Response of Ginkgo Biloba Rhizosphere Metabolites and Microbial Community Structure to Annual Precipitation Gradient-Shift in Driving Factors and Potential Growth Promoting Rhizobacteria Analysis

Ginkgo biloba L., a relict tree species with strong ecological resilience, shows high adaptability to precipitation variation, yet the mechanisms linking its rhizosphere metabolites and microbial communities to natural precipitation gradients remain unclear. This study investigated five sites along an eastern China precipitation gradient (651.7-1719 mm; Jinan, Pizhou, Taixing, Hangzhou, Ningbo) using integrated metabolomics and microbiomics. Results revealed that precipitation significantly shaped rhizosphere metabolite profiles: organic acids increased (22.7%-25.9%) with higher precipitation, while lipids increased (38.9%-39.2%) under reduced and increased rainfall. The main drivers of bacterial community assembly shifted from conventional nutrients (total potassium, available phosphorus, available potassium) under baseline conditions to metabolites (organic acids, lipids) under altered precipitation. Two bacterial orders, Bacillales and Rhizobiales, responded significantly to precipitation changes, with Bacillales enriched under extreme conditions as key growth-promoting taxa enhancing stress tolerance in ginkgo. Overall, precipitation indirectly influenced bacterial communities by reshaping metabolite composition. Under extreme moisture conditions, metabolites replaced soil nutrients as dominant drivers, indicating that ginkgo adapts by modulating root exudates to recruit beneficial microbes, providing potential targets for rhizosphere microbial engineering.