Cadle-Davidson, Molly M. , Owens, Christopher L .
Radiation of the grape retroelement (GRET1) in Vitis spp. of the grapevine germplasm repository.
The mutation responsible for 95% of white-fruited Vitis vinifera is the insertion of retroelement Gret1 into the promoter of VvMybA1. To date, a single color locus has been identified causing this phenotype despite the existance of many grape fruit color bud sports. Due to the geographic isolation and domestication pressure differences between V. vinifera and North American species, it was assumed that radiation of this element would reflect these differences. The presence and copy number of Gret1 was assessed using quantitative PCR on the Vitis collection held at the Plant Genetic Resources Unit in Geneva, NY, representing 21 different species in addition to V. vinifera. Of these, only five (including vinifera and the interspecific hybrids) are known to contain white accessions. Statistical analysis revealed that Gret1 copy number is associated with species as well as with color within species. Genomic regions regions surrounding Gret1 were sequenced in white V. vinifera, hybrid, labrusca, aestivalis and riparia accessions to identify candidate genes for alternate white alleles. Sequence analysis lead to the discovery of Gret1 upstream of Phytochrome A, Flavonoid 3’,5’-hydroxylase (F3’5’H) and Caffeic acid 3-O-methyltransferase (COMT). F3’5’H and COMT insertions were associated with white berry color suggesting a Gret1 insertion site bias.
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1 - USDA-ARS, Grape Genetics Research Unit, 630 W. North St, 308 Sturtevant Hall, Geneva, NY, 14456, USA
2 - USDA-ARS, Grape Genetics Research Unit
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM