Biocontrol potential of root rot in Polygonatum sibiricum by Bacillus velezensis Y24 and its genome analysis

• Bacillus velezensis Y24 represents a promising biocontrol agent against P. sibiricum root rot. • Lipopeptides from the Y24 CFS inhibited Fusarium oxysporum . • Y24 LPs destroyed the mycelial morphology of F. oxysporum . • Y24 genome contains 13 BGCs with potential for diverse antimicrobial synthesis. Polygonatum sibiricum root rot, caused by Fusarium oxysporum , is a severe soil-borne disease in P. sibiricum cultivation. In this study, a high-efficiency biocontrol bacterium, Bacillus velezensis Y24, was isolated from healthy P. sibiricum plants, and its biocontrol potential was evaluated. Strain Y24 exhibited an in vitro inhibition rate of 70.63 % against F. oxysporum , while its cell-free supernatant (CFS) showed an inhibition rate of 50.90 %. The EC 50 of lipopeptides (LPs) against F. oxysporum was 0.134 mg/mL. After treatment with 0.2 mg/mL LPs, the hyphae of F. oxysporum showed swelling, deformation, and fragmentation, with conidial germination significantly inhibited. The colonization ability assessment indicated that strain Y24 exhibits a strong biofilm-forming capacity, with the most prominent biofilm-forming ability in MSGG medium. Analysis of its whole-genome sequencing using antiSMASH revealed that strain Y24 contains 13 biosynthetic gene clusters (BGCs) for antimicrobial peptide synthesis, among which 9 BGCs show high similarity to known functional gene clusters, including Bacillaene, Fengycin, and Difficidin. Moreover, the genome of strain Y24 also has the potential to synthesize various extracellular proteases and cellulases. In pot experiments, the control efficacy of strain Y24 against P. sibiricum root rot reached 81.51 %. This study its key antifungal substances, laying a solid research foundation for green control of P. sibiricum root rot.