Abstract:

This study aimed to elucidate the inhibitory mechanisms, genomic features, and taxonomic classification of the antagonistic biocontrol strain CY-1 against Magnaporthe oryzae, the pathogenic agent of rice blast. The antifungal activity of CY-1 fermentation broth, prepared under different concentrations and temperature conditions, was evaluated against M. oryzae by assessing its effects on mycelial growth and biomass. Additionally, whole-genome sequencing was used to determine the taxonomic classification of strain CY-1 and to characterize its functional gene repertoire. The results demonstrated that a 20-fold dilution of the CY-1 fermentation broth exhibited 100.00% inhibition of mycelial growth against M. oryzae. In contrast, the highest inhibition of mycelial biomass (87.89%) was observed at a 100-fold dilution. The inhibition rate of the CY-1 fermentation broth subjected to various temperature treatments was significantly lower than that of the untreated control. Genomic analysis revealed that CY-1 was enriched with diverse gene clusters involved in secondary metabolite biosynthesis, suggesting that its antifungal activity may be mediated through the secretion of antibiotic-like compounds. Comparative genomic analysis confirmed that the strain was Bacillus subtilis. In conclusion, strain CY-1 demonstrates significant biocontrol potential against rice blast. It represents a promising biocontrol resource, providing both theoretical foundations and material support for the green management of this disease.

Key words: Bacillus subtilis, Magnaporthe oryzae, antagonistic mechanism, secondary metabolites, genome analysis, biocontrol