The wine grape, Vitis vinifera [L.] (2n = 38), is believed to have evolved through selection of wild progenitors in the Middle East and Europe over the last 10,000 years. The current domesticated form is a worldwide economically important commodity, utilized for wine, juice, fresh and dried fruit, and food products. The North American grape, Muscadinia rotundifolia [Michx.] Small (2n = 40), is primarily grown in its native habitat of the southeastern United States. Muscadinia rotundifolia is naturally resistant to many of the pests and pathogens that hinder V. vinifera production. However, the wine made from this grape is considered inferior and has relegated the grape to be a relatively minor commodity. Genetic mapping of 123 V. vinifera × M. rotundifolia (VR) F1 hybrids from four related populations was conducted to assemble the first reported haploid map of M. rotundifolia. This is the first step in generating markers associated with traits of interest for markers-assisted breeding. A total of 56 simple sequence repeat (SSR) and 73 amplified fragment length polymorphism (AFLP) markers were used to assemble a consensus haploid map of M. rotundifolia which covered 20 linkage groups. The cumulative map length was 1270.8 cM, with an average distance of 10.1 cM between markers. The locus controlling sex determination was found to be linked to SSR markers, which have previously been shown to be tightly linked to the trait in Vitis species. Rooting of dormant canes of VR hybrids was shown to be a complex multigenic trait. Four Quantitative Trait Loci (QTLs) were identified that contribute to a total of 51.9% of the rooting phenotypic variance. The amplification patterns of SSR markers in M. rotundifolia compared to Vitis spp. suggests that there are both highly conserved and highly diverged genomic regions. Genetic mapping supports previously characterized cytological chromosomal behavior that concluded approximately two-thirds of chromosomes are conserved between the genera.
Genetic diversity of 24 wild sub-populations of M. rotundifolia from North and South Carolina, and Florida was measured and compared with wild accessions collected in the 19th century. A total of 278 wild accession of M. rotundifolia were genotyped at 15 SSR loci for population structure analysis. The total mean genetic diversity (observed heterozygosity of 0.485) was primarily due to differences among individuals within sub populations (83.3%). The mean genetic diversity is lower than values reported for wild forms of V. vinifera (0.597), and is most likely attributed to divergence between the genera at the loci examined.
Introgression of disease resistance from M. rotundifolia into Vitis spp. is potentially useful for the development of new cultivars for table and wine grape production as well as rootstocks. Muscadinia rotundifolia is not utilized as a rootstock due to the inability to form roots from dormant cuttings, and graft incompatibility with Vitis species. Advances in rootstock breeding were accomplished by identifying three partially fertile F1 hybrids of North American species of Vitis and M. rotundifolia (herein referred to as VM hybrids to distinguish these vines from hybrids with V. vinifera in their pedigree). These VM hybrids were used to generate the next generation of rootstocks that may provide superior protection against phylloxera, nematodes, Pierce‘s disease, and suppress the disease symptoms of Grapevine Fanleaf Virus (GFLV).
|Advisor:||Walker, Micheal A.|
|Commitee:||Chetelat, Roger T., Gradziel, Tom|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 71/12, Dissertation Abstracts International|
|Keywords:||Diversity, Genetic map, Grape, Muscadinia rotundifolia, Vitis vinifera|
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