Marker assisted selection for seedlessness in table grape breeding

Seedlessness is one of the most appreciated traits in the table grape (Vitis vinifera L.). The development of new seedless varieties is expensive and time consuming, involving the generation and selection of thousands of hybrids each year. In seeded × seedless crosses, seedlessness commonly segregates 1:1, so molecular markers allowing for the early identification of plants that will produce seedless berries are very useful. This early selection can lead to savings in maintenance and evaluation costs, and allows additional space for larger effective progenies. The variety Sultanina has been the main source of stenospermocarpic seedlessness in table grape breeding. In a previous work, we showed a 198-bp allele at the VMC7F2 microsatellite locus as a potential marker for selection of seedless genotypes due to its close linkage to the major effect seedless QTL, SDI. In this study, we show that stenospermocarpic bred cultivars share a main haplotype around this locus not found in seeded cultivars, which facilitating the development and use of marker assisted selection (MAS) strategies for the selection of seedless plants. In this way, VMC7F2 on its own can be a very useful marker for selecting seedless individuals from segregating crosses. A MAS program based on the presence of the 198-bp allele at VMC7F2 allows the reduction of the progeny size to 54%, selecting most of the seedless individuals. In addition, our results show the existence of other possible sources of stenospermocarpic seedlessness that could provide alternative sources of genetic variation for breeding of this trait.