Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/25/2006
Publication Date: 3/17/2006
Citation: Backus, E.A., Joost, P.H., Shugart, H. 2006. Where, when and how do ingestion and other feeding behaviors of the glassy-winged sharpshooter allow inoculation of Xylella fastidiosa? [abstract]. AgBiotech 2006 A Central California Agricultural Biotechnology Conference. p. 22.
Technical Abstract: Many nagging questions about the mechanisms of transmission of Xylella fastidious (Xf) by glassy-winged sharpshooter (GWSS) exist, hindering development of resistant crops, as well as predictive epidemiological models for ultimate GWSS impact on California crops. Research in the Backus lab aims to answer the remaining questions about the mechanism of transmission, especially inoculation. Using electrical penetration graph (EPG)-monitoring of identified, inoculative, GWSS probes combined with green fluorescent protein (GFP)-transformed Xf, we are tracing the complete process of Xf inoculation, systemic infection and symptom development. GWSS are caged on acquisition plants for 3-8 days. To study acquisition, insects are assayed for presence and location of bacteria using confocal laser scanning microscopy (CLSM). Results show a spatial progression of bacterial colonization in different portions of the GWSS foregut. Bacteria line the precibarium by day 3, but do not colonize the more distant cibarium until day 6. To study inoculation, a wired GWSS that has acquired GFP-Xf is EPG-monitored while probing transparent artificial diet. Views of its stylets and salivary sheath are simultaneously video-captured and synchronized with EPG waveforms. Preliminary results show that GFP-Xf is present and visually resolvable following injection by the stylets into artificial diet. Green glow from GFP bacteria was visible both in the diet and within the salivary sheath. However, synchronization between video and EPG recording of behavior was not perfect in these earliest tests. Tests are being repeated at present to determine the EPG waveform correlated with inoculation.