Abstract

Traditional control methods have drawbacks in controlling Verticillium wilt diseases caused byVerticillium dahliaeKleb.; therefore, an efficient and environmentally friendly strategy for disease control must be identified and the mechanisms determined. In this study, a soil-isolated strain SBB was identified asBacillus velezensisbased on 16S rRNA,gyrA, andgyrBgene sequences. In vitro, strain SBB had excellent inhibitory effects onV. dahliae, with the highest inhibition rate of 70.94%. Moreover, strain SBB inhibited production of the conidia ofV. dahliaeand suppressed the production of microsclerotia and melanin. Through gas chromatograph–mass spectrometer analysis, nine compounds were detected from the volatile organic compounds produced by SBB, among which 2-nonanol, 2-heptanone, 6-methyl-2-heptanone, and 2-nonanone could completely inhibitV. dahliaegrowth. Strain SBB produced cellulase, amylase, protease, and siderophore. During inhibitory action onV. dahliae, strain SBB showed upregulated expression of genes encoding non-volatile inhibitory metabolites, including difficidin, bacilysin, and bacillaene, at 1.923-, 1.848-, and 1.448-fold higher, respectively. Thus, our study proved that strain SBB had an efficient antagonistic effect onV. dahliae, suggesting strain SBB can be used as a potential biological control agent against Verticillium wilt.Keywords:Verticillium dahliae;Bacillus velezensis;biological control;antagonistic effect