The role of xanthan gum-associated genes in the pathogenicity and virulence of Xylella fastidiosa and potential strategies for biological control of citrus CVC

Resumo

The aim of the present research proposal is to investigate the role of xantham gum produced by Xylella fastidiosa in the pathogenicity and virulence of this bacterium in citrus plants, thus fulfilling the major requirement set by FAPESP for projects in this program. In a more direct approach, disruption of genes involved in xantham gum production will be attempted. First, a gene transfer system for X.fastidiosa will be developed and used as the primary tool for gene disruption. The establishment of such a system would be a major contribution to gene function studies that should follow the genome sequencing project. A second approach will involve the exposure of X.fastidiosa to an in planta xantham gum-degrading environment. Endophytes transformed to produce extracellular xantham gum-degrading enzymes into the xylem milieu will be used and their effect on X.fastidiosa infection will be assessed. This indirect approach will circumvent possible limitations of the first approach such as difficulties involved in vitro cultivation of X.fastidiosa and the possibility of incomplete knockout of genes. In addition, this in planta approach could be used as a framework for the development of strategies for disease control. (AU)