BREEDING PIERCES DISEASE RESISTANT WINEGRAPES

• Author(s): Tenscher, Alan; Walker, Andrew;
• Abstract: Strong and continued progress is being made breeding Pierces disease (PD) resistant winegrapes. We have been able to markedly improve fruit quality while maintaining high levels of PD resistance. At this point we have third generation backcrosses of our 8909-08 (Vitis arizonica/candicans) resistance source onto V. vinifera grapes. This will be the first time that PD resistant selections with so great a percentage (87.5%) of V. vinifera have been produced. We continue to make many crosses, produce thousands of seeds, and plant about 2,000 plants in the field each year. The greenhouse screening system continues to be refined and we have moved to smaller pots and more rapid evaluation to increase the number of seedlings and high fruit quality selections we test. This screening is very severe, but material that passes the screen is reliably resistant and dramatically restricts Xylella fastidiosa (Xf) movement. We are also co-screening for powdery mildew resistance. Strong progress on the development of Xf resistance markers has allowed us to use our PdR1 markers for marker-assisted selection. This years crosses will produce up to 14,000 seeds many with >75% V. vinifera parentage. We have high expectations for strong resistance and excellent wine quality in this and the next generation of seedlings.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium