ISHS Acta Horticulturae 623: XXVI International Horticultural Congress: Plant Genetic Resources, The Fabric of Horticulture's Future
SEGREGATION OF RESISTANCE TO ROOT-KNOT NEMATODES IN A VITIS VULPINA HYBRID POPULATION |
| Authors: | P. Cousins, M. Lauver |
| Keywords: | Meloidogyne, grape, rootstock, genetics, breeding |
| Abstract:
The root-knot nematode (Meloidogyne spp.) resistance of a seedling population derived from Vitis vulpina L. was evaluated to investigate the genetic control of nematode resistance in this grape species. The female parent of the population is the phylloxera resistant grape rootstock 161-49C, a V. riparia × V. berlandieri hybrid. This rootstock is known to be homozygous for the alleles conferring susceptibility to Meloidogyne incognita and also does not contribute resistance to N virulent (= Harmony virulent) root-knot nematodes to its progeny. The male parent is an accession of V. vulpina (accession DVIT 1280) held in the collection of the U.S. National Plant Germplasm System. The nematode resistance of this V. vulpina accession has not been determined, but root-knot nematode resistance has been reported in grape rootstocks with V. vulpina in their parentage. Resistance was assessed in greenhouse pot culture with nematode reproduction measured by counting egg masses present on seedling roots six weeks after inoculation with second stage juvenile nematodes. Three nematode populations were used to evaluate seedling resistance. Two of the nematode populations are virulent on Harmony, a grape rootstock resistant to most Meloidogyne incognita populations. The third nematode population is a Meloidogyne incognita population avirulent on Harmony. In each of the three nematode population screenings the grape seedlings segregated in a pattern consistent with a 1:1 ratio of resistant:susceptible. However, since each seedling was challenged by only a single nematode population, it cannot yet be determined if the resistance to N virulent and N avirulent nematodes is due to the same or different alleles. The V. vulpina parent of the population, accession DVIT 1280, is heterozygous for at least one dominant allele conferring resistance to root-knot nematodes. | |
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