|Walker, M. Andrew -|
Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: November 15, 2010
Publication Date: December 10, 2010
Citation: Ramming, D.W., Walker, M., Lin, H. 2010. BREEDING PIERCE’S DISEASE RESISTANT TABLE AND RAISIN GRAPES AND THE DEVELOPMENT OF MARKERS FOR ADDITIONAL SOURCES OF RESISTANCE. CDFA Pierce's Disease Control Program Research Symposium, Dec 15-17, 2010, San Diego, CA. p. 243-248. Interpretive Summary: Although Pierce’s disease (PD) has existed in California since the late 1800s, introduction of the glassy-winged sharpshooter to California significantly increased the PD incidence and damage. A collaborative breeding program was started in 2000 to develop PD resistant table and raisin grapes with high fruit quality comparable to that existing in markets today. Fifth generation (BC4 ) crosses for quality table and raisin grapes with V. arizonica source of PD resistance were made again this year. These families will have high fruit quality as they consist of 97% V. vinifera. An example of increased fruit quality is the selection this year of eleven new raisin grapes made from BC3 V. arizonica families which will be propagated for production trials. Two new BC2 V. arizonica raisin selections were made and will be propagated for production trials. The use of molecular markers has allowed the selection of PD resistant seedlings while they are still in test tubes. Four hundred thirty-six resistant seedlings were selected from 918 seedlings this year, thereby making the breeding program more efficient. Advanced selections are screened in the greenhouse to verify PD resistance. The use of molecular markers and greenhouse screening has made possible the pyramiding of PD with powdery mildew (PM) resistance. Forty-five PD resistant plants were selected by markers from 98 plants and 31 of these were resistant to PM in the greenhouse screen. Over 500 seedlings from BD5-117 family, a source of resistance that is different from V. arizonica, are being evaluated a second time for fruit characteristics to map with resistance. To date, 247 seedlings have been tested in the greenhouse for resistance to PD. A rough molecular map is being made with 65 fluorescent labeled SSR markers. This collaborative research between USDA/ARS, Parlier and University of California, Davis has the unique opportunity to develop high quality PD resistant table and raisin grape cultivars for the California grape industry where PD could restrict the use of conventional table and raisin grape cultivars.
Technical Abstract: The first BC4 V. arizonica crosses made in 2009 resulted in 283 seedlings with molecular markers for PdR1 resistance that were planted in the field. These seedlings will have high fruit quality as they consist of 97% V. vinifera. A total of 918 seedlings from all V. arizonica crosses were screened with molecular markers for PdR1 while still in test tubes from embryo culture and 436 (47%) were resistant. The use of molecular markers to select for PD resistance and greenhouse screening to select for PM resistance allows pyramiding of these two resistance genes and 31 plants with both were planted in the field. In 2010, 28 of 41 crosses attempted were successful and produced 1,600 berries, 2,114 ovules and 293 (13.9%) embryos for PD resistance. An additional 13 crosses to pyramid PD and PM resistance produced 1,782 berries, 2,172 ovules and 341 (15.7%) embryos. Eight seeded crosses made in 2010 produced 415 seed for PD resistance. Evaluation of BC3 fruiting seedlings continued with the selection of eleven new raisin seedlings with PdR1 molecular markers for propagation in production trials. Fruit quality of these selections is similar to the most advanced selections in the raisin breeding program. Over 500 seedlings from the BD5-117 family, with PD resistance different than V. arizonica, are being evaluated for cluster size, berry size and color, and seed/aborted seed size to determine fruit quality. Two hundred forty-seven seedlings of this family have been evaluated in the greenhouse for PD resistance. A rough molecular map is being developed from this population to determine additional molecular markers for PD resistance.