BIOLOGICAL, CULTURAL, GENETIC, AND CHEMICAL CONTROL OF PIERCES DISEASE: PRODUCTION AND SCREENING OF XYLELLA FASTIDIOSA TRANSPOSON PATHOGENICITY AND ATTACHMENT MUTANTS

• Author(s): Guilhabert, Bruce; Purcell, Alexander; Walker, Andrew;
• Abstract: One of our projects involved the development of a transformation and transposon mutagenesis systems for the bacterium that causes Pierce's disease (PD), Xylella fastidiosa (Xf). We now have a random transposon mutagenesis system working for Xf (Guilhabert, et al. 2001) and recently we have developed an E. coli/Xf plasmid shuttle vector. We are currently assessing the stability of the E.coli/Xf plasmid shuttle vector in Xf without antibiotic selection. The results of these experiments will let us know whether this plasmid will be stably maintained in Xf cells that are inoculated in plants, something that will be essential for evaluating genes in planta. Understanding the complex interactions between the plant, pathogen, and insect vector is imperative for the development of effective disease controls. Recently, the complete genome sequence of a citrus strain of Xf was determined (Simpson et al., 2000) and the complete sequence of a grape-infecting Xf strain (Temecula) is nearly complete. Earlier analysis of the CVC genome revealed important information on potential plant pathogenicity and insect transmission genes. However, more than half (53%) of the identified ORFs in Xf CVC encode proteins with no assignable function. In addition, some of the putative gene functions assigned on the basis of sequence homology with other prokaryotes may be incorrect. In order to identify and understand the function of Xf genes, it is imperative to develop techniques to knock out and complement putative pathogenicity or transmission genes.
• Publication Date: Dec 2002
• Journal: 2002 Pierce's Disease Research Symposium