drought wheat microbiome

The co-evolutionary relationships between plants and their microbiomes play a crucial role in maintaining plant health and productivity under biotic and abiotic stresses. Yet, drought effects on plant microbiomes and its implications for drought resistance remain poorly understood. Here we tested if drought-induced microbial changes in plants improve host adaptability to drought conditions. Using wheat as a model plant, we conducted multiple experiments employing a range of genomics and culture-dependent methods to analyse soil, root and rhizosphere microbiomes, their functions, and interactions with rhizosphere metabolomes and plant phenotypes. We found that drought triggered microbial enrichments, notably, Streptomyces coeruleorubidus (+30.04-fold in roots; +5.04-fold in the rhizosphere), Leifsonia shinshuensis and Burkholderia spp. in plant microbiomes compared with well-watered conditions. Drought also increased levels of 4-oxoproline in the rhizosphere, which could enhance osmotic resistance for plants and microorganisms. Consistently, genes facilitating microbial responses to drought, especially rimJ encoding N-terminal acetyltransferase, were enriched, correlating with the microbial abundances and 4-oxoproline levels. Re-introduction of S. coeruleorubidus and L. shinshuensis, to the plant system promoted host drought resistance via alterations of plant physiology and gene expressions. These beneficial changes were supported by further drought-legacy-effect experiments, where both plant biomass (+91%) and yield (+49%) increased in the subsequent growth cycle under drought. Overall, this study provides novel evidence and mechanistic knowledge for drought-induced microbial and metabolite enrichments improving plant adaptation to abiotic stresses, and can inform future development of bio-based tools to mitigate drought effects.