Validation of a Molecular Marker for Seedlessness in Muscadine Grapes

Seedlessness is a crucial trait in the commercial success of table grapes, and the development of seedless cultivars is critically important in efforts to increase the consumer appeal of fresh-market muscadine grapes (Vitis rotundifolia).  Muscadine is a member of the subgenus Muscadinia, while Vitis vinifera and several other grape species are members of the subgenus Euvitis.  Because Euvitis and Muscadinia have different chromosome numbers, introducing stenospermocarpic seedlessness into Muscadinia from Euvitis is challenging. However, the UGA breeding program has recently obtained the complex hybrids NC74CO49-10 and DRX60-40, which are able to serve as bridges between the two subgenera.  Previous research has located a functional candidate gene for stenospermocarpic seedlessness, VvAGL11, in V. vinifera.  An STS marker located in the regulatory region of VvAGL11 allows for the detection of the dominant seedless allele in a wide variety of Euvitis genotypes.  The objective of this study was to test the VvAGL11 STS marker in two hybrid progenies in order to determine its usefulness for predicting seedlessness in Euvitis × Muscadinia hybrids.  After assessing its performance in seedless Euvitis cultivars, the hybrid progenies, and a variety of muscadine cultivars, we were able to validate the marker.  This marker has excellent potential to facilitate the breeding of new seedless muscadine cultivars.