THE ROLE OF GLASSY-WINGED SHARPSHOOTER SALIVARY ENZYMES IN INFECTION AND MOVEMENT OF XYLELLA FASTIDIOSA

• Author(s): Backus, Elaine; Labavitch, John; Greve, Carl; Shugart, Holly;
• Abstract: The purpose of this project is to determine whether a vectors enzymatic saliva aids the establishment of the few pioneer Xylella fastidiosa (Xf) cells that are inoculated into a plant; thus the bacteria would co-localize with the saliva. Previous work showed that watery saliva of glassy-winged sharpshooter (GWSS) degrades cell walls, and is injected into xylem during feeding. Saliva contains cell wall-degrading enzymes, notably -1,4-glucanase (EGase), which can degrade pit membranes that impede cell-to-cell movement of bacteria. We plan to immunoprobe for salivary EGase, in grape stems fed-upon by GWSS that have acquired green fluorescent protein (GFP)-transformed Xf, to co-localize Xf with both sheath and watery saliva. This year, we: 1) improved protocols for histology of salivary sheaths using epifluroescence light microscopy, 2) dissected 500 pairs of salivary glands to extract EGase and raise antibodies, 3) showed histologically that the salivary sheath dissolves over time, resulting in cellular abnormalities typical of cell-wall loosening, and 4) showed that sheath and watery saliva are directly injected into and travel through xylem cells.
• Publication Date: Nov 2006
• Journal: 2006 Pierce's Disease Research Symposium