ABSTRACT
Plants are continuously exposed to an enormous amount of external stimulus. Being sessile, they have to deal with various and complex types of interactions involving numerous environmental factors. Fungal endophytes are major classes of fungal symbionts that establish different forms of symbiotic interactions with host plants such as commensalism, mutualism, and parasitism. In a mycorrhizal association, the fungus colonizes the host plant’s root tissues, either intracellularly as in the case of arbuscular mycorrhizal fungi, or extracellularly as in ectomycorrhizal fungi. Plants that are symbiotically associated with endophytic fungi rapidly activate host stress response systems when exposed to stress. Legumes play a very important role in many agricultural systems, providing high protein grains and herbage as well as maintaining and improving soil fertility. In fact, a large number of studies have illustrated the importance of useful microbes in crop growth and stress tolerance of crop plants.
