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.研究背景：频发的干旱严重威胁生态系统结构与植物生长。根系分泌物（root exudates）可调控根际微生物群落（rhizosphere microbial communities），助力植物适应非生物胁迫（abiotic stresses）；然而在木本植物体系（woody plant systems）中，干旱胁迫下关键代谢物（keystone metabolites）与核心微生物组（core microbiome）的互作机制仍尚未明晰。刺槐（Robinia pseudoacacia，英文名black locust）是黄土高原生态修复的先锋树种，其干旱适应背后关联"关键代谢物-核心微生物组-植物抗逆性"的整合机制亟待深入研究。 本研究以黄土高原沿南北干旱梯度分布的两个生态区中的成熟刺槐林分为研究对象（北部干旱易发区LPN、南部相对湿润区LPS），采用非靶向代谢组学（untargeted metabolomic profiling）分析根际代谢物组成，结合16S rRNA扩增子测序（16S rRNA amplicon sequencing）解析微生物群落结构；通过共现网络分析探究关键代谢物与核心微生物组的关联，并整合土壤理化性质与气候数据，明确环境驱动因子。