TrpR-Like Protein PXO_00831, Regulated by the Sigma Factor RpoD, Is Involved in Motility, Oxidative Stress Tolerance, and Virulence in pv. .

pv. () is a Gram-negative bacterium that causes bacterial leaf blight in rice. In this study, we identified a putative TrpR-like protein, PXO_TrpR (PXO_00831), in . This protein contains a tryptophan (Trp) repressor domain and is highly conserved in . Auxotrophic assays and RT-qPCR confirmed that PXO_TrpR acts as a Trp repressor, negatively regulating the expression of Trp biosynthesis genes. Pathogenicity tests showed that knockout in significantly reduced lesion development and disease symptoms in the leaves of susceptible rice. RNA-seq analysis and phenotypic tests revealed that the mutant exhibited impaired cell motility and was more sensitive to HO oxidative stress than the wild-type strain. Furthermore, we found that the sigma 70 factor RpoD controlled the transcription of by directly binding to its promoter region. This study demonstrates the biological function and transcriptional mechanism of PXO_TrpR as a Trp repressor in and evaluates its novel pathogenic roles by regulating flagellar motility and the oxidative stress response.