Search Results
Abstract
Various procedures were compared to identify a technique that would produce clear countable chromosomes in grape (Vitis L.) root tip squashes. Harvesting roots at 1100 hr from greenhouse-grown plants, pretreating with 0.02 m 8-hydroxyquinoline at 18°C for 6 hr, fixing in Farmer's Fluid at 26° for 24 hr, hydrolyzing in 1 n HCl at 60° for 1 hr, and staining with an altered form of carbol fuchsin gave the best results.
Abstract
Pollen from 157 genotypes of grape (Vitis sp.) were scanned for the occurrence of grains ≥30 μm in diameter. Eighteen diploid genotypes produced from 3% to 36% large pollen grains. Four of these produced distinctly oval-shaped grains. Eleven tetraploid genotypes produced from 47% to 87% large pollen. Large grains in diploid genotypes may be unreduced gametes that could be used in interploid crossing to breed hybrid tetraploids.
Abstract
Genetic analysis of 11 allozyme polymorphisms was performed on the progeny of ‘Cayuga White’ × ‘Aurora’, two complex interspecific grape (Vitis) hybrids. Segregation for most of the polymorphisms closely approximated monogenic Mendelian ratios, and eight new isozyme loci were defined for grape. Joint segregation analysis among the isozyme loci revealed three multilocus linkage groups. These results demonstrate that sufficient allozyme polymorphism exists in grape to establish many multilocus linkage groups and that this genetic analysis can be accomplished using extant progeny or progeny readily produced from highly heterozygous clones.
A project to develop a linkage map of the Vitis genome is underway using an interspecific hybrid grape population from `Cayuga White' × `Aurore'. The linkage map is based on 15 isozyme, 13 RFLP and more than 350 RAPD markers. This information is being combined with segregation data for viticulturally important traits including disease resistance to identify QTLs and mark simply inherited traits. Molecular markers, when linked with morphological traits, will find great application in map-based cloning and marker-assisted selection in grape breeding. We have also analyzed genome size of three genera of Vitacae (Ampelopsis, Parthenocissus and Vitis) and 15 Vitis species as well as 15 diploid cultivars using flow cytometry. DNA content varied from 0.84 to 1.40 pg/2C. The relative small genome size indicates that Vitis is a good candidate for molecular genome analysis. All this information will help us understand Vitis genome organization and reliability of identifying a gene linked to a marker in different populations.