Ecophysiological processes underlying soybean mineral nutrition under individual or combined heat and water stresses

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.