• Bacillus velezensis HSX-1 was isolated from healthy chrysanthemum plants. • HSX-1 inhibits Fusarium oxysporum and controls chrysanthemum wilt. • HSX-1 disrupts membrane integrity and ROS homeostasis of F. oxysporum. • HSX-1 produces IAA and siderophores. • HSX-1 promotes Chrysanthemum morifolium growth. Chrysanthemum wilt caused by Fusarium oxysporum is a devastating disease that causes substantial economic losses. Biological control agents are considered an effective approach to control plant diseases. In the present study, the biocontrol efficacy and mechanisms of the newly isolated Bacillus velezensis strain HSX-1 against F. oxysporum were evaluated. B. velezensis HSX-1 significantly suppressed the mycelial growth of F. oxysporum by 65.52% in the dual culture test. In addition, a 15% concentration of the cell-free supernatant (CFS) from B. velezensis HSX-1 significantly suppressed colony radial growth as well as spore germination of F. oxysporum . Whole-genome sequencing identified gene clusters responsible for biocontrol activity, including those encoding nonribosomal peptides, polyketide antibiotics, siderophores, and extracellular hydrolases. B. velezensis HSX-1 has the ability to effectively reduce the virulence of F. oxysporum and promoted the growth of Chrysanthemum morifolium . Strain HSX-1 produces multiple plant growth-promoting metabolites, including indole-3-acetic acid (IAA) and siderophores. Phenotypic and transcriptome analyses revealed that strain HSX-1 inhibits F. oxysporum by disrupting the cell membrane integrity and reactive oxygen species (ROS) scavenging system. All of these results indicated that B. velezensis HSX-1 has strong potential to be developed as a biocontrol agent to control Chrysanthemum wilt caused by F. oxysporum and promote C. morifolium growth.
Wang et al. (Sun,) studied this question.