The cultivation of legumes shows promise for the development of sustainable agriculture, but yield instability remains one of the main obstacles for its adoption. Here, we tested whether the yield stability (i.e., resistance and resilience) of pea plants subjected to drought could be enhanced by soil microbial diversity. We used a dilution approach to manipulate the microbial diversity, with a genotype approach to distinguish the effect of symbionts from that of microbial diversity as a whole. We investigated the physiology of plants in response to drought when grown on a soil containing high or low level of microbial diversity. Plants grown under high microbial diversity displayed higher productivity and greater resilience after drought. Yield losses were mitigated by 15% on average in the presence of high soil microbial diversity at sowing. Our study provides proof of concept that the soil microbial community as a whole plays a key role for yield stability after drought even in plant species living in relationships with microbial symbionts. These results emphasize the need to restore soil biodiversity for sustainable crop management and climate change adaptation.

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Background Drought stress negatively affects plant growth and productivity. Plants sense soil drought at the root level but the underlying mechanisms remain unclear. At the cell level, we aim to reveal the short-term root perception of drought stress through membrane dynamics. Results In our study, 15 Medicago truncatula accessions were exposed to a polyethylene glycol (PEG)-induced drought stress, leading to contrasted ecophysiological responses, in particular related to root architecture plasticity. In the reference accession Jemalong A17, identified as drought susceptible, we analyzed lateral roots by imaging of membrane-localized fluorescent probes using confocal microscopy. We found that PEG stimulated endocytosis especially in cells belonging to the growth differentiation zone (GDZ). The mapping of membrane lipid order in cells along the root apex showed that membranes of root cap cells were more ordered than those of more differentiated cells. Moreover, PEG triggered a significant increase in membrane lipid order of rhizodermal cells from the GDZ. We initiated the membrane analysis in the drought resistant accession HM298, which did not reveal such membrane modifications in response to PEG. Conclusions Our data demonstrated that the plasma membranes of root cells from a susceptible genotype perceived drought stress by modulating their physical state both via a stimulation of endocytosis and a modification of the degree of lipid order, which could be proposed as mechanisms required for signal transduction. Electronic supplementary material The online version of this article (10.1186/s12870-019-1814-y) contains supplementary material, which is available to authorized users.