Deciphering Role of Endophytes in Plant Defences and Biotic Stress Resilience Across Families

Plant families generate distinct repertoires of specialised metabolites that govern their biotic interactions. Endophytes strengthen host plant defence mechanisms and tolerance to biotic challenges by upregulating metabolite biosynthesis, modifying precursor compounds into more potent forms, or by directly synthesising analogous defence metabolites themselves. This review examines the complex relationships between endophytes and their host plants, with a focus on their colonisation strategies, interactions, and contribution to plant immunity. It explores the diverse mechanisms through which endophytes augment plant defences, including the production of specialised metabolites, induction of systemic resistance, and direct antagonism against pathogens and herbivores. Accordingly, this study provides a comprehensive account of role of endophytes in protecting plants against multiple biotic stressors, rather than isolated threats. It further addresses a critical knowledge gap by highlighting how synergistic interactions between endophytic microbes and plant family-specific specialised metabolites shape plant immunity. By examining these unique plant-endophyte interactions across different plant families, the review offers deeper insight into the ecological and functional significance of endophytes in plant defence. Thus, it paves the way for targeted applications of endophytes in sustainable agriculture, where specific microbial strains can be harnessed to naturally improve plant protection and productivity.