Regulation of secondary metabolites accumulation in medicinal plants by rhizospheric and endophytic microorganisms

Medicinal plants contain numerous bioactive secondary metabolites (SMs) that can be used for the treatment and prevention of diseases. SM concentration is a crucial standard for evaluating the quality of medicinal plants. SM accumulation is affected by multiple factors, including genetic background, climate, soil physical and chemical properties, and environmental changes. In recent years, increasing studies have indicated that rhizospheric and endophytic microorganisms, play an essential role in regulating the accumulation of SMs in medicinal plants. While some microorganisms establish symbiotic relationships with medicinal plants to promote plant growth. Other microorganisms can directly synthesize SMs or promote plant SM biosynthesis through multiple strategies, such as activating plant immune signaling pathways and secreting plant hormones into host cells to manipulate hormone-mediated pathways. In contrast, SMs may improve plant resistance to environmental stresses, thereby affecting the composition of rhizospheric and endophytic microorganisms. In this review, we summarized the recent progress in understanding the role of microorganisms in regulating SM accumulation in medicinal plants. Further studies should focus on the application of utilizing microorganisms to enhance the accumulation of bioactive SMs in medicinal plants.