Plant growth-promoting endophyte Nigrospora oryzae mitigates abiotic stress in rice (Oryza sativa L.)

Climate change has severely impacted crop productivity. Nascent technologies, such as employing endophytic fungi to induce crop adaptogenic changes, are being explored. In this study, 62 isolates of fungi existing as endophytes were recovered from different parts of a drought-resistant rice variety and screened for salinity and drought tolerance. Nigrospora oryzae #2OSTUR9a exhibited in vitro antioxidant potential, indole acetic acid (351.01 ± 7.11 µg/mL), phosphate solubilisation (PI 1.115 ± 0.02), siderophore (72.57% ± 0.19%) and 1-aminocyclopropane-1-carboxylate deaminase production (305.36 ± 0.80 nmol α-ketobutyrate/mg/h). To the best of our knowledge, this is the first report on salinity and drought stress mitigation in rice plants by endophytic N. oryzae. In treated plants under salinity stress, the relative water, chlorophyll, phenolic and osmolyte content increased by 48.39%, 30.94%, 25.32% and 43.67%, respectively, compared with their respective controls. A similar trend was observed under drought stress, where the above parameters increased by 50.31%, 39.47%, 32.95% and 50.42%, respectively. Additionally, the antioxidant status of the treated plants was much higher because of the enhanced antioxidant enzymes and reduced lipid peroxidation. Our findings indicate the ability of N. oryzae to effectively mitigate the impact of stress, thereby enabling the rice plant to sustain stress conditions.