Keystone metabolites drive the core microbiome to confer plant stress resilience in Robinia pseudoacacia

Research Background: Frequent droughts severely threaten ecosystem structure and plant growth. Root exudates regulate rhizosphere microbial communities to facilitate plant adaptation to abiotic stresses; however, the interaction mechanisms between keystone metabolites and the core microbiome under drought stress remain poorly understood in woody plant systems. Robinia pseudoacacia (black locust), a pioneer species for ecological restoration on the Loess Plateau, the integrated mechanism linking "keystone metabolites–core microbiome–plant stress tolerance" underlying its drought adaptation urgently needs investigation.
Taking mature R. pseudoacacia stands in two ecological zones with a north-south drought gradient on the Loess Plateau (the northern drought-prone region, LPN; the southern relatively humid region, LPS) as research objects, untargeted metabolomic profiling was used to analyze rhizosphere metabolite composition, combined with 16S rRNA amplicon sequencing to characterize microbial community structure. Co-occurrence network analysis was performed to explore the associations between keystone metabolites and the core microbiome, and soil physicochemical properties and climatic data were integrated to identify environmental driving factors.