Location: Crop Diseases, Pests and Genetics
2011 Annual Report
This research contributes to development and evaluation of grape seedling populations and advanced selections to improve table and raisin grape germplasm with resistance to Pierce’s disease (PD).
PD-resistant table and raisin grape varieties are needed to overcome increased incidence of PD as a result of introduction of the glassy-winged sharpshooter. Fruit quality of resistant varieties needs to be equivalent to varieties currently grown for commercial acceptance. Additional backcross generations to combine high quality table and raisin grapes with PD resistance is continuing. This year the first backcross 5 (BC5) crosses using V. arizonica resistance (98.5% V. vinifera) were made. An example of increased fruit quality is this year’s selection of three natural dry-on-the-vine (DOV) and seven tray dry raisin selections, and four table grape selections made from BC3 V. arizonica x V. vinifera families. They were propagated into first stage production trials. Thirty-two seedless x seedless crosses to develop BC3, BC4 and BC5 V. arizonica x V. vinifera families were made. The crosses consisted of 61,244 emasculations. Powdery mildew resistance was combined with PD resistance in 20 additional crosses of 40,025 emasculations. Two table and five raisin grapes were selected from 31 resistant plants and propagated in first stage production trials. Molecular markers were used to detect PD-resistant individuals at the young seedling stage in test tubes. PD resistance of over 185 parents and selections has been verified in greenhouse tests to insure resistance continues to co-segregate with markers. Two hundred and seven seedlings of the BD5-117 mapping family, with PD resistance different than V. arizonica, have been greenhouse tested. A rough molecular map is being developed based on 70 simple sequence primers (SSR) primers and 155 seedlings to develop additional molecular markers for PD resistance.