Unraveling endophytic fungal communities: Diversity, global biogeography, and biological activities

Abstract

Endophytes are microorganisms, including bacteria, fungi, and actinomycetes, which colonize the internal tissues of plants for at least part of their life cycle without causing apparent disease symptoms or adverse effects to the host. Endophytic fungi, also regarded as plant-associated fungi, include a diverse collection of microorganisms normally found in plant tissues or intercellular gaps and are rich in biodiversity. There are five major phyla of endophytic fungal communities, namely, Ascomycota, Basidiomycota, Mucoromycota, Glomeromycota, and Chytridiomycota. Fungal endophytes contribute to plant growth and sustainable productivity by improving host tolerance to diverse biotic and abiotic stresses. Endophytic fungi perform remarkable functions in the environment, including stress tolerance (abiotic and biotic), eco-adaptation, boosting plant growth and development, and maintaining their host’s health. Endophytes have the ability to modify phytochemical profiles, mediate the expression of plant functional traits, and reduce a plant’s susceptibility to disease. The beneficial activities of endophytes are mediated by the synthesis of secondary metabolites and enzymes, regulation of host physiological functions, and their ability to act as biological control agents against pests and plant pathogens. The lack of understanding surrounding endophyte biogeography has hindered both scientific and applied research concerning endophytes. Since they are relatively undiscovered, endophytic fungi may be sources of novel products that can be utilized in industry, agriculture, and medicine. So, this review mainly focuses on the diversity and biogeography of endophytic fungal communities and their potential contribution to promoting agro-environmental sustainability.