Signal Molecules Regulate the Synthesis of Secondary Metabolites in the Interaction between Endophytes and Medicinal Plants

Signaling molecules act as the links and bridges between endophytes and host plants. The recognition of endophytes and host plants, the regulation of host plant growth and development, and the synthesis of secondary metabolites are not separated by the participation of signaling molecules. In this review, we summarized the types and characteristics of signaling molecules in medicinal plants and the recent processes in intracellular conduction and multi-molecular crosstalk of signaling molecules during interactions between endophytic bacteria and medicinal plants. In addition, we overviewed the molecular mechanism of signals in medical metabolite accumulation and regulation. This work provides a reference for using endophytic bacteria and medicinal plants to synthesize pharmaceutical active ingredients in a bioreactor.