ISHS Acta Horticulturae 623: XXVI International Horticultural Congress: Plant Genetic Resources, The Fabric of Horticulture's Future
EVALUATION OF VITIS AESTIVALIS AND RELATED TAXA AS SOURCES OF RESISTANCE TO ROOT-KNOT NEMATODES |
| Authors: | L.E. Boyden, P. Cousins |
| Keywords: | Meloidogyne, grape, breeding, rootstock, genetics |
| Abstract:
Development of rootstocks with resistance to root-knot nematodes (Meloidogyne spp.) is a top priority in grape breeding. Accessions of Vitis aestivalis Michx. resistant to root-knot nematodes have been identified. Vitis aestivalis is native to eastern North America and has historically been more important in breeding fruiting varieties than in rootstock development. This species is very difficult to propagate from cuttings, essentially precluding its direct use as a rootstock. Hybridization with easily propagated rootstock selections will be required to utilize any nematode resistance found in V. aestivalis. Progeny testing was used to assess the breeding value of potential sources of nematode resistance, including V. aestivalis and two related taxa. Three V. aestivalis accessions, all held in the U.S. National Plant Germplasm System collection, were evaluated. V. × slavinii Rehder is a natural hybrid of V. aestivalis and V. riparia that has been used in breeding rootstocks resistant to the dagger nematode Xiphinema index. Vitis nesbittiana Comeaux is native to Mexico; little evaluation of the nematode and disease resistance of this species has been reported. Vitis aestivalis, V. × slavinii, and V. nesbittiana were crossed with the rootstock varieties Riparia Gloire, 1616 Couderc, 99 Richter, Schwarzmann, and Dog Ridge. Hybrid seedling resistance was measured by counting the stained nematode egg masses visible per root system. Roots were stained in an eosin-Y solution (0.25 g/L for one hour) six weeks after inoculation with approximately 1500 second stage Meloidogyne spp. juveniles. Two populations of nematodes were used, representing populations either avirulent (M. incognita) or virulent (Meloidogyne spp.) on the grape rootstock Harmony. Several accessions showed useful levels of nematode resistance in their hybrid seedlings, but Vitis nesbittiana seedlings demonstrated especially high levels of resistance; this species has great potential for use in rootstock breeding. | |
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