Response of Rhizoctonia solani to biocontrol agent Bacillus velezensis SNZC ‐48 by phenotypic and transcriptome analysis biocontrol of rice sheath blight by antagonistic bacterium

BACKGROUND: Rice sheath blight (RSB), caused by Rhizoctonia solani, is an important disease affecting rice production. Although chemical control remains the predominant method of control, the excessive use of chemical agents does not align with modern agricultural development trends. Biological control is an effective measure for reducing and replacing chemical control. RESULTS: In this study, the biocontrol strain, SNZC-48, was isolated from the roots of Conyza canadensis, and its inhibition zone against R. solani was 28.33 mm. The inhibition rate against R. solani reached 98.86% on potato dextrose agar plates containing 30% culture filtrates of SNZC-48. In addition, it had a good inhibitory effect on the mycelial growth of the other 11 pathogens. In the field control experiment, the preventive effects of SNZC-48 on Nipponbare and Beigeng 1705 were 73.26% and 72.43%, respectively, and the curing effects of SNZC-48 were 72.38% and 71.23%, respectively. SNZC-48 was identified as Bacillus velezensis through morphological, physiological, biochemical, and molecular analyses. Fluorescence observations and re-separation experiments demonstrated that SNZC-48 could stably colonize rice roots, stems, leaves, and rhizosphere soil. Transcriptome data analysis revealed that SNZC-48 treatment may affect the synthesis and function of the cell membrane of R. solani and reduce its antioxidant defense ability, eventually causing reactive oxygen species accumulation and cell damage. CONCLUSION: The results indicate that the biocontrol strain SNZC-48 has the potential to be used as a biocontrol agent for RSB and preliminarily explain the control mechanisms of how strain SNZC-48 impairs R. solani. © 2026 Society of Chemical Industry.