Root exudates and microbial metabolites: signals and nutrients in plant-microbe interactions

Plant roots meticulously select and attract particular microbial taxa from the surrounding bulk soil, thereby establishing a specialized and functionally diverse microbial community within the rhizosphere. Rhizosphere metabolites, including root exudates and microbial metabolites, function as both signals and nutrients that govern the assembly of the rhizosphere microbiome, playing crucial roles in mediating communications between plants and microbes. The environment and their feedback loops further influence these intricate interactions. However, whether and how specific metabolites shape plant-microbe interactions and facilitate diverse functions remains obscure. This review summarizes the current progress in plant-microbe communications mediated by chemical compounds and their functions in plant fitness and ecosystem functioning. Additionally, we raise some prospects on future directions for manipulating metabolite-mediated plant-microbe interactions to enhance crop productivity and health. Unveiling the biological roles of specific metabolites produced by plants and microbes will bridge the gap between fundamental research and practical applications.