Secondary metabolites in plant-microbe interactions

As sessile organisms, plants are constantly exposed to various abiotic and biotic factors in their environment. Among the biotic factors, beneficial microorganisms, pathogens, and insects cause metabolic changes that affect growth and productivity. In response to these interactions and stress conditions, plants have developed sophisticated metabolic plasticity, adjusting their primary and secondary metabolic pathways. Secondary metabolites are specialized compounds that serve various ecological functions, such as defense against herbivores and pathogens, allelopathy, interaction with beneficial microorganisms, and attraction of pollinators and seed dispersers. These metabolites also act as signaling molecules in plant-microbe interactions, regulating the relationship between plants and microbes. Recent genetic and chemical research has revealed that secondary metabolites have multiple functions, acting as powerful regulators of both plant growth and defense beyond their roles in primary metabolism. This review explored the microbiome's complexity and emerging trends in understanding how microbiome composition and/or synthetic microbial community (SynCom) influence microbial and plant metabolic activities. Addressing the correlation between the varieties of microorganisms or SynCom and their metabolic profiles is crucial for elucidating the biological mechanisms that induce alterations in microbial communities and their metabolic functions within the rhizosphere and plant microbiomes. This knowledge will contribute to developing strategies to enhance beneficial interactions and mitigate the effects of pathogens that can reduce plant growth and productivity.