In vitro and in-planta bioefficacy of bacteriome isolated from diseased leaf lesions of two contrasting rice genotypes against sheath blight disease of rice.

Abstract

Rice leaves harbor a diverse agriculturally important bacteriome. Using different dilutions and media, 20 bacterial isolates were obtained from the diseased and healthy leaves of two rice cultivars (cv. BPT-5204 and cv. Tetep). Later, the taxonomy was deduced based on the 16S rDNA sequences, which revealed 17 bacterial species belonging to 13 genera. The antifungal activity of 17 bacteria was tested against Rhizoctonia solani, which showed that Bacillus cereus, Stenotrophomonas maltophilia, and Acinetobacter lwoffii exhibited the mycelial inhibition of 65.18%, 61.85%, and 61.85%, respectively. Further, six selected bacteria (treatments: T1-T6) in three different methods of inoculation (methods: M1-M3) were tested on-field against sheath blight (ShB) for two consecutive Kharif seasons (2022 and 2023). The two-season data indicated a statistically insignificant effect of methods on the percent disease index (PDI) (40.51-42.47), whereas different bacteria treatments (T1-T6) showed a significant impact on PDI (29.15-52.08). S. maltophilia isolated from the diseased BPT-5204 was superior to all other strains in reducing the PDI (29.15). We successfully isolated and functionally characterized 17 bacteria from the artificially diseased contrasting genotypes. This study demonstrated that rice lesions naturally harbor a diverse bacterium with antifungal effects that can be used to develop non-chemical-based disease management strategies.