|SHI, XIANGYANG - University Of California|
Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2015
Publication Date: 8/25/2015
Citation: Shi, X., Lin, H. 2015. Characterization of Xylella fastidiosa popP gene required for pathogenicity. Physiological and Molecular Plant Pathology. 89:55-61.
Interpretive Summary: The bacterium Xylella fastidiosa (Xf) causes grape Pierce’s disease of grapes. To reveal the virulence gene responsible for the disease, a mutant was developed by removing the target gene in Xf. Greenhouse inoculation experiments showed that mutant strain lost virulence as compared with wild type Xf, demonstrating that the target gene is responsible for virulence. This study provides new information for understanding mechanisms of pathogenicity in Xf.
Technical Abstract: Xylella fastidiosa (Xf) possesses a two component regulatory system (TCS) popP-popQ which differentially regulates genes in response to environmental stimuli. To elucidate the role of popP in Pierce’s disease (PD) of grapes, a site-directed deletion method and chromosome-based genetic complementation strategy were employed to create the Xf'popP mutant and complementary Xf'popP-C strains. In planta experiment showed that grapevines inoculated with Xf'popP yielded no symptoms, while grapevines inoculated with wild type Xf and Xf'popP-C showed typical PD symptoms. Xf titers in the grapevines inoculated with Xf'popP were significantly lower than that of Xf'popP-C and wild-type. In vitro studies showed that while the mutants and wild types had similar growth curves, Xf'popP showed significant reduction in cell-cell aggregation and cell-matrix adherence. Biofilm production of Xf'popP was 42% less than that of wild type and Xf'popP-C. These results indicate that Xf popP is required for Xf pathogenicity.