The role of the plant microbiome in modulating plant immune responses in disease management: A review

The plant microbiome, which encompasses diverse communities of bacteria, fungi, archaea, viruses and oomycetes that colonise plant surfaces and internal tissues, is a critical determinant of plant health, resilience and productivity. This review systematically examines how plant-associated microbial communities modulate plant immune signalling pathways, with particular emphasis on pattern-triggered immunity (PTI), effector-triggered immunity (ETI), systemic acquired resistance (SAR) and induced systemic resistance (ISR). Critical evaluation of the molecular mechanisms through which beneficial microorganisms prime host defences, including microbe-associated molecular pattern (MAMP) perception, salicylate and jasmonate signalling cascades, reactive oxygen species (ROS) dynamics and transcriptional reprogramming of immune networks. Additionally, we address pathogen-mediated immune suppression strategies, including effector-driven interference, hormonal hijacking and pathobiome-associated dysbiosis, drawing explicit connections to the limitations of classical Koch's postulates in the context of community-level disease causation. This review further explores how environmental factors, including climate change, drought and agricultural intensification, reshape the microbiome composition and immune competence. Translational applications, including synthetic microbial communities (SynComs), microbiome-assisted breeding and microbiome restoration strategies, have been evaluated for field efficacy, scalability and regulatory feasibility. Current methodological limitations and future research priorities are discussed to guide the development of microbiome-informed, climate-resilient and sustainable disease management frameworks. This review highlights the transformative potential of harnessing plant microbiomes for next-generation agricultural protection strategies.