DIFFERENTIAL PLANT-INDUCIBILITY OF PUTATIVE VIRULENCE GENES BY XYLELLA FASTIDIOSA IN SUSCEPTIBLE AND RESISTANT PLANT HOSTS

• Author(s): Lindow, Steven; Newman, Karyn;
• Abstract: Although many studies have addressed systemic movement of Xylella fastidiosa in the plant (4), we still lack a basic understanding of the mechanism by which X. fastidiosa cells, which initially are inoculated into relatively few xylem vessels, are able to spread throughout the xylem network of the host plant. Furthermore, we lack an understanding of why systemic movement by X. fastidiosa occurs in some host plant species but not in others. In other plant pathogens, including Xanthomonas campestris, which is closely related to X. fastidiosa, the expression of virulence genes such as those encoding gum synthesis, endoglucanase and pectinase activities, is required for systemic movement in planta. The genomic similarities between X. fastidiosa and Xanthomonas strongly suggest that similar virulence genes are required by X. fastidiosa for symptom formation in the plant (2). In some plant pathogens expression of virulence genes is dependent on certain plant factors. In this study we aim to determine the expression pattern of these virulence genes by X. fastidiosa during colonization of grapevines susceptible and resistant to Pierces disease. Reporter genes will be placed under the control of regulatory regions of the genes to be studied, and these promoter-reporter constructs will be integrated into the X. fastidiosa genome to allow their stable expression in planta. Reporter gene expression will be monitored during different phases of disease progress to elucidate when expression of each gene occurs during disease progression. These data will enable us to construct a fairly accurate description of the course of virulence events leading to Pierces disease after infection and to detect plant factors that affect virulence of X. fastidiosa.
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium