Targeting flagellar-mediated virulence: The lipopeptide PW-1 suppresses pathogenicity in Ralstonia solanacearum.

Bacterial wilt caused by Ralstonia solanacearum is a devastating soil-borne disease, calling for novel green control strategies. This study reports that the natural lipopeptide PW-1 controls this disease through an "anti-virulence" mechanism without inhibiting pathogen growth. Phenotypic analysis showed that PW-1 specifically impaired bacterial motility. Transcriptome sequencing revealed that PW-1 coordinately downregulated flagellar biosynthesis-related genes, and transmission electron microscopy confirmed the loss of flagellar filaments in PW-1-treated cells. Using GFP-tagged bacteria, we demonstrated that PW-1 significantly weakened early root colonization and systemic vascular invasion of the pathogen in tobacco. Correlation analysis of 107 field isolates indicated a strong positive relationship between motility and pathogenicity. Furthermore, a flhDC knockout mutant completely lost motility and exhibited drastically reduced virulence, genetically validating the essential role of flagella in pathogenicity. This work identifies PW-1 as a flagellum-targeting inhibitor that attenuates bacterial wilt by disrupting virulence, providing a theoretical basis and a lead compound for developing novel green pesticides targeting flagellar-mediated infection.