Breeding Rootstocks Resistant to Aggressive Root-Knot Nematodes
Grape Genetics Research
2012 Annual Report
1a.Objectives (from AD-416):
To breed, evaluate, and introduce rootstocks that are resistant to aggressive root-knot nematodes, resulting in improved varieties with adaptation to California viticulture. To achieve this objective, we will evaluate the root-knot nematode resistance of 4,000 grape rootstock seedlings and select resistant seedlings for advancement to the field, evaluate the rooting ability of 150 rootstock selections and confirm nematode resistance of easily rooted selections, and enter 11 easily rooted nematode resistance confirmed selections into a replicated rootstock trial.
1b.Approach (from AD-416):
The proposed work is breeding grapevine rootstocks resistant to aggressive virulent root-knot nematode (Meloidogyne species) populations. Grapevine rootstock germplasm will be screened for resistance to aggressive virulent root-knot nematodes, crosses made, and resistant seedling selections identified through screening. Resistant seedlings will be tested for propagation ability and nematode resistance confirmed through replicated plant testing.
Screened more than 2000 candidate grape rootstock seedlings for resistance to aggressive root-knot nematodes. We select only those seedlings which completely suppress nematode reproduction and show zero nematode egg masses. Selected seedlings are propagated and then planted into the vineyard. We propagated more than 100 elite nematode resistant selections and cultivated them in a vineyard nursery block. We tested the propagation ability of more than 90 selections (already tested once for nematode resistance). Cuttings produced callus, roots, or shoots in combination (or none of these). We evaluated 22 root-knot nematode resistant grafted selections for their effect on scions, with pruning weight and fruit weight collected from 11 grafted rootstock selections. Applied a technique to evaluate nematode resistance on rooted grapevine leaves to evaluate the nematode resistance of a mapping population that segregates for nematode resistance.