Biosynthetic Mechanisms of Secondary Metabolites Promoted by the Interaction Between Endophytes and Plant Hosts

Abstract

Endophytes is a kind of microorganism resource with great potential medicinal value. The interactions between endophytes and host not only promote the growth and development of each other but also drive the biosynthesis of many new medicinal active substances. In this review, we summarized recent reports related to the interactions between endophytes and hosts, mainly regarding the research progress of endophytes affecting the growth and development of host plants, physiological stress and the synthesis of new compounds. Then, we also discussed the positive effects of multiomics analysis on the interactions between endophytes and their hosts, as well as the application and development prospects of metabolites synthesized by symbiotic interactions. This review may provide a reference for the further development and utilization of endophytes and the study of their interactions with their hosts.

Keywords: biosynthesis mechanism; endophytes; growth and development; interactive relationships; secondary metabolites.

FIGURE 1

Signal response mechanisms for promoting (+) or inhibiting (–) plant – microbial interactions. Exogenous microorganisms release action factors to infest plants, which respond with gene expression and release metabolites such as antibiotics and hormones (SA, JA, GA, ET, and ABA) to interfere with the infestation to protect themself.

FIGURE 2

Endophytes affect host growth. Endophytes release factors that act on host cells, which express RNA-induced silencing complex (RISC) genes and silence specific genes, thereby regulating the invasion process of endophytes. (A) Under the action of Nod factor, rhizobia formed root nodules and fixed N₂. (B) AMF form clumped mycorrhizae (AM) under the action of Myc factors, which promote host uptake of inorganic ions (C, P, N, etc.) and regulate the root environment. (C) Some endophytes are able to produce hormones (SA, JA, GA, ET, ABA, etc.) that promote host growth.

FIGURE 3

Endophytes regulate the tolerance of plants to stress. (A) Under stress environment, endophytes can produce exogenous signals and quickly activate plant PRRs membrane receptors. On the one hand, they activate the downstream MAPKs level connection On the other hand, they regulate the intracellular Ca²⁺ concentration. (B) Under the action of exogenous signal of endophytes, membrane receptors such as CPCRs and RLKs are activated to induce downstream reaction. Cascade signaling is transmitted in the nucleus to promote the expression of relevant response genes, so as to improve the ability of host in immune response, repair damage and reduce stress.