1a.Objectives (from AD-416)
1. Identification of PD resistance genes in Vitis species.
2. Molecular determination PD resistance mechanisms.
1b.Approach (from AD-416)
1. Identify candidate R genes from microarray global gene expression analyses.
2. Cloning and molecular characterization of target genes using in vitro expression system.
3. Develop R gene molecular markers for marker-assisted selection.
This research project is to identify Pierce's Disease (PD) resistance mechanisms of grapevines in support of Objective 2 of the parent project to determine the nature and mechanism(s) of susceptibility/resistance to Xylella fastidiosa (Xf) infection in Vitis and Prunus species. Comparative proteomic profile analyses of PD-resistant and PD-susceptible grapevines in response to Xf infection were conducted. Total proteins were isolated from stem tissue of Xf-infected and healthy grapevines at 1, 6, and 12 weeks post-inoculation. Proteins were separated by a two dimension polyacrylamide gel system. Differentially expressed proteins in response to Xf infection were isolated and identified using liquid chromatography-mass spectrometry. Ten proteins associated with plant host defense responses to Xf infection were tentatively identified. Genes encoding two defense response proteins, jasmonic acid methyltransferase and methyljasmonate esterase were cloned and characterized. Cooperating researchers cooperatively planned and conducted the research, and communicated regularly via site visits, meeting presentations and research discussions through email and telephone on a weekly basis.