PLANT–MICROBIOME INTERACTIONS AS A NOVEL AXIS FOR SECONDARY METABOLITE DIVERSIFICATION

Plants harbor diverse microbial communities—comprising endophytic and rhizospheric microorganisms—that profoundly influence host secondary metabolism. This review critically examines the emerging evidence for plant-microbiome interactions as a novel axis for secondary metabolite diversification. We synthesize current understanding of the mechanisms by which endophytic and rhizospheric microbes modulate the biosynthesis, structural modification, and biological potency of host plant secondary metabolites. Microbial communities influence plant secondary metabolism through multiple strategies, including activation of plant immune signaling pathways, secretion of phytohormones, nutrient modulation, and direct biotransformation of plant-derived precursors. The resulting metabolic alterations encompass enhanced production of existing bioactive compounds, generation of novel derivatives through microbial enzymatic activity, and discovery of previously unknown metabolites. Furthermore, we assess the implications of these interactions for drug discovery, sustainable agriculture, and the conservation of medicinal plant resources. Despite significant progress, substantial research gaps remain regarding the mechanistic basis of microbial influence on plant metabolism and the translation of these interactions into biotechnological applications. This review provides a comprehensive framework for understanding plant-microbiome interactions in secondary metabolism and identifies promising directions for future research.