Microbial elicitors to metabolic reprogramming: an integrative model of plant-microbe interactions

Plant growth, soil health, and crop productivity with nutritional quality can be significantly enhanced by employing microbial consortia that incorporate diverse microorganisms with complementary functions. Plants produce various types of secondary metabolites such as terpenoids, alkaloids, phenolics, essential oils, and other metabolites through various cellular mechanisms, which are often stimulated by microbial interactions. These metabolites exert beneficial effects on plants and perform multiple roles in agriculture, contributing significantly to growth and economy. This review summarizes microbial consortia-mediated enhancement of plant health and their intricate interactions with host plants. Beneficial microbes of a consortium trigger complex signaling cascades leading to a dynamic regulatory strategy through which plants enhance their secondary metabolite synthesis. Secondary messengers and hormonal cross-talk further integrate the signal to transcription factors, which play a central role in activating or repressing the key genes of the metabolic pathways. Thus, the interplay of microbial signal, secondary messengers, hormonal cross-talk, and key metabolite genes forms the basis of plant secondary metabolite biosynthesis. In addition, recent advances in systems microbiology, including metagenomics, metatranscriptomics, and metabolomics, have enabled a holistic understanding of microbial community dynamics and their collective role in regulating secondary metabolism.