The LysR-Type Transcriptional Regulator CrgA Negatively Regulates the Flagellar Master Regulator <i>flhDC</i> in Ralstonia solanacearum GMI1000
Xiaojing Fan, Zhiwen Zhao, Tingyan Sun, Wei Rou, Caiying Gui, Tahira Saleem, Xuxu Zhao, Xianyuan Xu, Tao Zhuo, Xun Hu, Huasong Zou
Abstract
Ralstonia solanacearum is a widely distributed soilborne plant pathogen that causes bacterial wilt disease on diverse plant species. Motility is a critical virulence attribute of R. solanacearum because it allows this pathogen to efficiently invade and colonize host plants. In R. solanacearum , motility-defective strains are markedly affected in pathogenicity, which is coregulated with multiple virulence factors. In this study, we identified a new LysR-type transcriptional regulator (LTTR), CrgA, that negatively regulates motility. The mutation of the corresponding gene leads to the precocious appearance of wilt symptoms on tomato plants when the pathogen is introduced using soil-soaking inoculation. This study indicates that the regulation of R. solanacearum motility is more complex than previously thought and enhances our understanding of flagellum regulation in R. solanacearum .