Boosting Plant Immunity: The Functional Role and Mechanism of Arbuscular Mycorrhizal Fungi in Resistance

In plant-microorganism rhizosphere interactions, the Arbuscular Mycorrhizal Fungi (AMF) play a pivotal role in fortifying plant defense mechanisms vs deleterious pathogens. This intricate interplay is reinforced by the plant innate capacity to discriminate between symbiotic AMF and pathogenic entities, underpinned by complex molecular signalling cascades and receptor-mediated responses. AMF colonization initiates a series of events encompassing shifts in gene expression, modulation of protein profiles, and alterations in metabolite composition, mediated by bioactive compounds such as strigolactones and Myc-factors. Successful recognition culminates in substantial cellular reorganization, notably the formation of arbuscules within plant cells, signifying a harmonious symbiotic union. Concomitantly, plants have evolved discerning receptor complexes tailored to differentiate between AMF and pathogenic incursions, orchestrating a meticulous equilibrium between immune responses and symbiotic associations. AMF-mediated biocontrol represents a pivotal facet of this mutualistic partnership. These fungi function as biocontrol agents, shielding plants against an array of soil-borne adversaries, including bacteria, nematodes, and phytopathogenic fungi. The intricate mechanisms underpinning AMF-mediated biocontrol encompass induced systemic resistance, alterations in root morphological traits, biochemical modifications, and perturbations within the rhizospheric microbial community. This review elucidates the multifaceted molecular, physiological, and ecological dimensions of the symbiotic interplay between plants and AMF, unveiling the remarkable mechanisms augmenting plant defense strategies and restraining soil-borne pathogens.