Assessment of transmission, adaptation, and competition of mutant strains of Xylella fastidiosa by glassy-winged sharpshooter (Homalodisca vitripennis)

Authors: Lin, Hong; Sengoda-Gounder, Venkatesan; Shi, Xiangyang; Krugner, Rodrigo; Backus, Elaine

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2018
Publication Date: 12/17/2018
Citation: Lin, H., Sengoda-Gounder, V., Shi, X., Krugner, R., Backus, E.A. 2018. Assessment of transmission, adaptation, and competition of mutant strains of Xylella fastidiosa by glassy-winged sharpshooter (Homalodisca vitripennis). CDFA Pierce's Disease Control Program Research Symposium. p. 138.

Interpretive Summary:

Technical Abstract: Grapevine Pierce’s disease (PD) is caused by Xylella fastidiosa and transmitted by glassy-winged sharpshooters (GWSS), Homalodisca vitripennis. X. fastidiosa is a foregut-borne, xylem-limited and non-flagellated, gram-negative bacterium. This bacterium is propagative and noncirculative in its insect vectors. The putative functions of virulence genes of X. fastidiosa have been characterized by creating deletion mutants and complemented strains via mechanical inoculation of grapevines followed by in- planta pathogenicity assays. However, information regarding functional roles of virulence genes involved in transmission of X. fastidiosa by GWSS is very limited. To further understand their roles involved in transmission by GWSS, several mutant strains including Xf-'rpfA, Xf-'gacA, Xf-'pilG, Xf-'popP and Xf-'pilH were investigated via artificial diet acquisition and subsequent inoculation to grapevines. Thirty plants were inoculated for each mutant and were maintained in greenhouse for symptom development and further analyses. Functional confirmation of key virulence genes responsible for transmission through GWSS will facilitate development of target basis for therapeutic control of grape PD.