Diversity and functions of secondary metabolites secreted by epi-endophytic microbes and their interaction with phytopathogens

Abstract The term “endophyte” was first introduced by De Bay in 1886 to explore the symbiotic microbiota to contain the plant diseases like probiotic microbiota in human being. The modern intensive farming system enhanced the use of chemical synthetic pesticides to increase the crop production in agri-horti ecosystems for many decades. Due to the hazardous effect of pesticides on soil health, human health, and the environment, this is likely to be limited in future. As an alternative strategy, the secondary metabolites produced by agriculturally important microorganisms are explored, which are residing in the host plants as epiphytes and endophytes and play an important role in improving the quality of the crops. Microorganisms synthesize enzymes, compounds either alone or in association with the host plants, which are eco-friendly, toxic to plant pathogens, and do not harm human beings and other living organisms. Inoculation with endophytes modulates the synthesis of bioactive compounds with high pharmaceutical properties in addition to plant growth promotion. In this review, we have focused on the need for exploration of alternative microbial habitats for isolating novel microbes with chemical and functional diversity.