Isolation and Functional Characterization of Culture-Dependent Endophytes Associated with Vicia villosa Roth

In a natural ecosystem, endophytic fungi in the internal tissues of plants help to improve the growth of the host plants and to decrease the negative effects of biotic and abiotic stresses without having adverse effects. In Japan, Vicia villosa (hairy vetch), a legume plant with a high capacity to fix nitrogen, is usually used as a cover crop before soybeans to enhance the fertility and structure of the soil. This study aimed to isolate endophytic fungi associated with different tissues of hairy vetch and to evaluate their potential for growth-promoting and biocontrol effects in plants. Thirty-three fungal endophytes belonging to Ascomycota and Basidiomycota were isolated from the leaf, stem, and root tissues of hairy vetch grown under both greenhouse and field conditions. The highest colonization frequency in both the greenhouse and field-grown hairy vetch plants was obtained from the root tissues. All isolates were checked for indole-3-acetic acid (IAA) and siderophore production. The maximum IAA content in the culture filtrate (4.21 μg mL⁻¹) was produced by the isolate hvef7 (Cladosporium cladosporioides), followed by hvef18 (Penicillium simplicissimum) (3.02 μg mL⁻¹) and hvef1 (Cladosporium pseudocladosporioides) (2.32 μg mL⁻¹). Nineteen isolates among a total of thirty-three isolates produced siderophores. Moreover, some of the isolated strains could solubilize phosphate and potassium. Most of the isolates showed antagonistic potential against Calonectria ilicicola. The results of this study show that endophytic fungi isolated from hairy vetch have the potential for application as plant growth promotion fungi (PGPF) to promote plant growth and control disease in sustainable agriculture.