Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2009
Publication Date: 8/1/2009
Citation: Lin, H., Cheng, D.W., Felix, F.B., Walker, A.M. 2009. Identification of Grapevine Xylem Sap Protein Profiles in Response to Xylella fastidiosa Infection. Phytopathology(99):S74. Interpretive Summary:
Technical Abstract: Pierce’s Disease (PD) of grapevines is caused by the Gram-negative, xylem-limited bacterium Xylella fastidiosa (Xf). All Vitis vinifera-based cultivars are highly susceptible to Xf infection. However, some grape species from the southern United States (such as V. arizonica, V. Shuttleworthii, V. simpsonii, V. smalliana and Muscadinia rotundifolia) are resistant. Given that Xf is limited to xylem vessels, it has been speculated that chemical composition of host xylem sap could play an important role in Xf pathogenesis. Xylem sap contains organic acids, sugars, amino acids, phytohormones and proteins. Our in vitro studies demonstrated that culture media amended with xylem sap collected from PD-susceptible grapevines provided better support for bacterial growth and biofilm formation than media supplemented with xylem sap from PD-resistant grapevines. To further investigate underlying molecular profiles and dissect possible molecular mechanisms involved, we identified protein profiles of xylem sap collected from PD resistant- and susceptible-genotypes segregating from V. arizonica X V. rupestri breeding population. We have identified proteins involved cell wall metabolism such as cell wall degradation, lignification and cell death. We also identified pathogenesis-related proteins such as "thaumatin-like protein” (TLP), a protein reported to confer defense response to microbial infection. The identification of sap proteins involving phosphorylation modifications suggest possible roles in regulation of development, and/or response to biotic/abiotic stresses.