BIOLOGICAL, CULTURAL, GENETIC, AND CHEMICAL CONTROL OF PIERCE’S DISEASE: PRODUCTION AND SCREENING OF XYLELLA FASTIDIOSA TRANSPOSON PATHOGENICITY AND ATTACHMENT MUTANTS Project Leaders:

INTRODUCTION 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.