The USDA grape rootstock improvement program, based at the Grape Genetics Research Unit, is breeding grape rootstocks resistant to aggressive root-knot nematodes. We define aggressive root-knot nematodes as those which feed on and damage the rootstocks Freedom and Harmony. In 2007 we screened 2669 candidate grape rootstock seedlings for resistance to aggressive rootknot nematodes. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. These selected seedlings are propagated and then planted into the vineyard. In 2007 we planted 70 nematode resistant rootstock selections in the vineyard. These selections were identified in nematode resistance screening in 2006 and 2005. We tested the propagation ability of 105 nematode resistant selections and inoculated the 20 easiest rooting selections with aggressive root-knot nematodes to confirm the resistance of these selections. In 2007 we pollinated 1193 clusters of crosses in 87 unique combinations specifically aimed at the breeding of improved rootstocks with resistance to aggressive root-knot nematodes. An additional 305 clusters in 16 cross combinations were pollinated specifically for genetic study. We identified nematode resistant germplasm that may be parents for rootstock breeding. We sent nine nematode resistant elite selections to Foundation Plant Services (FPS) for virus testing; only virus tested plant material of our rootstocks will be released. Virus testing by FPS anticipates the release of some or all of these selections as rootstocks within several years.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF2007-10-16 11:44:162017-10-16 11:45:10Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes