Identification of the biological control bacterium XNB-02 and its action mechanism in prevention of the tobacco brown spot
In order to obtain the biocontrol bacterial strains with excellent effect on the prevention and control of tobacco brown spot disease,bacterial strains were isolated and purified from soil samples in Xining City,Qinghai Province.Bacterial strains with good inhibitory effects on tobacco brown spot dis-ease were screened,and their inhibitory effects on six other plant pathogens were determined.The mor-phological,physiological and biochemical characteristics were analyzed using molecular biological technology to identify the screened strains.The inhibitory mechanism was preliminarily investigated,and the greenhouse pot plant disease prevention test was performed and biocontrol efficacy of this strain on tobacco brown spot was tested.The stability of the fermentation broth of the strain,the biocontrol-related genes in the strain,and the effect of the strain on the disease resistance genes in tobacco were in-vestigated.The results showed that five strains were obtained after isolation and purification,among which the biocontrol strain XNB-02 had a good inhibitory effect on Alternaria alternata with a radius of inhibition of 10.33 mm,and also had a good inhibitory effect on six other plant pathogens.The strain XNB-02 was identified as Bacillus velezensis.The strain XNB-02 could promote the growth of tobacco seedlings,and the prevention effect of XNB-02 against tobacco can reach 61.82％when the concentra-tion of its suspension was 1×109 CFU/mL.The intracellular crude extract of the biocontrol strain XNB-02 could inhibit the growth of mycelium and spore germination of A.alternata,and change the morphol-ogy of mycelium and spores.The inhibitory effect of the biocontainment strain XNB-02 on A.alternata did not change significantly after treatment at temperatures lower than 90 ℃,pH 3-13,light exposure for seven days,UV irradiation for 240 min and proteinase K.Disease resistance genes were activated in tobacco after inoculation with the biocontrol strain XNB-02.The genes related to biosynthesis of lipo-peptide antibacterial substances such as surface activein,ichthyobacillus and fenugreek were present in the biocontrol strain XNB-02.These results suggest that the biocontrol strain XNB-02 has the potential to be developed as a biocontrol agent against tobacco brown spot.
Bacillus velezensistobacco brown spotantifungal substanceextractstabilitydisease-resistance genebiocontrol-related gene
万方数据
维普
