PICT2019-02118; PIP-1701; PICT2021-00229; INTA I116; INTA I084
Arabidopsis, SnRK1, Stress tolerance, Cellular ultrastructure, Chlorophyll fluorescence
Molecular mapping of the Rdm3 locus controlling local isolates of Diaporthe aspalathi. Analysis of its presence in Argentinian soybean varietiesChiesa M. A.Maldonado, R. A.; Moser, V.; Bianchi, J. S.Laboratory of Plant Physiology (LEFIVE) - IICAR-CONICET/UNR. Agronomy Faculty, National University of Rosario (UNR). Parque Villarino S/N, 2125, Zavalla, Santa Fe, Argentina.Diseases represent one of the major problems that severely limit crops productivity and seeds quality, resulting in significant yield losses every year worldwide. One of the most effective alternatives to mitigate these losses is the use of genotypes with genetic resistance to different pathogens. This approach offers a sustainable way to reduce pesticides usage and enhance plant health without resorting to transgenesis. Diaporthe aspalathi (Da), one of the causal agents of soybean stem canker (SSC-Da), is a pathogen with phytosanitary impact worldwide and present in the core soybean region of Argentina. Five major dominant non allelic genes (Rdm1 to Rdm5) confer resistance to SSC-Da. The objectives of this study were to: (i) assess the efficacy of the Rdm3 gene, present in cv. Crockett, in conferring resistance against two local isolates of Da; (ii) map the Rdm3 gene in the soybean genetic linkage map and identify flanking molecular markers (MM) useful to MM-assisted breeding; and (iii) analyze its presence in a set of cultivars (cvs) extensively sown in this region, in comparison to the presence of the previously mapped Rdm4 gene. As results, Rdm3 behaved as a single dominant gene in the interaction with both local isolates of Da in progeny tests. Then, the Rdm3 gene was located in the molecular linkage group B2 (chromosome 14, Gm14) and the MMs BARCSOYSSR_14_0080 and BARCSOYSSR_14_0117 were identified flanking the gene in a physical interval of 684660 base pairs (bp). From the 47 cvs. genotypically analyzed with the flanking MMs, only one presented both MMs linked to Rdm3, while four genotypes presented only one of the MM. Meanwhile, 43 cvs. were found to carry the Rdm4 gene. In conclusion, Rdm3 is a major and broad spectrum gene that confers resistance to widely geographic separated isolates from the soybean core zone of Argentina. Therefore, it is key to stack these genes (Rdm3/Rdm4) in commercial genotypes to confer a more durable and broader resistance to SSCbiotic stress, genetic resistance, gene mapping, Glycine max (L.) Merrill, molecular assisted breeding
Role of auxin signaling in root hair growth at low-temperature in Arabidopsis thalianaVictoria Berdion Gabarain (1)Ramirez Silva C. (1), Estevez J.M (1,2,3)(1) Fundación Instituto Leloir and IIBBA-CONICET, Av. Patricias Argentinas 435, Buenos Aires, Argentina. (2) Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile. (3) ANID - Millennium Nucleus for the Development of Super Adaptable Plants (MN-SAP), Santiago, Chile.

Root hairs (RH) serve as an exceptional model system for studying how plants regulate growth, influenced by a combination of cell-intrinsic factors, such as hormones, and external environmental signals like nutrients. The auxin effect in RH growth depends on the systemic auxin metabolism concentrated mostly on the meristem-root cup, intercellular auxin transport via root epidermis and on-site RH signaling. In our lab, we realized middle low-temperature switching experiments using A. thaliana accessions at 10°C. These experiments revealed a significant three-fold increase in root hair (RH) growth compared to RH elongation observed in the control temperature (22°C). To know if the auxin pathway is involved in the growth response of RH at low-temp, we identified which are the genes in A. thaliana annotated that are involved in the different aspects of auxin pathway: auxin biosynthesis, conjugation, transport and signaling. In this work, we collected data demonstrating that auxin affects the molecular mechanisms that lead to exacerbated the development of RH at low-temp by analyzing numerous mutant plants in the auxin biosynthesis (sav3, yucca t, yucca q mutants), transport (pin2, aux1, pgp4), and signaling pathway (ARF and AFB family, tir1). In addition, when we use an inhibitor of the IAA biosynthesis pathway, it is observed that the response to low-temp is affected. Finally, our characterization of auxin signaling reporters (pDR5::GFP and 35S::DII-Venus) confirmed the reduction of the auxin signal in the root tip during the treatment at low temperature while there is an increase in the signal of an auxin efflux transporter (pPIN2::PIN2-GFP). Overall, these results uncover the auxin pathway as being one central hub under low temperature in the roots to trigger RH growth. Low temperature stimulus comprises complex nutritional signals coming from the media-soil into the roots that may be fine-tuned for future biotechnological applications to enhance nutrient uptakes.

auxin, root-hair, low-temperature
Identification of the regulatory network controlling root hair growth under inorganic phosphate deficiency and high salinity in Arabidopsis thalianaJose M. EstevezMiguel Angel Ibeas1,2,3, Isidora Venegas1,2,3, Juan Manuel Peralta2,4, Tomás Moyano1,3, Nathan Jhonson3,5, Aníbal Riveros2,7,8, Hernán Grenett-Salinas1,3, Tomás Urzúa Lehuedé1,2,3, Romina Acha-Escobar1,2,3, Thomas Muñoz-Duman1, Elena Vida3,5,6, José Miguel Álvarez1,3, Claudio Meneses2,5 and José Manuel Estévez1,2,3,41 Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile. 2 ANID-Millennium Science Initiative Program – Millennium Nucleus for Development of Super Adaptable Plants (MN-SAP), Santiago, Chile. 3 ANID-Millennium Science Initiative Program – Millennium Institute for Integrative Biology (iBio), Santiago, Chile. 4 Fundación Instituto Leloir and IIBBA-CONICET, Buenos Aires, Argentina. 5 Centro de Genómica y Bioinformática, Facultad de Ciencias, Ingeniería y Tecnología, Universidad Mayor, Santiago, Chile 6 Escuela de Biotecnología, Facultad de Ciencias, Ingeniería y Tecnologiìa, Universidad Mayor, Santiago, Chile 7 Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile 8 Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, ChilePlant growth is conditioned by several stresses from drought, salinity, changes of temperature, and variable levels of nutrients. Although the impact of individual stresses has been researched, in field conditions several of them might affect plant growth at the same time. Nowadays, to understanding these multi-stress interactions have become critical to achieve sustainable agriculture in a context of global climate change. Root hairs (RH) have a vital implication for plants as they determine the surface/volume ratio of their roots exposed to water and nutrients reserves in soils. Nevertheless, the molecular mechanisms controlling RH growth under multiple abiotic stresses are still unknown. We explored the link between two abiotic stresses (phosphate (Pi) starvation and high salinity) and their impact on RH growth using different approaches. It is known that two transcription factors, PHOSPHATE TF1 (PTF1) and PHOSPHATE TF2 (PTF2), control the low Pi response in roots but it is still unknown how they operate at the RH level. Our research made use of RNAseq, GWAS and data mining approaches in order to identify novel key genes required to regulate RH growth under low Pi with high salinity. Our understanding of how these two-stress act at the molecular level may help us to develop super adaptable crops. Our results suggest that PTF1 could be important to respond to these multi-stress conditions as mutants showed inhibition of RH growth in low Pi/high salinity treatment. RNAseq experiments allowed us to identify early responsive genes networks dependent on PTF1 and PTF2 in low pi and high salinity conditions, while data mining analysis allowed us to identify TFs that could be important to stablish responses to these multi-stress conditions.Arabidopsis, data mining, gene regulatory network, GWAS, phosphate starvation, root hairs, Tomato, salt stress, super adaptable plants
Identification and characterization of ATPase II-A type Ca+2 transporter systems (ECAs) involved in polar cell expansion of root hairs.Gabriela Díaz DomínguezEstevez, J.M. (1,2)(1) Fundación Instituto Leloir and IIBBA-CONICET, Argentina. (2) Centro de Biotecnología Vegetal (CBV), Facultad de Ciencias de la Vida, Universidad Andrés Bello, ChilePIIA type Ca2+ ATPases (ECAs) make up a family of four proteins (ECA1-ECA4) found in the membranes of the endoplasmic reticulum, Golgi apparatus and vacuoles of plant cells. In Arabidopsis thaliana root hairs, ECAS regulate calcium homeostasis, favouring the polarized growth of these cells. Studies with different simple mutants for each of them, showed that some of these ECAs have redundant functions and that the deficiency of others produces a decrease in the length of the root hairs. On the other hand, a pharmacological inhibition study was carried out with CPA (cyclopiazonic acid), which is an inhibitor of the homologous protein in mammalian cells, and root hair shortening was observed. Low temperature conditions generally promote greater growth of root hairs, so it might be thought that in plants inhibited with CPA and subsequently subjected to low temperatures, root hair growth would be at least partially rescued.ECAs, calcium homeostasis, root hairs, low temperature
Plant responses to far-red supplementation and photosynthetically active radiation in an olive cultivar common to super high-density orchardsLadux, F.J. (1,2)González, C.V. (3, 4); Trentacoste, E.R. (5); Searles, P.S. (1); Rousseaux, M.C. (1, 2)(1) Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-Provincia de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET), Entre Ríos y Mendoza s/n, Anillaco 5301, La Rioja, Argentina (2) Departamento de Ciencias Exactas, físicas y Naturales (DACEF y N), Universidad Nacional de La Rioja, Av. Luis M. De la Fuente s/n, Ciudad Universitaria de la Ciencia y de la Técnica, La Rioja 5300, La Rioja, Argentina. (3) Instituto de Biología Agrícola de Mendoza (IBAM), FCA UNCuyo – CONICET, Almirante Brown 500, Chacras de Coria (5505) Luján de Cuyo, Mendoza, Argentina (4) Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo, Almirante Brown 500 (5528) Luján de Cuyo, Mendoza, Argentina (5) Estación Experimental Agropecuaria La Consulta (Instituto Nacional de Tecnología Agropecuaria), Mendoza, ArgentinaCultivation of olive trees in super high-density (SHD) hedgerows leads to a rapid increase in photosynthetic leaf area and crop yield, but also increases shading within and between trees. Such canopy shading reduces both photosynthetic active radiation (PAR) and red-to-far red ratio (R/FR). The objective of this study was to assess plant morphology, biomass, and photosynthetic pigment responses to different PAR and R/FR combinations in an olive cultivar (Arbequina) common to SHD hedgerows. The four experimental combinations were low (L) or high (H) PAR with either supplemental lateral FR (+FR) or no FR supplementation (-FR). The L and H treatments were obtained using either a 25% transmittance shade cloth or 90% transmittance netting, respectively. The lateral FR supplementation was applied to individual plants using light-emitting diodes that reduced the R/FR ratio from about 0.90 to 0.25. The internode length and main stem elongation were lower under L than H, and were higher in L+FR than L-FR. Axillary shoots were more vertically-oriented under L+FR than the other treatments, while leaf angle was more vertical with +FR at both PAR levels. Based on a principal component analysis of all the measured variables, the +FR plants did not differ from -FR under H, but they did differ from -FR under L. These findings suggest that young, cv. Arbequina olive trees do not anticipate imminent shading when PAR is still high through early low R/FR signals. However; different plant morphology, architecture and photosynthetic pigment traits were modified that could affect light absorption and penetration into the hedgerow later in orchard development when low PAR through direct shading is prominent.Olea europaea L., Arbequina, light intensity, red-to-far-red ratio, shade
Identification of genes involved in salinity tolerance in a collection of alfalfa insertional mutantsCintia JozefkowiczFernández, K. (1), Gómez, C. (1), Ayub, N. (1,2), Soto, G. (1,2), Jozefkowicz, C. (1,2)(1) Laboratorio de Ingeniería Genética de Leguminosas, Instituto de Genética (IGEAF) gv IABIMO, INTA, Buenos Aires, Argentina. (2) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.The aim of this work is to identify and characterize new genes associated with salinity tolerance using as a tool a collection of alfalfa (Medicago sativa) mutants that was previously generated in our group through the insertion of the Tnt1 tobacco retrotransposon.

To carry out this objective we generated a large collection of mutant lines of Medicago sativa (alfalfa) by activation and transposition of the Tnt1 retrotransposon, from eleven primary transgenic lines (T0) that carry the Tnt1 retrotransposon in alfalfa clones that have good in vitro behavior. By passage through in vitro culture, Tnt1 retrotransposon activates and transposes to new random sites in the alfalfa genome. From eight plants that were molecularly characterized (R1 plants), we generated 153 independent lines (R2 plants) representing an estimated 16000 insertion events in the alfalfa genome, after a second passage through tissue culture. We know insertions are inherited and stable during vegetative growing of alfalfa and in subsequent generations. We crossed Tnt1 mutant lines with elite varieties of alfalfa and performed salinity tolerance assays, during the germination stage and during the implantation stage in hydroponic culture. So far, we selected three mutant lines for their ability to germinate in elevated concentrations of NaCl. Subsequently, we will determine the number of Tnt1 insertions in these lines which show a differential phenotype of salinity tolerance and we will identify the genes that have been repressed or over-expressed by Tnt1 insertion by Inverse PCR (Jozefkowicz et al., 2021).

In biotechnological terms this platform represents a powerful tool for the direct identification of new dominant mutations associated with desirable agronomic traits that can be phenocopied using transgenic-free edited cultivars via the CRISPR/Cas9 system in  major crops with complex genetics, like alfalfa.
alfalfa, salinity tolerance, dominant mutation, Tnt1 retrotransposon
The miR390/TAS3/ARF pathway governs expression of an LBD member to regulate root nodule symbiosis and root architecture in Medicago truncatulaMaria Eugenia ZanettiCristina Kirolinko(1), Karen Hobecker (1), Marianela Cueva(1), Florencia Botto (1), Aurelie Christ, (2) Andreas Niebel (3), Federico Ariel (4), Flavio Blanco (1), Martín Crespi(2)(1)Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Científico y Tecnológico-La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, La Plata, Argentina. (2) Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, France. (3) Laboratoire des Interactions Plantes-Microorganismes, Université de Toulouse, INRAE, CNRS, Tolosan, France. (4)Instituto de Agrobiotecnología del Litoral, Universidad Nacional del LitoralThe microRNA390 targets the TAS3 transcript leading to the production of trans-acting small interfering RNAs (tasiRNAs), which in turn post-transcriptionally repress the mRNAs encoding the Auxin Response Factors (ARFs) 2, 3 and 4. This pathway has been involved in the development of lateral organs in both aerial and underground tissues. Previously, we have shown the miR390/TAS3/ARFs pathway mediates the development of lateral roots and symbiotic nodules in legumes. More recently a transcriptomic study of Medicago truncatula miR390 overexpressing roots revealed that a member of the Lateral Organ Boundaries Domain (LBD) family of transcription factors is controlled by this pathway. A phylogenetic analysis revealed that this member of the LBD family is evolutionary related to LBD17 and LBD29 from Arabidopsis, thus we named it as MtLBD17/29. RNA-seq, RT-qPCR and promoter fusion analyses revealed that MtLBD17/29 is induced under symbiotic conditions, but not in miR390 overexpressing roots or in roots that have been silenced in ARF2/3/4. ChIP-PCR experiments demonstrated that MtLBD17/29 is a direct target of MtARF2. Knockdown of MtLBD17/29 produced a significant reduction in the number of nodules and infection events and impaired the induction of the symbiotic genes Nodulation Signalling Pathway (NSP) 1 and 2, reminiscent of the phenotype observed in ARF2/3/4 silenced roots. In addition, knockdown of MtLBD17/29 altered root architecture reducing the length of primary and lateral roots but increasing the density of lateral roots. These results suggest that MtLBD17/29, which has been involved in lateral root development in nonlegume species (i.e., Arabidopsis and tomato), has been recruited in legumes to mediate the root nodule symbiosis, as previously described for other member of the LBD family of transcription factors.Auxin, Lateral Organ Boundaries,Llegumes, Symbiosis, Transcription Factors
New approaches on source-sink relationships in maize: nitrogen accumulation during kernel development and effects on kernel weightMariana AntoniettaSaric R. (1), Dominguez H. (1), Fanello D.D. (1), Maydup L.M. (1), Guiamét, J.J. (1)(1) Instituto de Fisiología Vegetal, INFIVE, CONICET- Universidad Nacional de La Plata.Traditional approaches on source-sink relationships in maize estimate the sink by the number of fixed kernels. However, recent works suggest that kernel nutrient status plays an important role determining sink strength. To explore this, a field experiment with two N levels (70 vs. 200 kg N ha-1) and four hybrids (SYN840 vs. SYN860, and  DK72 vs. DK73) was conducted in La Plata, Buenos Aires, to compare kernel C and N accumulation during grain filling. Kernel samples were taken at 20, 38 and 60 days after silking (DAS). Yield was reduced by 38% at low N level, due to both reductions in kernel number (-25%) and kernel weight (-17%). Between hybrids, yield reduction was larger in SYN840 (-42%, vs. -35% in SYN860) and DK72 (-41% vs. -35% in DK73). Decreased N level significantly reduced kernel %N, with N x stage interaction showing lowest reductions at 60 DAS and hybrid x stage interaction indicating that hybrid differences were accentuated at early and mid-developmental stages. At 20 DAS, lowest %N was detected in SYN840 (1.23% vs. 1.38% in SYN860) and in DK72 (1.32 vs. 1.53%) whereas at 38 DAS the same trend was maintained (1.06% vs. 1.24% in SYN840 and SYN860; 0.96 VS. 1% in DK72 and DK73). The concentration of soluble sugars in kernels (a possible proxy of failures in C metabolism) was higher at low N, especially in SYN840 (+34% vs. -18% in SYN860) and DK72 (+11% vs. 3.6% in DK73). Across hybrids, yield was positively related to %N in kernels at stages I and II (r2=0.38*** and r2=0.60***, n=32). These results show that (i) %N in kernels at harvest is not a good proxy of N status during kernel development; (ii) hybrid trends in %N in kernels are not maintained across N levels; (iii) low %N in kernels at early stages of development relate to higher soluble sugar concentration. These results suggest that in some situations, %N in kernels could be below those required to optimize kernel carbon metabolism.Maize, nitrogen, kernel, development, metabolism
STUDY OF THE TRANSCRIPTIONAL REGULATION OF GENES INVOLVED IN ENDOCYTIC VESICULAR TRAFFIC BY A WRKY TRANSCRIPTION FACTOR INDUCED DURING RESPONSE TO SALSAYONARA PLATA ARBOLEDARuiz-Lara, S.Instituto de Ciencias Biológicas, UTalca, Talca, Chile.Soil salinity restricts water and nutrients uptake and causes ionic toxicity to the plants. Sodium compartmentalization in the vacuole is an essential response during salt stress, and this is partially mediated by endocytic vesicular trafficking (EVT). Different proteins are currently known to be involved in directing EVT to the vacuole during the salt stress response, whose genes are induced by salt. To date, the posttranslational regulation of these proteins has been extensively investigated, but no transcriptional regulation. This research set out to identify  transcription factors (TF) that regulate genes involved in EVT that contribute to sodium compartmentalization in the vacuole during salt stress. Previously, a WRKY TF was selected by several bioinformatics analyses as Evaluation of spatiotemporal gene expression under salinity conditions and the comparison of homolog expression between salt stress sensitive and salt stress tolerant species. The promoter sequences of 5 genes related to EVT were analyzed in search of cis-elements to binding of TF WRKY. Next, 18-day-old Arabidopsis thaliana plants of wild-type genotype were submitted to a salt stress treatment and the expression of EVT-related genes was evaluated by qPCR. Agrobacterium tumefasciens strains were utilized to assess protein-DNA binding by transient cotransformation of Nicotiana benthamiana leaves. One strain with the WRKY CDS under the control of the 35S promoter, while other strain included one of the EVT gene promoters binded to the GUS reporter. Histochemical tests and qPCR was used to examine GUS activity and transcription. The rate of internalization of the indicator FM4-64 was measured to examine the rate of EVT in roots of wild-type and mutant for WRKY seedings. The results showed that this WRKY TF positively regulated the transcription of 3 of the genes evaluated. Furthermore, plants mutant for this TF showed a significantly lower EVT level under saline conditions than wild-type plants.WRKY, Salt stress, endocytic vesicular trafficking.
Interaction of ascorbic acid and gibberellins in the establishment of tomato fruitsMatias Leonel AlegreBaldet P. (2); Rothan C. (2); Bres C. (2); Just D (2); Okabe Y. (3,4); Ezura H. (3,4); Gergoff Grozeff G. E. (1); Bartoli C.G. (1)(1)INFIVE, Facultades de Ciencias Agrarias y Forestales y Ciencias Naturales, Univ Nac de La Plata-CCT CONICET La Plata, Argentina. (2) Fruit Biology and Pathology Research Unit, INRA, Bordeaux, France. (3) Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan. (4) Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Japan.Tomato fruit have a great economic and nutritional importance for human beings. The number of fruits per plant is the most important factor determining the yield of tomato crops. This factor depends on the efficiency of fruit set and is a consequence of successful pollination and fertilization. Gibberellins (GA) have been found to play a very important role in promoting pollen tube growth and the onset of fruit growth. Tomato mutants (slggp1) deficient in GDP-L-galactose phosphorylase activity, a key enzyme in the ascorbic acid (AA) synthesis pathway, have lower GA concentrations in the flowers and a lower percentage of fruit set. AA plays a central role in the antioxidant defense of plants and numerous other functions, among which we will highlight its role as an enzymatic cofactor in the synthesis of GA and its participation in the regulation of cell division and expansion. To determine the mechanisms and signals triggered by GA and AA in fruit set and pollen grain growth, slggp1 mutants deficient in AA and a wild type were used. These plants were periodically sprayed with GA3 and paclobutrazol (PBZ, an inhibitor of GA synthesis). The PBZ treatment decreased the percentage of fruit set in the mutant genotypes but not in the wild type plants and the GA treatment increased the percentage of fruit set, similar in both mutant and wild type. The pollen tubes of the mutant genotypes have a lower in vitro growth rate. The GA content (GA1, GA3, GA4 y GA8) as well as the expression of key genes in the gibberellin synthesis, degradation and signaling mechanism were analyzed in gynoecia of pre-anthesis, anthesis flowers, and 2-4 mm fruits. From these preliminary results, it can be assumed that there is an interaction between a signaling molecule such as GA with AA levels, which could be a new contribution to the complex signaling process involved in the establishment and initiation of fruit growth.ASCORBIC ACID, FRUIT SET, TOMATO
Phenology and biomass production responses of malting barley to inoculation with Azospirillum argentinenseMariana L. Puente (2)Martinez C. (1); Ibarra, L.S. (3); Criado, M.V. (1)(1) Cátedra de Microbiología Agrícola. Facultad de Agronomía. Universidad de Buenos Aires. INBA-CONICET-FAUBA. Buenos Aires, Argentina. (2) Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Microbiología y Zoología Agrícola, Buenos Aires, Argentina (3) Cátedra de Granos y forrajes, y Centro de Estudio para el Desarrollo de la Agricultura Familiar (CEDAF). Facultad de Ciencias Agrarias. Universidad Nacional de Jujuy. S.S. de Jujuy, Argentina.To achieve high yields in barley (Hordeum vulgare L.), it is essential to establish an adequate green leaf tissue during development, capable of achieving the highest possible uptake of incident radiation and thus generate an optimal production of photoassimilates, which will then be translocated to the grain. The objective of this work was to analyze the effect of the inoculation of the Azospirillum argentinense Az39 strain in malting barley on parameters that establish the green leaf area such as the appearance, number and size of leaves and tillers, as well as on its development cycle in a context of sustainable agriculture. For this purpose, barley plants of the Andreia variety were grown in a greenhouse at FAUBA and inoculated or not with the Az39 strain (Az- and Az+ plants). Inoculation with this strain modulated the leaf dynamics of the plants since Az+ plants showed higher leaf emergence rate and lower phyllochron, higher final number of leaves and higher area and dry weight of each leaf level when compared to Az- plants. The tillering dynamics were also modified by PGPR since Az+ plants had lower tillering rate, mainly secondary tillers, with lower maximum number of tillers and lower death rate, reaching the same number of final tillers, resulting in a higher survival rate. This results in a better use of resources, since, although non-reproductive tillers translocate assimilates to surviving stems, losses in respiration and structural material are high. In addition, although the final number of tillers was equal, their dry weight was higher. Finally, inoculation also accelerated barley phenology. In summary, the change in development, in the redistribution of dry matter within the plants and the increase in leaf area generation observed in plants inoculated with Azospirillum determine an improvement in leaf area of essential relevance for the increase in yield through sustainable agriculture.microbial inoculant, malting barley, development, aerial biomass generation, foliar and tillering dynamics,
Role of RALF peptides in root hair development and response to low temperatures in Arabidopsis thaliana.Lopez Leonel EmanuelMartinez-Pacheco, J. (1); Rodriguez Garcia, D.R. (1).; Urzúa Lehuedé, T. (2); Núñez-Lilo, G. (3); Meneses, C. (4); Estévez, J.M. (1-2).(1) Fundación Instituto Leloir and IIBBA-CONICET. Av. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina. (2) ANID - Millennium Science Initiative Program - Millennium Nucleus for the DeveIopment of Super Adaptable Plants (MN-SAP), Santiago 8370146, Chile. ANID - Millennium Science Initiative Program - Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile. Centro de Biotecnología Vegetal (CBV), Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370146, Chile. (3) Escuela de Agronomía, Facultad de Ciencias Agronómicas y de los Alimentos, Pontificia Universidad Católica de Valparaíso, Quillota 2263782, Chile. (4) Departamento de Fruticultura y Enología, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile. Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, ChileRALFs are a family of peptides involved in various biological processes in plants, such as root growth, cell expansion, pollen tube development, and immunity, among others. In Arabidopsis thaliana, over 30 types of RALF peptides have been identified, several of which play a role in root development. Our initial results demonstrate the involvement of these peptides in root hair development. Firstly, upon exposing plants to synthetic RALF peptides, we observed a stimulation of root hair growth. Additionally, through root RNA-seq analysis, we detected differential expression of several RALF genes following exposure to low temperatures. Finally, we conducted confocal microscopy analysis to examine the expression of a specific RALF in root hairs under low-temperature conditions. These findings contribute to a better understanding of the function of RALF peptides in root hair development in Arabidopsis thaliana and have implications for future research in this field.RALFs peptides, root hair development, low temperatures, Arabidopsis thaliana
Dissecting cadmium-induced metabolic changes in the root tip during early maize growthSusana M. GallegoMatayoshi, C.L. (1,2); Jiménez Guaman, O.M. (1); Esteso, M.L. (1); Pavoni, M. (1); Arán M. (3); Pena, L.B. (1,2); Gallego S.M (1,2)(1) Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica. (2) UBA-CONICET. Instituto de Química y Fisicoquímica Biológicas (IQUIFIB). Argentina. (3) Laboratorio de Resonancia Magnética Nuclear, Fundación Instituto Leloir, IIBBA-CONICET. Argentina.Cadmium (Cd) contamination of arable soils is a great concern worldwide. In cereals, the seminal root is the first organ to come into contact with Cd ions and undergo their toxic effects during the pre-emergence stage. Here, we focus on the metabolic adjustments induced by Cd in the active growth zone of the developing seminal root in maize (Zea mays L) during pre-emergence. An increase in width (38%) and decrease in length (50%) was detected in roots after 72 h exposed to 25 µM CdCl2. In root tips, Cd-induced H2O2 accumulation and lipid peroxidation. These changes were accompanied by increases in lipoxygenase activity and 4-hydroxy-2-nonenal content. Through an NMR spectroscopy analysis, the abundance of 38 water-soluble metabolites was found to be significantly modified by Cd exposure; this set of metabolites comprised carboxylic acids, amino acids, carbohydrates, and unidentified phenolic compounds. The proteomic analysis of root apexes detected 2,191 different proteins; 70 were exclusive of Cd-exposed samples. A statistical analysis allowed us to identify differentially accumulated proteins (DAPs) in the active growth zone of the seminal root tip: 114 increased by 2-fold or more compared to control seedlings, while 80 decreased by 0.5-fold or more. Among metabolic processes, Cd up-regulated oxylipin metabolic pathways in maize root apexes. Root tip metabolism was shifted towards the oxidative pentose-phosphate, glycolytic/pyruvate pathways by Cd. Also, the Met salvage pathway appears as a key metabolic module in maize root tips under Cd stress which may be associated with iron homeostasis and ethylene biosynthesis. Cell wall-related proteins involved in defense, extensibility, and metal binding are important components of maize root tip response to the metal. Overall, the maize root tip shows metabolic flexibility during Cd stress, with key proteins involved in activating a fine-tuning of the cellular metabolic network.abiotic stress, heavy metal, metabolism, plant proteomic, Zea mays L.
Altitude-plant density interaction on Andean maize: contributions to decision makingDiego Antonio SalveMaría Luján Maydup (3), Eduardo Tambussi (3), Germán Salazar (1), Mariana Antonietta (3)(1) UNSa-CONICET, INENCO, Argentina. (2) Instituto de Investigación y Desarrollo Tecnológico para la Agricultura Familiar (IPAF) Región NOA (INTA), Argentina. (3) Universidad Nacional de La Plata-CONICET, Instituto de Fisiología Vegetal (INFIVE), Argentina.In the Northwest of Argentina, yields are limited by a progressive decrease in temperature with increasing altitude, but also by a lack of specific management strategies to underpin traditional practices. Our hypothesis is that increasing plant densities could compensate for the delay in planting date and phenological development at higher altitudes. The landrace “Amarillo de ocho” was grown at two densities (5.71 pl m-2 –conventional for this area- and 8.57 pl m-2) in two field trials conducted during 2021-22 in Hornillos (HOR), Jujuy (23º39’S, 65º25’W, 2300 masl), and El Rosal (ERO), Salta (24º23’S, 65º46’W, 3350 masl) without water or nutrients limitations. Additionally, samplings in 8 farmer’s fields spanning from 2400 to 3400 masl were carried out during 2022-23 growing season where plant density and yield were registered. Average temperature during the crop cycle was 39% lower at ERO compared with HOR, but thermal time requirements from emergency to reproductive stage decreased by 30% at ERO, partially compensating for the phenological delay. Increasing altitude resulted in 50% lower biomass at harvest and 86% lower yields (1107 Kg ha-1 at ERO vs. 7912 Kg ha-1 at HOR). Higher plant densities improved yield at HOR (+29%), related with 37% higher kernel number m-2 together with a slight reduction in kernel weight (-7%) whereas at ERO, a higher yield improvement (+44%) was related with a higher increase in kernel number m-2 and a larger decrease in kernel weight (-20%). Across farmer’s fields, yield per plant negatively related with increasing plant densities (from 6 up to 16 pl m-2), with a trend towards higher improvement in kernel number m-2 and larger decrease in kernel weight in the highest altitude sites (>3000 masl). Thus, increasing plant density could improve yields in high altitude environments especially due to increased kernel number m-2.Andean maize, Plant density, altitude, landrace, Northwest of Argentina.
Glucosinolate translocation from inflorescences to stems during postharvest senescence of broccoliCasajus VictoriaCasajus, V. (1); Martínez, G. (1); Gómez Lobato, M.E (1)(1) Instituto de Fisiología Vegetal CCT CONICET La Plata, UNLP – Diagonal 113 nro. 495, La Plata, Argentina.Broccoli's consumption contributes to the human diet compounds with beneficial effects on health. This vegetable - belonging to the Brassicas family - has a high content of antioxidants, vitamins and glucosinolates. Glucosinolates (GLs) are secondary metabolites whose degradation products have biopesticide activity and have been shown to have a protective effect against various types of cancer. Broccoli is harvested manually and only the flower head is consumed disregarding the other tissues collected during harvest (stems and stalk). Once the harvest is done, the yellowing of the inflorescences begins, which causes both a nutritional and commercial loss of this vegetable. In this work, 15 heads of broccoli were harvested with the same stem length in order to study senescence in the different parts of the harvested organ. The heads were placed in plastic cups and stored at 20 °C for 5 days in the darkness. On day 0 (harvest day) and day 5 (final of harvest) the heads were divided into three sections: inflorescences (section 1: S1), the small stems (section 2: S2) and the main stem (section 3: S3).  The three sections were cut in liquid nitrogen and then stored at -80 °C for posterior analysis. The content of individual glucosinolates was measured with a UPLC unit coupled to a mass spectrometer and the expression of the genes involved in the glucosinolate biosynthesis, degradation and transport pathways was analyzed by qRT-PCR. A sharp decrease in GLs content was detected in inflorescences, but a significant increase was found in the stems.  Expression studies of genes coding for biosynthesis, degradation and transport strongly suggest that GLs are transported from inflorescences to stems rather than a de novo biosynthesis in stems or degradation in inflorescences. Taking into account this results could think use the stems in order to obtain bioactive components in order to improve the nutritional values ​​of different food products.postharvest, brassica, glucosinolate
The effect of dwarfing genes on the rhizosphere bacterial community colonization under limiting phosphorus conditionsFigueroa, P. (1)Gualano, L. (1); Moriconi, J. (1); Sannazzaro, A. (1) ; Santa-María, GE. (1)(1) Instituto Tecnológico Chascomús (INTECH), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional de General San Martín, Argentina.The modification of components of the Gibberellin-Gibberellin Receptor-DELLAs module (GA-GID-DELLAs) was pivotal for the green revolution. Current evidence indicates that it contributes to determine nutrient acquisition, while also influences key symbiotic interactions. The extent to what it globally influences plant soil microbe interactions awaits to be explored. Here we inform the colonization patterns of soil bacterial communities in the rhizosphere of barley (Hordeum vulgare) near isogenic lines affecting some components of the GA-GID-DELLAs module, grown under phosphorus limiting conditions. Plants of WT, M463 (defective in GAs synthesis) and M640 (dwarf, bearing an altered DELLA allele) lines were grown in a low phosphorus (P) soil. The rhizosphere bacterial community was assessed by high throughput 16S rRNA gene sequencing. Alpha and beta diversities were calculated to identify diversity within and between samples respectively. Different abundance tests were performed to find significant taxa associated with the barley lines. 5,114 OTUs sharing 97% similarity were identified. The most abundant taxa at phylum level were Proteobacteria (37.2-54.7%), Actinobacteria (11.5-32.9%) and Acidobacteria (8.0-18.2%). The most abundant genera were Sphingomonas, Massilia and Gaiella. Alpha and beta diversities of the bacterial community were not significantly different among the three barley lines. However, between the three genotypes, abundances of 2 phyla, 1 class, 2 orders, 3 families and 3 genera were found significantly different (P<0.05) according to Kruskal test. The genera Massilia, Devosia, Phaselicystis and Dongia were identified as main biomarkers in M463. On the other hand, Gemmatimonas, Rhizomicrobium, Phenylobacterium and Exiguobacterium were biomarkers in M640, and Arthrobacter, Duganella, Variovorax and Azonexus were biomarkers in WT. Our study provides the first clues on the role of barley dwarfing genes on the rhizosphere bacterial community assembly.Dwarfing genes, rhizosphere, 16S rRNA, bacterial community, microbiome, phosphorus limitation.
Importance of Calcium ATPases in root hair development in Arabidopsis thaliana.Carignani Sardoy, Mariana (1)Candeo, A. (2); Tortora, G. (2); Bassi, A. (2); Buratti, S. (3); Costa, A. (3); Garcia Bossi, J. (4); Muschietti, J.P. (4); Borassi, C. (5); Estevez, J.M. (1,6)(1) Fundación Instituto Leloir and IIBBA-CONICET, Buenos Aires, Argentina. (2) Dipartimento di Fisica, Politecnico di Milano, Milano, Italia. (3) Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italia. (4) Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor Torres (INGEBI-CONICET), Buenos Aires, Argentina. (5) Wageningen University & Research, Laboratory of Biochemistry, Wageningen, The Netherlands. (6) Centro de Biotecnología Vegetal (CBV), Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile.Root hairs are specialized root epidermal cells important for water and nutrient uptake as well as necessary for attaching plants to the soil. These cells present polarized growth, meaning they go through an elongation process in only one direction. This type of growth is characterized by an oscillatory behavior based on cytosolic Ca2+ and extracellular ROS gradients as well as a decrease in cytosolic pH towards the tip of the root hair. In this project we aim to study the cytosolic Ca2+ oscillations associated with polarized growth. Our research focuses on Ca2+ ATPases, and their importance in keeping the Ca2+ homeostasis in root hairs. To do this, we made an analysis of RNA sec microarrays of Arabidopsis thaliana to determine the expression pattern of these proteins in root and root hairs. Based on these results, we chose four different Ca2+ ATPases and performed an analysis of root hair length in insertional mutants for these four ATPases (SALK and SAIL lines). So far, we have identified a very strong phenotype in one of these mutants. In addition, we treated these lines with Eosin Y (a known inhibitor of Ca2+ ATPases) and analyzed the resulting root hair length. Our following steps center around the study of this protein’s structure and function as well as an in vivo analysis of cytosolic Ca2+ dynamics in the root hair tips by using the Ca2+ biosensor YC3.6.Arabidopsis thaliana, root hairs, molecular biology, calcium oscillations
Temperature during seed maturation influences weedy rice seed dormancy and germinationGabriela AugeAuge, G.A. (1, 2, 3, 4); Takama, R. (4); Imaizumi, T. (4)(1) Consejo Nacional de Investigaciones Técnicas y Científicas (CONICET), Argentina. (2) Instituto de Agrobiotecnología y Biología Molecular (IABIMO), INTA-CONICET, Argentina. (3) JSPS International Invitational Fellow, Japan. (4) Institute for Plant Protection, National Agriculture and Food Research Organization (NARO), Japan.The maternal environment during seed development and maturation significantly influences many properties of progeny seeds. In Japanese weedy rice, warmer temperatures following flowering impede progeny seeds to release dormancy, likely increasing their persistence in the soil seed bank. However, the timing of establishment of such effects remains unresolved. In our study, we examined how warm temperatures during early and late seed maturation stages affect progeny germination, while also exploring transcriptomic changes in seeds before dispersal from mother plants and their association with progeny responses. Our findings show that late post-flowering warming (3-6 weeks) reduced progeny germination compared to control plants without temperature treatment, similarly to higher temperatures during the entire reproductive period. Conversely, progeny seeds from plants exposed to early warming (0-3 weeks after flowering) exhibited high germination similar to those of control plants. Field validation involved two cohorts of plants transplanted 1.5 months apart: mid-May transplants experienced higher late seed maturation temperatures and produced more dormant seeds than late-June transplants. At 6 weeks after flowering, warm temperatures throughout the reproductive period resulted in changed expression of a substantial number of genes (1059 up- and 864 down-regulated). In turn, early (up: 54, down: 50) or late (up: 58, down: 50) warming exposures had a significant effect on a smaller set of genes compared to control plants. Gene-ontology analysis revealed ‘metabolic pathway’ category enrichment across all gene groups, indicating that warm temperatures profoundly influence seed metabolism and subsequently impact progeny seed germination. These findings provide valuable insights into the responses and mechanisms associated with maternal effects, which can potentially modify weed emergence in the field, particularly in the context of climate change.

Warming effects on growth and photosynthetic gas-exchange during the autumn and winter in young olive trees (Olea europaea L.)Virginia María Cortés MolinaMiserere, A. (3); Argañaráz, R. A (1); Castro, D. N. (1); Rousseaux, M. C. (1,2); Searles, P. S, (1)1 Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-Provincia de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET), Entre Ríos y Mendoza s/n, Anillaco 5301, La Rioja, Argentina 2 Departamento de Ciencias Exactas, físicas y Naturales (DACEF y N), Universidad Nacional de La Rioja, Av. Luis M. De la Fuente s/n, Ciudad Universitaria de la Ciencia y de la Técnica, La Rioja 5300, La Rioja, Argentina 3 Centro de Investigación e Innovación Tecnológica (CENIIT), CONICET, Universidad Nacional de la Rioja (UNLaR); Gdor. Luis Vernet y Apóstol Felipe (5300), La Rioja, ArgentinaDifferences in air temperature are common between olive production areas in northwest Argentina due to altitude and other topographical features. Additionally, the average annual air temperature is rising due to global warming. Nevertheless, few studies have examined how autumn and winter temperatures may affect plant growth. The objective of this research was to determine the shoot growth rate and the emergence of new leaf pairs during and after either an autumn or a winter warming period. Photosynthetic gas-exchange at midday was also assessed on some dates. To conduct the experiment, young, potted olive plants of two cultivars (cvs. Arbequina, Picual) were placed in open-top chambers at either near ambient temperature or heated by four degrees Celsius for 60 days (autumn or winter). During the autumn period, the absolute shoot elongation rate and new leaf emergence were much greater in warmed plants than in the near ambient temperature controls for both cultivars. In contrast, no vegetative growth occurred during the winter period under either temperature regime. Stomatal conductance and net leaf photosynthesis at midday were generally not different between temperature regimes, although transpiration was often greater in the warmed treatment for both cultivars due to a greater atmospheric vapor pressure deficit at higher temperatures. Little difference in net photosynthesis likely reflects the fairly optimal temperatures for photosynthesis at midday under both treatments (20 – 30 degrees Celsius). When vegetative growth started again towards the end of winter, the shoot growth rate of warmed plants appeared to be less than that of the controls for both cultivars and warming periods. Taken as a whole, these results suggest that vegetative growth in the autumn will increase with global warming, although the consequences of this growth for olive production are currently unknown.

Olea europaea, global warming, vegetative growth, photosynthesis
Forests facing drought and heat-waves: the need of a physiological-based forestry to increase plantations adaptability to climate changeFernández, María Elena (1)Monteoliva, S. (2); Barotto, J. (2); Bulfe, N (3); Giana, F. (4); Sergent, A.-S. (4); Gándara, J.M. (5); Gatica, G. (1); Martínez-Meier, A. (4); Gyenge, J. (1)(1) Lab. Internacional Asociado Forestia, UEDD INTA-CONICET IPADS, Sede Tandil, Argentina; (2) Facultad de Ciencias Agrarias y Forestales, UNLP, La Plata, Argentina; (3) Estación Experimental Agropecuaria Montecarlo, INTA, Argentina; (4) Lab. Internacional Asociado Forestia, INTA EEA Bariloche - UEDD INTA-CONICET (IFAB INTA-CONICET), Bariloche, Argentina; (5) Fac. de Agronomía, Univ. de la República, Montevideo, UruguayIncreased tree mortality is a phenomenon widely reported over the last decades in different species and forests around the world. About 70% of the global drought-induced tree die-offs have been related to the combined effects of drought and heat waves (i.e. “hotter-drought” events) mainly associated with global warming. The hydraulic disfunction of the trees has been proposed as the main physiological driver of tree death. In forest plantations intensively managed to feed different industries this kind of event is rarely reported. However, they are not immune to extreme climate events, as was shown in a recent mortality event occurred in Corrientes province, Argentina, due to the combination of prolonged extreme drought and heat waves. In this sense, even when mortality events might not be observed, decreased productivity due to abiotic stress (alone or in combination with biotic agents), may represent a serious threat for their sustainability. New paradigms are needed to face climate change impacts posed on planted forests since most of the strategies applied until now has been oriented to increase productivity (and sometimes, also for wood quality). However, due to functional relationships and constraints, these objectives are sometimes compromised with abiotic stress resistance. In this talk, three major strategies are discussed and exemplified with study cases of Pinus spp and Eucalyptus spp, aiming to show possibilities and current limitations to develop a climate-smart forestry: a) species and genotype selection as well as genetic improvement oriented to abiotic stress resistance (and the potential trade-offs with growth and wood quality traits); b) planting site selection at landscape level to decrease mortality risks; and c) silvicultural management to reduce climate sensitivity and increase resistance and/or resilience to extreme climatic events.drought resistance, planted forests, tree mortality, climate-smart forestry
The role of mitochondrial H2S in stomatal immunityRosario PantalenoScuffi, D. (1); Costa, A. (2); García-Mata, C. (1)(1) Mecanismos de Señalización en Plantas, Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, 7600 Mar del Plata, Argentina. (2) University of Milan, Department of Biosciences, Milan, 20133, Italy.Land plants have little holes in their epidermis, known as stomata, responsible for the gas exchange between plants and their environment. Stomata are formed by pairs of specialized cells, the guard cells, delimitating a central pore. Guard cells sense different stimuli and integrate them into a complex signalling network that regulates the pore size. When compared with their neighboring cells, guard cells have unique characteristics, like a higher mitochondrial density and respiration rate. Nevertheless, the role of mitochondrial activity on stomatal closure is not fully understood.

Some pathogens use natural apertures like stomatal pores to invade plants. Hence, plants evolved to recognize conserved motifs in pathogens, the pathogen-associated molecular patterns (PAMPs). The perception of PAMPs triggers multiple defense responses, including ROS production, gene reprogramming and stomatal closure, as a first mechanical barrier to reduce infection.

The gasotransmitter hydrogen sulfide (H₂S), is a very reactive molecule that regulates different physiological processes, including stomatal closure. Despite that Arabidopsis has enzymatic H2S sources in different subcellular compartments, most works on the biological effect of H2S in plants have focused on the main cytosolic source DES1.

In this work, we studied the role of the mitochondrial H2S source β-CYANOALANINE SYNTAHASE (CAS-C1) on stomatal immunity. Previous results obtained in our lab show that flg22-triggered stomatal closure, apoplastic and cytosolic ROS increase, were impaired in cas-c1. In this work, we present evidence indicating that cas-c1 shows a differential expression of   flg22-induced  genes . Moreover, using radiometric sensors we show that flg22 increases the mitochondrial activity in guard cells, response that is disrupted in cas-c1. Taken together, results suggest that CAS-C1 is needed for flg22-induced stomatal immunity, response that involves mitochondrial activity.
stomata, hydrogen sulfide, mitochondria, pathogens
First functional study of a subfamily III member of the Snakin/GASA family in Solanum tuberosumVazquez-Rovere, C. (1)Nahirñak, V. (1); Almasia, N.I. (1)(1) Instituto de Agrobiotecnología y Biología Molecular, UEDD-INTA-CONICET, CICVyA, INTA-Castelar, Argentina.Snakin/GASA peptides are cysteine-rich AMPs whose functions are not fully understood. Their participation in various aspects of development and biotic or abiotic stress tolerance has been described.

In potato we have identified 18 genes of the Snakin/GASA family, being Snakin-1, Snakin-2 and Snakin-3 members of subfamilies I, II and III, respectively. So far, SN1 and SN2 have been functionally characterized by demonstrating their antimicrobial activity against fungi and bacteria.

In order to study the role of a member of the 3rd subfamily in plant development and responses to various stresses, we obtained transgenic potato lines with altered levels of Snakin-3, we conducted in-silico and in-vivo studies of its promoter and we determined its subcellular localization. The results obtained so far suggest a functional differentiation of Snakin-3 since it has a differential expression regulation with respect to Snakin-1 and Snakin-2 and presents a different subcellular location, being found in the endoplasmic reticulum. Likewise, in this work we will present the advances made in the molecular and morphological characterization of transgenic lines and in challenge tests against bacterial pathogens.
SNAKIN/GASA, potato, snakin-3, antimicrobial, cystein-rich
From comparative transcriptomics in apomictic species to the induction of apospory-like phenotypes in ArabidopsisSilvina Claudia PessinoColono, C.M., Siena, L.A., Podio M., Stein J., Delgado, L., Ortiz J.P.A.Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR-CONICET-UNR), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de RosarioThe combined use of sexuality and apomixis in plant breeding programs have a positive impact on the time and cost required to produce improved cultivars. This methodology has potential for crop diversification and decreasing of seed costs. Currently, this strategy is being used only in natural apomictic species like those included in the Paspalum, Brachiaria and Panicum genera, but molecular research in the field is evolving quickly, making its transference to the breeding of sexual major crops a conceivable possibility. In last two decades, we used RNAseq to extensively characterize gene differential expression in ovules of sexual and aposporous apomictic Paspalum notatum plants and identified numerous guilty-by-association genes, some of which map in the genomic region responsible for apomixis in the species. Reverse genetics analyses using GFP-fusion expression lines, DIC and confocal cytoembryology, crosses with cell-identity fluorescent marker lines, in situ chromosome counting and flow cytometry in both wild type and mutant/transformant contexts are revealing that the orthologs of some of these candidates can induce apospory-like phenotypes (i.e., the formation of multiple non-reduced functional megaspores and supernumerary mature gametophytes with altered polarity and unusual cell identity) in the sexual model species Arabidopsis thaliana. This work establishes a proof of concept that candidate genes identified in the Paspalum system can be used to develop molecular tools, in order to induce reproductive mode changes within breeding programs.apomixis, apospory, plant development, plant reproduction
The ecophysiology of seedling recruitment during floods: The case of Echinochloa colona, a harmful arable weed of extensive cropsMollard, FedericoEcheverry Holguín, J. (1,3); Crepy, M. (2); Striker, G.G. (1,3)1 Facultad de Agronomía-Universidad de Buenos Aires, Av. San Martín 4453, CABA, Argentina. 2 INTA Concepción del Uruguay-CONICET. 3IFEVA (FAUBA-CONICET), Av. San Martín 4453, CABA, ArgentinaIn the Pampas, the transition of floodplains to agriculture has facilitated the encroachment of hydrophyte weeds. Our objectives were: (i) to investigate whether flooding controls or promotes Echinochloa colona spread and, (ii) to explore environmental cues that can stimulate underwater germination of its seeds. To address (i), we conducted two flooding experiments (flood level: 10-15 cm) in soil mesocosms obtained from floodplain crops in the Province of Buenos Aires (corn/wheat-soybean/sunflower rotation) and taken to FAUBA experimental field. We simulated the seasonal decrease in floodwater levels throughout the growing season by draining mesocosms monthly starting from winter (year 1). In year 2, we simulated intermittent flood and drainage conditions of varying monthly durations. Experiments included mesocosms constantly flooded and drained to field capacity (controls). We weekly monitored seedlings emergence and recorded established plants, as well as their biomass and fecundity. Significant interactions between treatment and time were observed for emergence in both years (p<0.05). The peaks of emergence coincided with drainage periods, indicating that floods shifted emergence timing towards the summer. Underwater emergence (<100 seedlings m-2) occurred, producing few yet prolific plants even in constant flooding. The results from both years demonstrate that floods delayed E. colona emergence causing it to occur later in the growing season. For objective (ii) we did lab experiments following these hypotheses: 1) High-amplitude daily alternating temperatures (AT) promote underwater germination, 2) Osmopriming under drained conditions promote later underwater germination. Results indicate that both high-amplitude AT and KNO3 osmopriming were promoted E. colona underwater germination in hypoxia. This research highlights the influence of environmental factors on subaquatic germination in E. colona, which could have implications for its population dynamics.seedling emergence, establishment, flooding, recruitment, seed germination, submersion, Junglerice
Shedding light onto the role of the Plastid terminal oxidase (PTOX) as a safety valve for photoprotection in plantsPablo Ignacio CalzadillaSong J. (1), Gallois P. (2) and Johnson G.N. (1)(1) Department of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, United Kingdom. (2) Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.The Plastid Terminal Oxidase (PTOX) is a chloroplast localized plastoquinone oxygen oxidoreductase which has been suggested to have the potential to act as a photoprotective safety valve for photosynthesis. However, PTOX overexpression in plants has been unsuccessful at inducing photoprotection, and significant PTOX activity has only been observed in a small number of stress-tolerant species. Thus, until now, the role of PTOX in photoprotection has been questioned, and the factors that control its activity remain elusive. Here, we show that significant PTOX activity is induced in response to high light in the model extremophile plant Eutrema salsugineum. This activation correlates with structural reorganization of the thylakoid membrane. Over-expression of PTOX in mutants of Arabidopsis thaliana perturbed in thylakoid stacking also results in such activity, in contrast to wild type plants with normal granal structure. We conclude that structural re-arrangements of the thylakoid membranes, bringing Photosystem II and PTOX into proximity, are both required and sufficient for PTOX activation. Further, we show that overexpression of PTOX in Arabidopsis stacking mutants protects against photoinhibition of Photosystem II and reduces reactive oxygen production under stress conditions.
Our findings thus demonstrate a role for PTOX in photoprotection and set the basis for new strategies to redesign photosynthesis using PTOX, aiming to the generation of higher stress tolerance plants.
EFFECT OF WATER STRESS ON THE ENDOGENOUS CONTENT OF BRASSINOSTEROIDS IN SUNFLOWER PLANTS DURING LATE VEGETATIVE GROWTH (V8)Ramirez, Federico (1)Boero, A. (1, 2); Oklestkova, J. (3); Strnad, M. (3); Vigliocco, A. (1,2); Andrade, A. (1, 2); Alemano, S. (1, 2)(1) Laboratorio de Fisiología Vegetal, Fac. de Cs. Ex.-Fco.-Qcas y Nat., Universidad Nacional de Río Cuarto (UNRC), Río Cuarto, Córdoba, Argentina. (2) Instituto de Investigaciones Agrobiotecnológicas (INIAB); CONICET-UNRC, Río Cuarto, Córdoba, Argentina. (3) Laboratorio de Reguladores de Crecimiento, Instituto de Botánica Experimental, Academia Checa de Ciencias y Universidad Palacký, Olomouc, República Checa.Water stress is considered one of the most damaging abiotic stresses that negatively affect the growth, physiology and metabolic functions of plants. A common physiological modification under water stress is the alteration in the endogenous concentration of phytohormones, including brassinosteroids. Our aim was to evaluate the impact of water stress on the endogenous levels of brassinosteroids (BRs) in the aerial part and roots of sunflower plants. For this, six inbred lines -previously characterized as tolerant to water stress (B71), sensitive to water stress (B59), intermediate tolerant to water stress (C803, B481-6 and R461-4) and intermediate sensitive to water stress. (R453)- were subjected to moderate water stress caused by irrigation suppression for 15 days under controlled environmental conditions, during their late vegetative growth (V8). The plants were harvested, sectioned into aerial part and roots and endogenous hormonal determinations were performed. The extraction and purification of the BRs was carried out from 5 mg of dry weight of plant tissue, using acetonitrile and immunoaffinity columns; identification and quantification was performed by UHPLC-MS/MS. Regarding the quantified BRs, the B481-6 line showed the greatest changes: in the aerial part the levels of 24 epibrassinolide (EBL), castasterone (CS), 28-homocastasterone (28 HCTS), 28-norcastasterone (28-NCTS) and brassinolide (BL) increased, while in roots increased 28-HCTS, 28-NCTS and CS. The sensitive line showed increases in EPL, 28-HCTS, BL and CS in aerial part and decreases in EPL, 28-HCTS and 28-NCTS in roots. In the tolerant line, EPL, 28-NCTS and CS increased and BL decreased in aerial part. In roots, only a decrease of 28 HCTS was observed. The detection of BRs from different C28 (CS, BL and EBL) and C29 (28-HCTS and 28-NCTS) synthesis pathways suggests the existence of independent pathways for BRs biosynthesis in sunflower plants under our experimental conditions.sunflower, water stress, phytohormones, brassinoesteroids, late vegetative growth
APPLICATION OF PLANT GROWTH REGULATORS IN SUNFLOWER SEEDLINGS UNDER WATER STRESS CONDITIONS DURING EARLY VEGETATIVE GROWTH (V4)Boero, Aldana (1,2)Ramírez, F. (1); Vigliocco, A. (1,2); Andrade, A. (1,2); Alemano, S. (1,2)(1) Laboratorio de Fisiología Vegetal, Fac. de Cs. Ex.-Fco.-Qcas y Nat., Universidad Nacional de Río Cuarto (UNRC), Rio Cuarto, Córdoba, Argentina. (2) Instituto de Investigaciones Agrobiotecnológicas (INIAB), CONICET-UNRC, Rio Cuarto, Córdoba, Argentina.It is widely documented that in sunflower water stress modifies various processes involved in plant growth and development. Plant growth regulators are compounds that play crucial roles during the life cycle of plants and are also involved in responses to abiotic stress. Our aim was to evaluate the action of different plant growth regulators on the growth of sunflower seedlings subjected to water stress. For this, seedlings of two inbred lines (B59 and B71, sensitive and tolerant to water stress respectively) were grown in pots with sterile substrate inside Conviron PR48 Environmental rooms. From the 3rd day after sowing, and every 2 days, saturation irrigations were performed using Hoagland's solution 50% ionic strength; and 10 days after sowing, the water stress treatment was started using 265 mM mannitol solution. After 17 days, and every 2 days, the plant growth regulators were applied by foliar spray with GR24 (3 µM), BL (0.01 µM) and KAR2 (10 nM) solutions. At 24 days (growth stage V4) the seedlings were harvested, sectioned into aerial and root parts and the determinations were made. In general, the effect of the application of the regulators was observed in seedlings of both lines, both in control and water stress conditions. The application of GR24, BL and KAR2 in stressed seedlings mainly resulted in a greater length of taproot, dry weight of aerial part and dry weight of roots. GR24 and BL increased the leaf area and fresh weight of the aerial part, while KAR2 increased the fresh weight of the roots. Similarly, in control seedlings, GR24 and BL stimulated leaf growth and, together with KAR2, taproot elongation. It is important to highlight that the application of plant growth regulators resulted in an improved relative root biomass in response to water stress for both lines.water stress, plant growth regulators, sunflower, roots, early growth.
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