Strong Opponent of Walnut Anthracnose- Bacillus velezensis and Its Transcriptome Analysis.

Walnut is a significant economic tree species worldwide. Walnut anthracnose, caused by the pathogen , greatly reduces walnut production and economic benefits. Our study showed that effectively halted the growth of , inducing noticeable abnormalities such as hyphal breakage and distortion, thereby curtailing the pathogen's virulence. A 50-100 times dilution of fermentation broth, applied every two to three days, served as an efficient protective layer for walnut leaves and fruits against infection. Transcriptomic analysis of unveiled its dynamic response against . On the second day, upregulated a significant number of differentially expressed genes related to the synthesis of metabolic products, amino acid biosynthesis, and motility. On the fourth day, continuous synthesis of metabolic products and amino acids, along with differential expression of spore-related genes, was observed. By the sixth day, the focus shifted towards environmental adaptation and carbon source utilization. Throughout the process, likely employed strategies such as the release of metabolic products, increased chemotaxis, and nutrient competition to exert its antagonistic effect on . Fluorescence quantitative results showed that 15 primer pairs were up-regulated and 15 were down-regulated, with a 100% similarity rate to transcriptome sequencing results, confirming their authenticity. These findings provided a foundation for the widespread application of as a biocontrol agent in agriculture and forestry.