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Heat-stable antifungal factor (HSAF) isolated from Lysobacter enzymogenesis considered a potential biocontrol agent. However, the target of HSAF in phytopathogenic fungi remains unclear. In this study, we investigated the target of HSAF in Valsa pyrithat causes fatal pear Valsa canker. Thirty-one HSAF-binding proteins were captured and identified by surface plasmon resonance (SPR) and high-performance liquid chromatography–mass spectrometry (LC–MS/MS), and 11 deletion mutants were obtained. Among these mutants, only ΔVpVEB1showed decreased sensitivity to HSAF. Additionally, ΔVpVEB1exhibited significantly reduced virulence in V. pyri. Molecular docking and SPR results revealed that HSAF bound to threonine 569 and glycine 570 of VpVeb1, which are crucial for AAA ATPase activity. Another study showed that HSAF could decrease the ATPase activity of VpVeb1, leading to the reduced virulence of V. pyri. Taken together, this study first identified the potential target of HSAF in fungi. These findings will help us better understand the model of action of HSAF to fungi.

Among Lysobacterspecies, Lysobacter antibioticushas been demonstrated to be an interesting source of antimicrobial metabolites for the biocontrol of plant diseases. Although the antibacterial activity was attributed to N-oxide phenazines, the active compounds involved in the antifungal function remained unknown. In this work, an antifungal compound was isolated and identified as p-aminobenzoic acid (pABA). Antifungal activity screening revealed that pABA shows activity against a number of plant pathogens. The genes involved in the synthetic route of this compound in OH13 were identified. Further, the production of pABA was optimized by modification of the carbon source using engineered L. antibioticusOH13 strains.