The Role of Endophytic Insect-Pathogenic Fungi in Biotic Stress Management

A diverse beneficial microbial community inhabits soil, with fungi comprising a major component. Fungi can establish in plants as endophytes and as a result, these plant–fungal interactions are associated with different trade-offs. Endophytic insect-pathogenic fungi (EIPF) establish a unique association with plants that can promote growth of host plants and can have detrimental effects on pest insects. The mechanisms of plant growth promotion are diverse and include nutrient exchange, plant defense modulation, and protection from pests and diseases. There is increasing interest in understanding the potential for exploiting EIPF to enhance plant productivity and tolerance to arthropod pests in agricultural systems, especially under changing climate conditions. EIPF mediate plant defense signaling through crosstalk in phytohormone-based defense systems and fine-tuning signaling pathways in the presence of stress. Secondary metabolites and other compounds in root exudates can affect the fate of EIPF–plant–stress interactions. Through these mechanisms, plants can fine-tune growth and defense in a balanced manner. Developing a better understanding of the ecology and biology of EIPF and their interactions with plants and arthropods will contribute to the achievement of agricultural sustainability.