Analysis of grapevine xylem sap for evidence of host cell wall degrading enzymes associated with colonization by Xylella fastidiosa

• Author(s): Greve, Carl; Kirkpatrick, Bruce; Labavitch, John; Roper, M.;
• Abstract: Xylella fastidiosa, the causal agent of Pierces disease, poses a major threat to the California grape industry. Infected vines often have occluded vessels in the xylem. The exact origin of these occlusions is unknown as is the mechanism by which X. fastidiosa is able to breach the pit membranes that separate xylem vessels from one another. It is likely that this bacterium utilizes cell wall degrading enzymes to facilitate systemic movement. GC analysis was used to determine the nature of this cell wall breakdown. The data show an increase in pectin breakdown products in xylem sap from infected vines relative to healthy indicating that pectin digestion may be a means by which the bacteria spread. Direct enzyme activity has thus far been difficult to detect but immunodetection techniques to test for the presence of cellulases and polygalcturonases are under development. These enzymes are apparently encoded by ORFs in the X. fastidiosa genome.
• Publication Date: Jun 2002
• Journal: Phytopathology