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

Abstract:

[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.

Key words:Bacillus velezensis;plant growth-promoting rhizobacteria;biological control;whole-genome analysis