Effect of plant presence on the soil microbiota under varying water availability and environmental contexts

The on-going climate change has important consequences on water availability status in soils, ranging from highly limited during extended droughts to excessive during intense rainfall events. This has a direct impact on soil microbial communities and plant growth. However, it remains unclear how plant presence affects soil microbiota capacity to react to varying water levels. The plant could indeed either amplify or buffer these effects on the soil microbiota, for instance via competition for water, or stabilization of the community structure via constant rhizodeposition.To address this, we grew Brassica juncea and Brachypodium distachyon in two contrasted soils. Their rhizosphere microbiotas were then extracted and reinoculated in the same soils with or without the plant to assess their stabilization role under varying water levels. After four weeks plant morphology, biomasses, relative water content and root aggregated soil were measured, and soil bacterial and fungal communities were analysed by amplicon sequencing.