Plants use rhizosphere metabolites to regulate soil microbial diversity

Abstract Specific metabolites and secondary metabolites produced by plants and soil microbes play key roles in regulating organismal behaviour. At present, the variations in soil microbial communities mediated by plant rhizosphere metabolism in arid environments are still poorly understood. Therefore, we investigated the rhizosphere soil (RS) and bulk soil (BS) associated with five plant species adapted to the climate in the Mu Us Sandy Land and analysed the chemical composition of soil metabolites, microbial community composition and diversity, edaphic factors, and their relationships. Some metabolites with ecological functions (such as fatty acids, monoacylglycerides and diterpenoids) were detected in the RS and BS of the five plants. Correlation analysis results show that fatty acids and diterpenoids were significantly negatively correlated with drought‐adapted bacterial (Actinobacteria, Chloroflexi) and fungal taxa (class Glomeromycetes and family Nectriaceae), and the bacterial class Rubrobacteria and two fungal phyla Ascomycota and Glomeromycota were significantly negatively correlated with fatty acids and diterpenoids, respectively. Redundancy analysis (RDA) and Monte Carlo permutation results confirm that fatty acids and diterpenoids played critical roles in the variation in the soil microbial communities. Although soil edaphic factors (such as microbial biomass carbon and basal respiration) played important roles in shaping the microbial community, the results of partial least squares path modelling (PLS‐PM) show that plant‐mediated rhizosphere metabolism was the primary factor that affected microbial alpha and beta diversities. We conclude that plants under drought stress regulate microbial community structures by releasing certain fatty acids and secondary metabolites (such as diterpenoids). In addition, the bioactive metabolites released from the rhizosphere affect the soil microbial community more significantly and directly than edaphic factors. Overall, our study provides insight into the underground ecological processes mediated by plant rhizosphere metabolism.