Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2006
Publication Date: 7/29/2006
Citation: Backus, E.A., Chen, J. 2006. Acquisition of Xylella fastidiosa by glassy-winged sharpshooter: Imaging of bacterial colonies and their locations within the foregut over time. [abstract] Phytopathology 96:S7.
Technical Abstract: The introduction of the glassy-winged sharpshooter (GWSS), Homalodisca coagulata, into southern California has caused a significant increase in incidence of Pierce's Disease in many grape-growing regions. Although host plant resistance to the causative bacterium, Xylella fastidiosa, and/or its GWSS vector is being sought, research is hampered by lack of detailed knowledge of the transmission (acquisition + inoculation) process. X. fastidiosa (Xf) is known to be transmitted in a persistent, non-circulative, cuticula-borne manner. Bacteria colonize the anterior foregut of the vector (the precibarium and cibarium) and are somehow inoculated back into the plant from this area, during the feeding process. As part of our studies of the mechanism of inoculation, we developed confocal and scanning electron microscopy methods to visualize green fluorescent protein (GFP)-expressing Xf in situ within the foregut of the vector. We describe here the first time course study of GFP-Xf acquisition by GWSS, across varying acquisition access periods of 1-7 days. Results show that bacterial colonies first form in the precibarium, especially in the epipharyngeal basin and near the precibarial valve. Bacteria later accumulate in the cibarium. Implications for inoculation of bacteria from these sites are discussed.