Deepak Kumar, Krishna Sundari Sattiraju, M. S. Reddy
The plant holobiont comprises the host plant and its associated microbial communities functioning together as a single ecological and evolutionary unit that influences plant health, productivity, and environmental adaptability. Endophytes, formerly classified primarily as plant growth-promoting agents, are currently gaining traction as integral components of plant-associated microbiomes such as the rhizobiome and phytobiome. They can alter host-mediated root exudation patterns, microbial community structure, and nutrient dynamics within the rhizosphere. Endophytes play an important role in modulating host signaling pathways, thus influencing plant growth. Various mechanisms by which endophytes contribute to improved plant performance include soil microbiome dynamics, carbon sequestration, and strengthening the host's ability to tolerate abiotic stressors. Multi-omics, single-cell, and systems-level approaches integrated with CRISPR, metabolic engineering, and AI, together with systems biology, guided by in vitro and field studies, support predictive modeling and provide evidence for the evolution of system-driven strategies for developing effective bioinoculants. This review highlights the potential of endophytes to serve as a scalable and sustainable component of climate-resilient and regenerative agricultural systems, while acknowledging ecological variability and field-level constraints.