枯草芽孢杆菌XH-1对小麦赤霉病防效及全基因组测序分析OA

[Objective]The study aims to analyze the antagonistic activity,antifungal effects,and molecular mechanisms of Bacillus subtilis XH-1(hereafter XH-1)against Fusarium graminearum PH-1(hereafter PH-1),the primary pathogen causing Fusarium head blight(FHB).It also seeks to identify the functional genes and metabolic pathways associated with the antifungal properties of XH-1,thereby provi-ding data support for the development and application of this strain in the biological control of FHB.[Method]The antagonistic effect of XH-1 against PH-1 was evaluated via plate confrontation assay.PH-1 was treated with sterile fermentation broth of XH-1 at gradient concentrations to determine the antifungal activity of the broth and observe the resulting mycelial morphology.The whole genome of XH-1 was assembled u-sing a hybrid strategy and second-generation and third-generation sequencing technologies combined with the Unicycler software.Gene func-tion annotation was conducted using databases including NR,COG,KEGG,CAZy,VFDB and CARD,and secondary metabolite biosynthetic gene clusters(BGCs)were predicted concurrently.[Result]Plate confrontation assay showed that XH-1 exhibited antagonistic activity a-gainst PH-1,with a growth inhibition rate of 61.63％.The fermentation broth of XH-1 significantly inhibited the growth of PH-1 in a dose-de-pendent manner,with high concentrations inducing mycelial swelling and moniliform distortion.The genome of XH-1 was 4.22 Mb in size and had a GC content of 43.51％,encoding a total of 4434 genes.Nine BGCs were identified.Functional annotation revealed the presence of sid-erophore synthesis genes(dhbA,dhbB,dhbC,dhbE,dhbF),glycoside hydrolase genes(e.g.,chitinase genes),and spore formation-related genes,and the environmental risk of drug-resistant genes was assessed to be low.[Conclusion]XH-1 can effectively inhibit the mycelial growth of PH-1.Integrated genomic analysis suggests that XH-1 may exert a multi-dimensional synergistic inhibitory effect by secreting antimi-crobial secondary metabolites,competing for nutrients,enzymatically degrading the pathogen's cell wall,and enhancing its own stress resist-ance.This strain exhibits excellent potential for the biological control of FHB,providing a valuable microbial resource and theoretical founda-tion for developing commercial biocontrol agents.