一株具有防病促生功能的贝莱斯芽孢杆菌SF327

【目的】筛选植物根际促生贝莱斯芽孢杆菌，分析菌株的生防潜力和全基因组特征。【方法】通过温室小青菜促生试验以及植物益生表型的分析，明确具有促生功能的菌株SF327。用滤纸片法测定菌株SF327对5种植物病原真菌以及4种植物病原细菌的拮抗活性。通过大田喷雾接种的方式评价菌株SF327对水稻白叶枯病的防治潜力。利用antiSMASH分析预测菌株SF327产生的二次代谢产物。通过比较基因组分析SF327与2株植物根际益生贝莱斯芽孢杆菌的代表性菌株FZB42和SQR9的亲缘关系、核心基因以及二次代谢产物合成基因簇。【结果】菌株SF327能够产生生长素吲哚-3-乙酸，是一株有益的根围促生菌；对稻瘟病菌、黄瓜枯萎病菌、辣椒疫霉菌、橡胶树胶孢炭疽菌、尖孢炭疽病菌都具有明显的拮抗作用；也具有防治水稻白叶枯病的生防潜力。菌株SF327基因组全长4.08 Mb，GC含量为46.49%，共编码4 033个基因，含有13个潜在的次生代谢产物编码基因簇，不含有质粒。SF327与FZB42和SQR9具有较近的亲缘关系，有87%以上的核心基因相同，但与SQR9的亲缘关系较近。【结论】B. velezensis SF327是一株具有宽广拮抗谱的多功能菌株，具有较好的生防应用潜力。

Bacillus velezensis SF327, a potential biocontrol agent with the functions of preventing plant diseases and promoting plant growth

[Objective] To screen plant rhizosphere growth-promoting Bacillus velevensis and analyze the biocontrol potential and genome characteristics of the target strain.[Methods]We screened out the growth-promoting strain SF327 through the experiment on pak choi (Brassica campestris sp.chinensis L.) and analysis of plant traits.The activity of strain SF327 against five plant pathogenic fungi and four phytopathogenic bacteria was tested with the filter paper method.Through spray inoculation in paddy fields,the activity of strain SF327 against rice bacterial blight was evaluated.We predicted the secondary metabolites of SF327 using antiSMASH.Moreover,we explored the genetic relationship between SF327 and the plant growth-promoting B.velezensis FZB42 and SQR9,and compared the core genes and secondary metabolite synthesis gene clusters.[Results] The plant growth-promoting SF327 produced auxin indole-3-acetic acid (IAA) and antagonized Magnaporthe oryza,Fusarium oxysporum f.sp.cucumerinum,Phytophthora capsici,Colletotrichum gloeosporioides,and C.acutatum.It had the potential for biocontrol of rice bacterial blight.The genome of SF327 was 4.08 Mb which was composed of a circular chromosome of 4 081 758 base pairs without plasmid and with G+C content of 46.49%,4 033 protein-coding sequences,and 13 gene clusters for secondary metabolites.SF327 strain showed close genetic relationship with strain FZB42 and SQR9,particularly SQR9,and they shared 87% core genes.[Conclusion] B.velezensis SF327 is versatile with a broad antagonistic spectrum,which can be a promising biocontrol agent.