Seed Biopriming With Pesticide‐Tolerant Bacillus simplex Strain PTB‐06 Improves Growth of Rice Plants and Manages Brown Leaf Spot Disease Through Extensive Metabolomic Perturbations

Brown leaf spot (BLS), caused by Bipolaris oryzae , is a destructive disease of rice, and the window for safe biological management of this disease needs exploration. This study explores the potential of seed priming using pesticide‐tolerant multifaceted endophytic Bacillus strains to promote rice plant growth, manage BLS, and elucidate the biochemical mechanisms underlying disease management and rice plant growth promotion. Pesticide‐tolerant Bacillus endophytes were isolated from healthy‐looking field‐grown rice plants. Based on pesticide tolerance analysis, selected Bacillus strains were used for biopriming of rice seeds. Pot experiments were conducted to assess the plant growth‐promoting potential, suppression of BLS disease, and elucidation of induced resistance mechanisms following BLS attack. Seed biopriming with Bacillus simplex strain, PTB‐06, significantly increased plant growth and mitigated BLS disease by reducing lesion number (71%) and lesion diameter (63.4%) compared with the pathogen control. PTB‐06 priming increased total phenolic content and the accumulation of defense‐related enzymes. Nontargeted metabolomic analysis revealed changes in the abundance of several metabolites and enrichment of biosynthetic pathways known to participate in plant growth and primed defense responses. This investigation highlights the biopriming potential of the B. simplex strain PTB‐06 to promote plant growth and enhanced tolerance against BLS disease of rice.