1a. Objectives (from AD-416)
Develop Pierce’s disease (PD) resistant table and raisin grape germplasm/cultivars with fruit quality equivalent to standards of present day cultivars. Develop molecular markers for Xf/PD resistance in a family from southeastern United States (SEUS).
1b. Approach (from AD-416)
1) Backcross BC1, BC2, BC3 hybrids (F8909-08 V. arizonica source of resistance) that have been selected for Pierce’s Disease (PD) resistance to high quality V. vinifera seedless table and raisin grapes. 2) Backcross F1 and BC1 resistant bunch grapes from native SEUS source of PD resistance as identified by greenhouse tests with high quality V. vinifera seedless table and raisin grapes. 3) Use embryo rescue to facilitate the hybridization of seedless parents. 4) Use molecular markers to select resistant F8909-08 backcross seedlings. 5) Select seedlings with highest fruit quality and test in the greenhouse to determine resistance. 6) Field test best resistant selections for PD resistance under natural conditions. 7) Perform production and quality trials of selections that have commercial potential. 8) Develop rough framework map of V. vinifera table grape X BD5-117 family to locate PD resistant QTL and develop molecular markers for marker assisted selection. Documents Trust with the Consolidated Central Valley Table Grape Pest and Disease Control District. Log 35507.
3. Progress Report
The goal of this project is to investiage methods of developing Vitis (table and raisin grape) scion germplasm with resistance to Xf infection and/or Pierce's disease (PD) disease development which contributes directly to Objective 3.A. of the in-house project. This funding and research contributes to development and evaluation of grape seedling populations and advanced selections with the goal of improving table and raisin grape germplasm with resistance to PD. The project is also developing new molecular markers based on a family from a complex background of PD resistance. PD-resistant table and raisin grape varieties are needed to overcome increased incidence of PD as a result of the introduction of glassy-winged sharpshooter. Fruit quality of resistant varieties needs to be equivalent to varieties currently grown to be commercially acceptable. Progress in making additional backcross generations to combine high quality table and raisin grapes with PD resistance is continuing. An example of increased fruit quality is this year’s selection of five raisin grapes made from BC3 V. arizonica x V. vinifera families which were propagated into production trials. An additional fifteen BC2 V. arizonica x V. vinifera raisin selections were propagated into production trials. Thirty-nine seedless x seedless crosses to develop additional BC3 and BC4 V. arizonica x V. vinifera families were made. The crosses required 69,884 emasculations. Powdery mildew resistance was combined with PD resistance in 18 additional crosses of 40,122 emasculations. Molecular markers were used to detect Pierce's Disease resistant individuals at the young seedling stage in test tubes for one BC2, nine BC3 and 19 BC4 families from crosses made in 2009. A total of 392 of 910 seedlings were rated resistant and planted in the field. Greenhouse screening for Pierce's Disease resistance was continued to verify that plants with PD resistance markers are indeed resistant.