Bioactivities Of The Volatile Organic Compounds Of Bacillus Velezensis Canl-30 And Formulation Of A Wettable Powder

Bacillus species are important microorganisms in soil,plant rhizosphereand surfaces.It has the ability to produce a variety of antibacterial compounds,and the secondary metabolites produced have certain biological activities,such as bacteriostatic,insecticidal,enhancing plant resistance against biotic or abiotic stresses and promoting plant growth.In this study,the strain Can L-30 of Bacillus sp.as the research object to clarify its classification status,to determine the biological activity of the volatile organic compounds?VOCs?,and to prepare a wettable powder based on endospores of strain Can L-30.Finally,its effects on controlling Leptosphaeria biglobosa and Sclerotinia sclerotiorum on oilseed rape,and on yield of oilseed rape were measured.The main findings were summarized below:1. The taxonomic status of Bacillus sp.Can L-30 was clarified.The results showed that Can L-30 belongs to B.velezensis.2. Strain Can L-30 was found to be rich in production of secondary metabolites based on its genome information. Through antismash online comparison,12 secondary metabolites were found.Among them,the gene clusters that synthesize antibiotics macrolactin,difficidin,fengycin,bacillaene active substances were found.3. Proved that the volatile gas produced by B. velezensis Can L-30 can promote plant growth and induce plant disease resistance.It was confirmed that Can L-30VOCs can significantly promote the growth of Arabidopsis thaliana and rapeseed plants,and significantly enhance the resistance of Arabidopsis to Botrytis cinerea infection.37 kinds of gases were produced by B.velezensis Can L-30.Among them,the VOCs that increased plant ISR were undecaneand 2-dodecane.VOCs with plant growth promotion are 2-heptanone,2-nonanone.Through the analysis of A.thaliana transcriptome data enrichment pathways and verification of differentially expressed genes.The above results showed that the VOCs of B.velezensis Can L-30 regulate both plant growth and resistance mediated by multiple hormone-responsive pathways.4. A wettable powder with a concentration of 1×10¹¹cfu/g was prepared from B. velezensis Can L-30,and the biological activity was evaluated and field tests were performed.In the laboratory test?Cylinder-plate method?,the wettable powder had a significant antibacterial effect on Lb,the average diameter of the bacteriostatic circle was 3.1 cm.In vivo test,the wettable powder significantly inhibited the expansion of the above two pathogens on rape,and the average diameter of the inhibition zone was0.86 cm and 2.6 cm,respectively.The high temperature stability test of Can L-30 wettable powder is 83.33%,the suspending rate is 98.22%,the wetting time is 105s,and the viable bacteria amount for 9 months storage at room temperature is 1.33×10¹¹cfu/g,which meets the national pesticide quality standards.5. In Tianmen City and Chibi City,Hubei Province,field trials were conducted to verify the effectiveness of Can L-30 wettable powders in preventing rape S. sclerotiorum and blackleg disease,as well as increasing the yield of rapeseed.The results showed that the biocontrol preparation of Can L-30 had effective biocontrol effects both on sclerotinia stem rot and on blackleg,and had a significant yield-promoting effects on oilseed rape.The results of the Tianmen test field showed that the Can L-30 powder had control efficacies by 58.10%and 50.8%against sclerotinia stem rot and blackleg,respectively,and increased the seed yiled of oilseed rape by 14.4%on average,compared to the control treatment.There were no significant differences between the treatments of the Can L-30 powder and prochloraz in all the observed parameters.The results of the Chibi test field showed that the Can L-30 powder had the efficacies in control of sclerotinia stem rot and blackleg by51.5%and 33.1%,respectively,and increased the seed yield of oilseed rape by 11.8%.There were also significant differences between the treatments of the Can L-30powder and prochloraz in all the observed parameters.