Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes

The USDA Agricultural Research Service (USDA-ARS) grape rootstock improvement program in Geneva, NY has gone through some significant personnel and management changes in the past two years as a result of the resignation of Dr. Peter Cousins from his ARS rootstock breeder position and the abolishment of the vacated rootstock breeder position by ARS due to the recent federal budget cuts. However, there are many promising rootstock selections in the current Geneva rootstock breeding pipeline and it is vital to ensure that these selections are maintained and carried through the breeding process. To meet this challenge, a multi-discipline and –institution cooperative research team has been formed under the encouragement and endorsement of the California grape industry. Dr. Matthew Fidelibus of University of California-Kearney Agricultural Research and Extension Center (UC-KARE) will lead the effort for evaluation of horticultural characteristics and graft performance of the rootstock selections generated from the Geneva rootstock breeding program. Dr. Gan-Yuan Zhong of the USDA-ARS Grape Genetics Research Unit (GGRU) in Geneva, NY, on the other hand, will lead the effort for creating rootstock breeding populations and evaluating these populations and advanced selections for root-knot nematode (RKN) resistance and propagation ability. By forming such a team, we can effectively leverage complementary expertise and capabilities from different organizations to meet the overall project objectives in a timely and efficient manner.

The new team has been in operation since summer of 2013. In spite of the transition, we accomplished all the major goals of 2013. We maintained 687 resistant rootstock selections/mothervines at the UC KARE in Parlier, CA. We worked with nursery representatives and identified 30-40 of the selections for further evaluation on the basis of horticultural characteristics. We screened 854 grape rootstock seedlings for resistance to aggressive root-knot nematodes and retained more than 100 candidate selections for further evaluation. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. We tested the propagation ability of 49 selections which are currently planted in KARE (already tested once for nematode resistance). We also screened a population, which also is qualified for consideration as rootstocks, for nematode resistance marker development. We continued the effort in evaluating 22 selections, grafted to Syrah, in replicated rootstock trials at the UC-KARE. Matador, Minotaur, and Kingfisher rootstocks, released by this USDA ARS grape rootstock breeding program in 2010, are being distributed by Foundation Plant Services and planted by California nurseries.