CONTROL OF PIERCES DISEASE THROUGH DEGRADATION OF XANTHAN GUM

• Author(s): Cooksey, Donald; Schiller, Neal;
• Abstract: Pierces disease of grapevine and other leaf scorch diseases caused by Xylella fastidiosa are associated with aggregation of the bacteria in xylem vessels, formation of a gummy matrix, and subsequent blockage of water uptake. In the closely related pathogen, Xanthomonas campestris, xanthan gum is known to be an important virulence factor, probably contributing to bacterial adhesion, aggregation, and plugging of xylem. The recently published genome sequence of the citrus strain of X. fastidiosa revealed that this pathogen also has genes for xanthan gum production. This project is to identify bacteria that produce xanthan-degrading enzymes to target this specific virulence factor of X. fastidiosa. This approach has the potential to significantly reduce damage caused by Pierces disease in grapes and potentially in other hosts of X. fastidiosa, such as almonds and oleander. If xanthan gum is important in the aggregation of the pathogen in the insect vector, then our approach may also reduce the efficiency of transmission of Pierces disease. Our first approach will be to develop endophytic bacteria that produce these enzymes in the xylem of grapevines, but another approach is to engineer grape plants to produce these enzymes. Through the cloning and characterization of genes encoding xanthases and xanthan lyases, we will facilitate possible efforts to transform grapevines to produce these enzymes.
• Publication Date: Dec 2002
• Journal: 2002 Pierce's Disease Research Symposium