Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/20/2013
Publication Date: 12/6/2013
Citation: Roper, C., Cantu, D., Perring, T., Backus, E.A. 2013. Characterization of Xylella fastidiosa lipopolysaccharide and its role in key steps of the disease cycle in grapevine. Proceedings of the CDFA Pierce's Disease Control Program Research Symposium. p. 74-83. Interpretive Summary: Xylella fastidiosa (Xf) is a bacterium capable of colonizing many different plant hosts. Xf is the causal agent of Pierce’s disease (PD) of grapevine, which has caused major losses for the California grape industry. Presently, PD is controlled by expensive and environmentally disruptive insecticide treatments against the insect carrier (vector) of Xf. A target for genetic control of the bacterium, via host plant resistance, is needed. This research is focused on identifying a new target for genetic control: the role of the Xf cell surface component, lipopolysaccharide (LPS), in pathogenic interactions between Xf and grapevine, almond, and oleander hosts. LPS affects the ability of Xf to attach to host cell walls. This project investigates the contribution of LPS in Xf colonization of host plants and insect vectors. Certain components of the LPS molecule are essential for Xf interaction with plant hosts. Thus, LPS is a logical target for disease control. Antimicrobial compounds that disrupt or retard LPS biosynthesis could make bacteria more susceptible to other stresses. Potentially, these compounds could be used alone or in combination with other anti-Xf compounds to control Pierce's disease.
Technical Abstract: This project aims to elucidate molecular mechanisms of Xylella fastidiosa (Xf) pathogenicity. Work is focused on the lipopolysaccharide (LPS) component of the outer membrane, which consists of lipid A, core oligosaccharides, and a variable O-antigen moiety. Specifically, the O-antigen portion of LPS is targeted for study because it has been implicated as a virulence factor in several other bacterial species. The hypothesis that O-antigen is involved in virulence of Xf on grapevine is being evaluated. Moreover, function of LPS in surface attachment and cell-cell aggregation is being investigated; these are two important steps in biofilm formation, a trait necessary for successful colonization of host xylem. This study will also determine the role that LPS plays in insect transmission (acquisition and inoculation).