Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/20/2013
Publication Date: 2/21/2013
Citation: Roper, C., Daugherty, M., Perring, T., Backus, E.A. 2013. Characterization of Xylella fastidiosa lipopolysaccharide and its role in key steps of the disease cycle in grapevine. p. 74 In: Pierce's Disease Research Progress Reports, California Department of Food and Agriculture. 262 pp. Interpretive Summary: Pierce’s disease of grape is a lethal condition caused by the bacterium Xylella fastidiosa (Xf). This research focuses on the role of a component of the Xf cell surface, lipopolysaccharide (LPS), in the interaction between bacteria and host plants such as grape, almond, and oleander. LPS is thought to be a key factor that allows Xf to cause disease, because it may mediate attachment to host plant cell walls and formation of bacterial colonies by attraction to other bacterial cells. If LPS is proved to be critical for Xf infection, antimicrobial compounds could be sought that disrupt LPS synthesis to control disease caused by Xf.
Technical Abstract: Xylella fastidiosa (Xf) is the causal agent of Pierce’s Disease of grapevine (PD), and also colonizes and causes disease in other crops such as almond, citrus, and oleander. While all identified Xf isolates belong to the same species, some isolates can cause disease in one host, but not another. This project aims to elucidate molecular mechanisms of Xf interaction with grapevine, almond, or oleander host plants, including bacterial traits that could dictate such host specificity. Focus is on the lipopolysaccharide (LPS) component of the outer membrane, which consists of lipid A, core oligosaccharides, and a variable O-antigen moiety. In particular, O-antigen has been implicated as a virulence factor in several, non-Xf bacterial species. Therefore, it is hypothesized that O-antigen also is involved in virulence of Xf on grapevine via surface attachment and cell-cell aggregation. The latter are two important steps in biofilm formation, a trait necessary for successful colonization of host xylem. Thus far, findings demonstrated that a region of the LPS molecule is essential for Xf interaction with plants. Antimicrobial compounds that disrupt LPS biosynthesis are known and increase bacterial susceptibility to other stresses. Potentially, these compounds could be used alone or in combination with other anti-Xf compounds to control disease.