Plant growth-promoting traits and activation of defense enzymes in traditional rice variety by fungal endophytes isolated from seeds of indigenous rice cultivars of Northeast India

Abstract

The present investigation was carried out to expound on the role of seed borne endophytic fungi isolated from native rice cultivars of North East India. Altogether 226 fungal isolates were obtained from the surface-sterilized seeds of the 10 selected rice cultivars. The major isolates were species of Curvularia, Aspergillus, Fusarium, Gliocladium, Mucor, Penicillium, Bipolaris, Basidiobolus, Periconia, and non-sporulating mycelia sterilia. Principal Component Analysis (PCA) revealed dominance of Fusarium and Curvularia with high degree of colonization in Ampack and Chakhao rice cultivars. Altogether 84.61% of the isolates, showed siderophores activity on CAS agar medium and 76.92% of the isolates showed phosphorus solubilization activity. The result indicated that 84.61% of the isolates showed positive for ammonia production and interestingly grew in nitrogen-deficient Jensen's agar medium. The fungal isolates BD9, KON7, AM34, AM10, and Mycelia sterilia exhibited the highest antagonistic activity against rice pathogen Magnaporthe grisea. Enhanced production of peroxidase, polyphenol oxidase, chitinase, and superoxide dismutase enzyme was observed when a traditional rice plant was inoculated with a consortium made of fungal isolates AM34 and AM10 (Treatment 3). This combination exhibited a moderate increase in catalase production. Consortia made of other fungal isolates were not efficient in producing any defense enzymes. The isolates AM10, AM28, AM16, AM34, and AN 20 were identified as Fusarium annulatum, Daldinia eschscholtzii, Montagnula scabiosae, Fusarium redolens and Aspergillus flavus respectively based on microscopic and molecular characterization