Abiotic Stress Responses in Legumes: Strategies Used to Cope with Environmental Challenges

Legumes are well recognized for their nutritional and health benefits as well as for their impact in the sustainability of agricultural systems. The threatening scenario imposed by climate change highlights the need for concerted research approaches in order to develop crops that are able to cope with environmental stresses, while increasing yield and quality. During the last decade, some physiological components and molecular players underlying abiotic stress responses of a broad range of legume species have been elucidated. Plant physiology approaches provided general outlines of plant responses, identifying stress tolerance-related traits or elite cultivars. A thorough identification of candidate genes and quantitative trait loci (QTLs) associated with these traits followed. Model legumes like Medicago truncatula, Lotus japonicus, and more recently, Glycine max provided valuable translational approaches for dissecting legume responses to abiotic stresses. The challenge now focuses on the translation of the information gained in model systems in controlled environments to crops grown under field conditions. In this review, we provide a general overview of the recent achievements on the study of abiotic stress responses in a broad range of model, grain and forage legumes species, highlighting the different approaches used. Major accomplishments, as well as limitations or drawbacks are discussed across the different sections. Some perspectives regarding new approaches for screening, breeding or engineering legumes with desirable abiotic stress resistance traits are anticipated. These advances will support the development of legumes better adapted to environmental constraints, tackling current demands on modern agriculture and food production presently exacerbated by global climate changes

Regeneration and characterization of plants produced from mature tobacco pollen protoplasts via gametosomatic hybridization

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Development of a freezing test in controlled conditions for Pisum sativum

BAPGEAPSIFreezing is a major environmental limitation to crop productivity for a number of species including legumes. In the context of global climate change, winter crops will experiment milder autumn temperatures that could be detrimental to the achievement of cold acclimation, which is the ability for plants to increase their level of frost tolerance (FT) in response to low but non-freezing temperatures. For the pea crop, a modelling approach has shown that climate warming will increase the occurrence of freezing damage events, even if these latter will be less severe (Castel et al., 2014). Thus, breeding for frost tolerant winter peas requires not only to improve their FT threshold, but also to raise their cold acclimation rate. In order to evaluate the genetic variability of both traits, we are adjusting a protocol in controlled conditions, which provides an indirect evaluation of FT by the measurement of tissues’electrolyte leakage (EL). Pea stem samples have been collected after variable durations of cold acclimation at 4°C day/2°C night in a climatic chamber. They have been then progressively cooled at 2°C h-1 in a programmable temperature-test chamber to reach test temperatures ranging from +4°C to -36°C. After 14 days of cold acclimation, EL evaluation enabled the same ranking of genotypes according to their FT threshold as obtained in the Chaux-des-Prés field platform. Improvements of the protocol are however still needed to use it as a routine ranking test

Identification of genes underlying frost tolerance within a pea QTL

National audienceSeeding legumes in autumn would allow increasing and regulating yield, but requires to improve the level of frost tolerance in varieties, which motivates the interest in deciphering the genetic determinism of this trait. In pea (Pisum sativum L.), this character is controlled by a few quantitative trait loci (QTL) that were identified by the analysis of RIL populations derived from contrasted genotypes, such as Champagne (Ch, tolerant) x Térèse (Té, sensitive), or by association analysis [1,2,3]. We study a QTL located on the pea linkage group 6 (WFD6.1), which accounts for a large part of frost tolerance variability, making it a choice target for selection purposes. In order to get access to the QTL structure in Ch and Té, we exploited pea and Medicago truncatula (Mt) genomic resources [4,5]. Thus, we keyed out within WFD6.1 genes encoding CBF-like transcription factors (TFs) present in a Mt orthologous QTL and known to be involved in frost tolerance in various plant species. We built BAC libraries for Ch and Té, screened them with probes designed in CBF genes across WFD6.1, then sequenced and assembled positive clones. The region turns out to be 33 % larger in Té than in Ch. Besides, a gene annotation, performed using the PlantTFcat database, shows that TFs are distributed across three loci in Ch and two in Té, only one of them being common. We are currently refining this analysis, aiming at extensively describing polymorphism across WFD6.1, especially in CBF genes, in order to set up a catalogue of their diversity. We present here preliminary results from this approach

Transcriptome analysis in pea allows to distinguish chilling and acclimation mechanisms

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceIn order to distinguish chilling and freezing tolerance mechanisms in pea, responses to cold exposure were compared between the freezing tolerant line Champagne and the sensitive line Terese. Global gene expression was considered in the two lines and associated with morphological, histological and biochemical approaches. The chilling tolerance in both lines was related to responses of the CBF, COR and LEA genes belonging to the CBF regulon, with greater earliness of expression in the Champagne genotype. The freezing tolerance, only observed in Champagne, was associated with acclimation processes such as cellular osmotic stabilization, photosynthesis modifications, antioxidants production, modifications in hormone metabolism, cell wall composition and dynamics. (C) 2012 Elsevier Masson SAS. All rights reserved