Identification of Novel Quantitative Trait Loci Associated with Table Grape Fruit Quality Characteristics in a Segregating Population and Transferability of Existing Quality Markers

Grape (Vitis) production and fruit quality traits such as cluster size, berry shape, and timing of fruit development are key aspects when selecting cultivars for commercial production. Molecular markers for some, but not all, of these traits have been identified using biparental or association mapping populations. Previously identified markers were tested for transferability using a small (24 individual) test panel of commercially available grape cultivars. Markers had little to no ability to differentiate grape phenotypes based on the expected characteristics, except the marker for seedlessness. Using a biparental interspecific cross, 43 quantitative trait loci (QTLs) (previously identified and new genomic regions) associated with berry shape, number, size, cluster weight, cluster length, time to flower, veraison, and full color were detected. Kompetitive allele -specific polymerase chain reaction markers designed on newly identified QTLs were tested for transferability using the same panel. Transferability was low when use types were combined, but they were varied when use types were evaluated separately. A comparison of a 4 -Mb region at the end of chromosome 18 revealed structural differences among grape species and use types. Table grape cultivars had the highest similarity in structure for this region (>75%) compared with other grape species and commodity types.