BIOLOGICAL CONTROL OF PIERCES DISEASE WITH NON-PATHOGENIC STRAINS OF XYLELLA FASTIDIOSA

• Author(s): Cooksey, Donald;
• Abstract: This project is to construct and test nonpathogenic strains of X. fastidiosa derived from a pathogenic Pierces disease strain for competitive exclusion of the pathogen in grapevines. Potential virulence genes were selected from comparative genome sequence analyses as well as DNA macroarray studies of differential gene expression. A more comprehensive analysis of differential gene expression with a DNA microarray approach is an outcome of this project and is funded under a new grant. Disruption of xanthan gum production by mutations in gumD and gumH resulted in less of a slime layer and fewer adhering cells than the wild-type strain on plastic and wood surfaces. However, when biofilm formation was quantitatively measured in polystyrene microtiter plates, both gumD and gumH mutants formed significantly more biofilm than the wild-type X. fastidiosa. In addition, the disruption of rsmA resulted in significantly more biofilm that the parent strain. Virulence assays in grapevine are still in progress, but gum mutants showed fewer symptoms than the parent strain in an alternative host assay. The analysis of potential virulence genes has also had side benefits for epidemiological work on Xylella by providing new primer sets for differentiate certain host strains of X. fastidiosa.
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium