Isolation, characterization and metabolic profiling of seed endophyte B. licheniformis against Sarocladium oryzae in rice

Abstract

Rice is a vital staple food crop widely cultivated across diverse Asian agroclimatic zones. However, in recent years, the emergence of sheath rot disease, caused by Sarocladium oryzae, has severely impacted rice yields, devastating approximately half of rice production. Traditional methods of controlling plant diseases often have harmful effects on the environment and have led to the development of pathogenic resistance to various agrochemicals. In contrast, endophytes have shown great promise in managing plant diseases while enhancing plant growth and yield. The seed-associated endophyte Bacillus licheniformis has demonstrated remarkable efficacy, exhibiting a 76.47% inhibition rate against S. oryzae. Beyond its antibiotic properties, this endophyte also promotes biostimulant activities, including the production of indole-3-acetic acid (IAA), siderophores, and the utilization of ammonia (NH3). Additionally, the analysis of secondary metabolites using gas chromatography-mass spectrometry (GC-MS) revealed a diverse array of compounds, including 9,12-Octadecadienoic acid (Z, Z)-TMS derivatives, Elaidic acid-TMS, Bis(2-ethylhexyl) phthalate, Caproic acid-TMS, Diethyl phthalate, Ricinoleic acid-2TMS derivatives, Mandelic acid-2TMS, and others. These compounds exhibit significant antifungal, antiviral, larvicidal, and antibacterial activities against various plant pathogens, highlighting the potential of B. licheniformis as a sustainable and effective biocontrol agent in rice cultivation. This research underscores the critical role of endophytes in promoting sustainable agricultural practices, offering an environmentally friendly alternative to chemical control methods while effectively combating emerging plant diseases.