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In the context of climate change, characterized by increasingly frequent droughts and heat waves, it is anticipated that the global soybean yields, the most extensively grown legume, will experience a significant decline in the foreseeable future.. There is thus an urgent need to improve its ability to maintain growth and productivity under such conditions. The objective of this study was to explore which plant traits make soybeans more resilient to heat and/or water stress, with a focus on plant architecture. For this purpose, two soybean genotypes, already shown to have contrasted root architecture (Maslard et al., 2021) were grown under controlledconditions in the high-throughput phenotyping platform 4PMI where either optimal conditions, heat waves, water stress or both heat waves and water stresses were applied during the vegetative stage. New root detection algorithms and tools were generated to quickly and accurately analyze many architectural traits (e.g. length, width, projected root area, plant height over time).Under stress conditions the two genotypes displayed contrasted architectural features such as root width, root angle branching or plant height. By correlating architectural to functional traits, related to water and carbon allocation, we were able to explain the stress susceptibility level of the two genotypes. This cross analysis of plant ecophysiology and architectural traits under different stresses provides new information on soybean adaptation to climate change.

Que mangerons-nous, que mangeront nos enfants demain ? Le contenu de nos assiettes ne cesse d'évoluer. Pour beaucoup, la viande n'est plus consommée tous les jours, ce n'est plus l'aliment central du repas. Qu'impliquent ces changements de menu ? Sont-ils motivés par le souci de mieux manger, d'être en meilleure santé ou imposés par des budgets de plus en plus serrés ? Enquêtes de région va cuisiner l'avenir.

In a context of climate change, with more frequent drought events and heatwaves, it is predicted that soybean yields will drastically decrease in the near future. Soybean being the most widely grown legume crop in the world, there is an urgent need to improve its ability to sustain its growth under such conditions in order to guarantee high levels of productivity. The aim of this study was to explore the influence of heat and/or water stress on soybean growth and its water and mineral nutritions. Two soybean genotypes, displaying contrasted root architectures during their vegetative stage were grown under controlled conditions in the 4PMI high-throughput phenotyping platform where either optimal conditions, or heatwaves, or water stress, or both heatwaves and water stress were applied. Plants were characterized for their morphology, their water uptake and the mineral composition of their tissues. An ecophysiological structure-function framework, enabled us to link structural variables (leaf area, root architecture, biomass, etc.) to functional variables (water use efficiency, element uptake efficiencies…) in order to understand the interactions between water and element flows, and to quantify plant overall tolerance to each stress. Under combined stress conditions one genotype appeared to be more susceptible than the other genotype. No significant change in structural variable was observed in response to the double stress between the two genotypes. However, it appeared that the genotypic difference was more related to functional changes, especially with regard to water absorption. A complementary analysis of the plant ionome under the different stresses, highlighted plant strategies promoting soybean growth under these two stresses, and offered new perspectives for crop adaptation to climate change.

In a context of climate change, with more frequent drought events and heatwaves, it ispredicted that soybean yields will drastically decrease in the near future. Soybean being themost widely grown legume crop in the world, there is an urgent need to improve its ability tosustain its growth under such conditions in order to guarantee high levels of productivity. Theaim of this study was to explore the influence of heat and/or water stress on soybean growthand its water and mineral nutritions. Two soybean genotypes, displaying contrasted rootarchitectures during their vegetative stage were grown under controlled conditions in the4PMI high-throughput phenotyping platform where either optimal conditions, or heatwaves,or water stress, or both heatwaves and water stress were applied. Plants were characterized fortheir morphology, their water uptake, the mineral composition of their tissues and the roottranscriptome. An ecophysiological structure-function framework, enabled us to linkstructural variables (leaf area, root architecture, biomass, etc.) to functional variables (wateruse efficiency, element uptake efficiencies…) in order to understand the interactions betweenwater and element fluxes, and to quantify the overall tolerance of plants to each stress. Undercombined stress conditions, one genotype appeared more sensitive than the other. Nosignificant changes in structural variables were observed in response to the dual stressbetween the two genotypes. However, the genotypic difference was found to be more relatedto functional changes, particularly for water uptake. A complementary analysis of the plantionome and transcriptome under different stresses revealed plant strategies favoring soybeangrowth under these two stresses, and offered new perspectives for crop adaptation to climatechange.

Water stress is recognized as the most severe abiotic stress for agricultural productivity. Root traits play a key role in tolerance to water stress but have largely been neglected in selection schemes. In order to identify the maize genetic bases of the root adaptive responses to water deficit (WD), we used a MAGIC mapping population of 400 lines based on the intercrossing of 16 genotypes. The fine phenotyping of the different genotypes was performed under contrasting water supply on the French root phenotyping platform (4PMI). On the 16 founder genotypes, in addition of phenotyping, we sampled different root tissues daily over 7 days after irrigation arrest and performed RNAseq. On the basis of these 448 transcriptomes, we identified 6945 differentially expressed genes between axial and lateral roots and in response to WD and inferred a regulatory gene network to identify transcription factors (TF). Using a hierarchical clustering, we split the network in 35 clusters homogeneous in their expression pattern. Fine analysis of individual cluster pointed out, without prior knowledge, already known FTs responding to WD and identified new candidates. Functional validation of Arabidopisis orthologues has been initiated and many genotypes have an altered root developmental response to in vitro osmotic stress. In parallel, the phenotyping and a transcriptomic analysis by RNAseq of the genotypes of the mapping population under optimal conditions and water deficit enabled a GWAS and an eQTL analysis. Both approaches identified polymorphisms in genes of interest and identified SNPs colocating near transcription factors also identified by the gene network approach. Taken together all the data identified candidate genes and alleles potentially controlling adaptive root development that can be interesting target for breeding. This work was supported by the European Research Council (ERC) (HyArchi to CM; grant agreement No 788553)

International audience

National audience; In the current context of climate change, periods of water deficit occur more frequentlyalong the crop cycle, leading to high yield losses. To limit the negative impact of recurrentwater deficits, plants can adapt, via the mobilization of “stress memory”, allowing them torespond to a subsequent stress in a faster and/or more intensive manner. After a first stressevent, plants can keep an imprint of this stress via the induction of epigenetic (e.g. memorygene regulation), physiological (e.g. stomatal closure) and molecular (e.g. compoundaccumulation) changes. When maintained between two stress periods, these changes mayprepare plants for a subsequent water deficit.This work addresses the potential role of stress memory in plant adaptation to recurrent waterdeficits with a special focus on plant hydro-mineral uptake by roots. For this purpose, anexperiment was conducted on the high throughput phenotyping platform (4PMI, Dijon, France),where several frequencies of water deficits were applied to pea plants. An integrativeapproach, including a structure-function ecophysiological framework characterizing planthydromineral nutrition (nutrients and beneficial elements), enriched with root and noduletranscriptomic analyses (RNA-seq), revealed the mechanisms underlying the “memory effect”throughout the plant cycle. We will discuss the role of memory genes during recurrent stressesand plant strategies to acquire water as well as macro- and micro-nutrients more efficientlyduring recurrent stresses. This work offers the new perspective of considering plant memoryin the design of ideotypes better adapted to multiple stress events in a context of climatechange.Study conducted in the framework of the EAUPTIC project, supported by the “Fond UniqueInterministériel" (n° 3870401/1), BPIFrance (n° DOS0097244/00), the Regional Council ofBurgundy (n° DOS0133465/00), Dijon Metropole (n° CONV-DM2018-118-20180820), and theFonds Européen de Développement Régional (n° 2018-6200FEO003S01889).

International audience

International audience; Dans le contexte actuel du changement climatique où les épisodes de déficits hydriques deviennent de plus fréquents et surviennent àdifférents stades au cours du cycle, les légumineuses à graines telles que le pois voient leur rendement fortement impacté. Afin de limiter lesimpacts négatifs de stress répétés, les plantes peuvent mettre en place une « mémoire » du stress, qui induit une modification de leur réponseà des stress ultérieurs. Cette mémoire dépend de plusieurs paramètres qui vont moduler l’ampleur et la rapidité de la réponse à un secondstress. Le premier stress peut induire des modifications épigénétiques, physiologiques (e.g. fermeture des stomates) et moléculaires (e.g.accumulation de certains composés avec différentes activités) permettant à la plante de se préparer à un stress futur, la plante gardant une «empreinte du stress passé ». Ces modifications peuvent aussi se poursuivre à la fin du stress en l’attente d’un suivant. Cette préparation de laplante aux stress répétés peut ainsi reposer sur la régulation de l’expression de gènes mémoire. Dans ce contexte, nous faisons l’hypothèseque la valorisation de cet effet mémoire pourrait être une nouvelle cible d’amélioration des variétés de pois, confrontées à des déficitshydriques multiples impactant leur nutrition minérale.Pour tester cette hypothèse, une expérimentation en conditions contrôlées a été mise en place sur la plateforme 4PMI de phénotypage haut-débit de Dijon. Au cours de cette expérimentation, en prenant pour modèle d’étude le génotype Kayanne, quatre modalités de stress hydriquesont été appliquées : un stress hydrique avant floraison (WS1), un stress hydrique après floraison (WS2), une combinaison de deux stresshydriques répétés (WS1+WS2) espacés d’une période de réarrosage, et un stress hydrique continu (WSc). Des analyses écophysiologiquesont été intégrées dans un cadre d’analyse de type structure/fonction et complétées par des analyses moléculaires afin de mettre en évidencel’effet mémoire mis en jeu lors d’un stress répété sur la croissance, le développement et la nutrition hydrominérale de la plante (incluant macro-et micro-nutriments). Afin de mettre en avant les principaux gènes impliqués dans l’effet mémoire de la réponse à un stress hydrique répété,des analyses transcriptomiques ont été réalisées par RNAseq. Nous discuterons de leur rôle dans les grandes voies métaboliques impliquéeset tenterons de les corréler aux variables écophysiologiques étudiées par des approches de modélisation de réseau de gènes. Les processuspermettant d’améliorer la réponse à un stress hydrique répété par la valorisation de la mémoire des plantes ainsi que des gènes candidatssous-jacents seront l’occasion de porter un nouveau regard pour l’amélioration du pois sous conditions hydriques fluctuantes.

International audience; Agriculture is facing the challenges to improve performance and crop adaptation to climate change towards reducing negative impacts of associated abiotic stresses on crop yield and contributing to its mitigation. Climate change comprises more frequent and ample abiotic stresses that plants have to cope with, such as drought, the most important limitation to yield stability and plant harvest product quality which often lead to hydromineral nutritional stress. The capacity of plants to extract nutrients and water from a given volume of soil depends on root system architecture and on intrinsic factors such as the production of root exudates and the efficiency for resource uptake and transport. This capacity is largely influenced by complex root-soil interactions in the rhizosphere, such as relationships with beneficial microorganisms, but are still poorly understood and not taken into account in breeding. As such it is mandatory to take advantage of beneficial plant - biotic interactions to increase plant performance, lower the use of fertilizers and associated negative impacts on environment adopting an agroecology approach. Reaching the awaited promotion of bioavailability of mineral elements for plants, avoiding competition between plants and the microbiome and so promoting plant growth under low input cropping systems needs concerted approach, disciplines and methods. A selection of ongoing research projects, on various crops will illustrate how phenotyping tools and methods are being federated with a range of disciplines to identify the genetic and physiological determinants of root traits, both morphological and functional, and their plasticity to abiotic constraints, relevant to improve plant performance in low input cropping systems, via improved cultivars and the valorisation of interactions with beneficial microbes, in fine for the choice of innovative varieties by breeders.

International audience

National audience; In the current context of climate change, periods of water deficit occur more frequentlyalong the crop cycle, leading to high yield losses. To limit the negative impact of recurrentwater deficits, plants can adapt, via the mobilization of “stress memory”, allowing them torespond to a subsequent stress in a faster and/or more intensive manner. After a first stressevent, plants can keep an imprint of this stress via the induction of epigenetic (e.g. memorygene regulation), physiological (e.g. stomatal closure) and molecular (e.g. compoundaccumulation) changes. When maintained between two stress periods, these changes mayprepare plants for a subsequent water deficit.This work addresses the potential role of stress memory in plant adaptation to recurrent waterdeficits with a special focus on plant hydro-mineral uptake by roots. For this purpose, anexperiment was conducted on the high throughput phenotyping platform (4PMI, Dijon, France),where several frequencies of water deficits were applied to pea plants. An integrativeapproach, including a structure-function ecophysiological framework characterizing planthydromineral nutrition (nutrients and beneficial elements), enriched with root and noduletranscriptomic analyses (RNA-seq), revealed the mechanisms underlying the “memory effect”throughout the plant cycle. We will discuss the role of memory genes during recurrent stressesand plant strategies to acquire water as well as macro- and micro-nutrients more efficientlyduring recurrent stresses. This work offers the new perspective of considering plant memoryin the design of ideotypes better adapted to multiple stress events in a context of climatechange.Study conducted in the framework of the EAUPTIC project, supported by the “Fond UniqueInterministériel" (n° 3870401/1), BPIFrance (n° DOS0097244/00), the Regional Council ofBurgundy (n° DOS0133465/00), Dijon Metropole (n° CONV-DM2018-118-20180820), and theFonds Européen de Développement Régional (n° 2018-6200FEO003S01889).

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