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Tia grapevine is a genetic dwarf with shortened internodes and produces inflorescences instead of tendrils. Tia resulted from selection of a dwarf seedling in a population derived from controlled hybridization of the rootstock Freedom, Vitis hybrid (pistillate flowered seed parent, unpatented) with the dwarf grape variety Pixie (perfect flowered pollen parent, unpatented), Vitis vinifera L. The original Tia vine grew from a seed planted in 2007 and the cross pollination that created the seed was made on June 13, 2006.
Tia is a black fruited seeded grape. The flowers are pistillate and self-infertile. Cross pollination for hybridization and population development are simple because the flowers do not require emasculation. Instead of tendrils, Tia bears inflorescences. Flowering is continuous on actively growing Tia vine, especially on branches. Since Tia flowers are pistillate, they do not self-fertilize. Tia is a genetic dwarf grapevine with internode length one-third or less of the internode length of related non-dwarf varieties and germplasm. Tia has reduced sensitivity to gibberellins; the reduced sensitivity results from a natural genetic mutation and accounts for the production of inflorescences instead of tendrils and the shortened internodes.
Tia is germplasm for genetics, genomics, breeding, pathology, physiology, and other grapevine research. Crosses with Tia are expected to segregate for the semi-dominant dwarfing character that Tia inherited from Pixie. The space required per experimental grapevine is greatly reduced and Tia and other dwarf grapevines can be grown in the greenhouse to maturity without the need to plant them in a vineyard. Since the vines can be grown in the greenhouse to maturity, research is accelerated as it may be conducted year round. The continuous flowering habit of Tia provides researchers with the opportunity to study flowers and berries at all stages of development throughout the year. Tia carries the N allele for resistance to root-knot nematodes. The N allele carried by Tia grapevine was inherited from its Freedom rootstock seed parent, which is homozygous for the N allele for root-knot nematode resistance. Populations developed from crosses of Tia with nematode susceptible grapevine varieties or germplasm are expected to segregate for the N allele for root-knot nematode resistance. There is no other known dwarf germplasm that carries the N allele for root-knot nematode resistance.
Tia is different from Pixie because Tia is pistillate flowered and Pixie is perfect flowered. Because Tia is pistillate flowered and therefore self-infertile, Tia can be easily used as a seed parent in breeding and crossing because the flowers of Tia do not need to be manually emasculated. |
