<i>VirB11</i> , a traffic ATPase, mediated flagella assembly and type IV pilus morphogenesis to control the motility and virulence of <i>Xanthomonas albilineans</i>

Xanthomonas albilineans (Xal) is a gram-negative bacterial pathogen responsible for developing sugarcane leaf scald disease, which engenders significant economic losses within the sugarcane industry. In the current study, homologous recombination exchange was carried out to induce mutations within the virB/D4-like type IV secretion system (T4SS) genes of Xal. The results revealed that the virB11-deletion mutant (ΔvirB11) exhibited a loss in swimming and twitching motility. Application of transmission electron microscopy analysis further demonstrated that the ΔvirB11 failed to develop flagella formation and type IV pilus morphology and exhibited reduced swarming behaviour and virulence. However, these alterations had no discernible impact on bacterial growth. Comparative transcriptome analysis between the wild-type Xal JG43 and the deletion-mutant ΔvirB11 revealed 123 differentially expressed genes (DEGs), of which 28 and 10 DEGs were notably associated with flagellar assembly and chemotaxis, respectively. In light of these findings, we postulate that virB11 plays an indispensable role in regulating the processes related to motility and chemotaxis in Xal.