ISHS Acta Horticulturae 623: XXVI International Horticultural Congress: Plant Genetic Resources, The Fabric of Horticulture's Future
RESPONSE TO ROOT-KNOT NEMATODES IN A VITIS MONTICOLA HYBRID POPULATION |
| Authors: | P. Cousins, M. Lauver |
| Keywords: | Meloidogyne, grape, rootstock, genetics, breeding |
| Abstract:
Accessions of the grape species Vitis monticola Buckley have been reported to be resistant to a root-knot nematode, Meloidogyne incognita, with resistance conditioned by a single dominant allele. New sources of root-knot nematode resistance are needed in grape rootstocks because of the emergence of nematode populations that are virulent on rootstocks with resistance derived from V. × champinii Planch.; these nematodes are termed “N virulent” or “Harmony virulent” populations in reference to their diagnostic grape rootstock host. Resistance against two types of root-knot nematodes was evaluated in seedlings of a cross of V. monticola and a grape rootstock. The male parent is an accession of V. monticola (accession DVIT 1376) held in the collection of the U.S. National Plant Germplasm System. The nematode resistance of this V. monticola accession has not been determined. 161-49C, a V. riparia × V. berlandieri hybrid, is the female parent of the population. This phylloxera resistant rootstock is known to be homozygous for the alleles conferring susceptibility to Meloidogyne incognita and also does not contribute resistance to Harmony virulent root-knot nematodes to its progeny. Resistance was evaluated in greenhouse pot culture using egg mass counts as a measure of nematode reproduction. Meloidogyne incognita (N avirulent) and N virulent (=Harmony virulent) nematodes (Meloidogyne sp.) were used to separately challenge the seedlings. The seedlings demonstrated segregation for resistance to N avirulent M. incognita nematodes in a pattern consistent with a 1:1 resistant:susceptible ratio. Vitis monticola accession DVIT 1376 is heterozygous for resistance to N avirulent M. incognita. However, the seedlings were very susceptible to N virulent root-knot nematodes. Vitis monticola is a source of nematode resistance, but accession DVIT 1376 does not offer resistance superior to that available in contemporary grape rootstock varieties. | |
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