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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #201209
Title: THE ROLE OF GLASSY-WINGED SHARPSHOOTER SALIVARY ENZYMES IN INFECTION AND MOVEMENT OF X. FASTIDIOSA

Author
item Backus, Elaine
item LABAVITCH, JOHN - UC, DAVIS

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/12/2006
Publication Date: 11/27/2006
Citation: Backus, E.A., Labavitch, J.M. 2006. The role of glassy-winged sharpshooter salivary enzymes in infection and movement of X. Fastidiosa [abstract]. CDFA Pierce's Disease Control Program Research Symposium Proceedings. p. 256.

Interpretive Summary: The purpose of this project is to determine whether the saliva of the glassy-winged sharpshooter (GWSS) aids the establishment of Xylella fastidiosa (Xf) cells that are injected into a plant during GWSS feeding. If so, the bacteria would be located near or in the saliva. Previous work showed that saliva of GWSS degrades cell walls, and is injected into xylem during feeding. Saliva contains cell wall-degrading enzymes which can degrade pit membranes that impede spread of the bacteria throughout the plant. We plan to use antibody-linked probes for salivary enzymes in grape stems fed-upon by GWSS that have previously acquired green fluorescent protein (GFP)-transformed Xf. We will use microscopy to identify locations of Xf and 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 enzyme and raise antibodies, and 3) showed that the salivary sheath dissolves over time, resulting in plant cell disruptions typical of those caused by cell wall-degrading enzymes.

Technical Abstract: The purpose of this project is to determine whether a vector’s 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.