Genetic dissection of quantitative trait loci for berry traits in interspecific hybrid grape (Vitis labruscana x Vitis vinifera)

Traits such as berry weight, firmness, and sweetness are important determinants of consumer choice and marketability of table grapes. Quantitative trait locus (QTL) analyses of berry traits have been conducted and markers have been developed mainly in Vitis vinifera. Interspecific hybrid grape (Vitis labruscana x V. vinifera) is particularly valuable in wet climates, but no QTL analyses of its berry traits have been reported. Using 98 F-1 individuals from a V. labruscana x V. vinifera cross, we performed QTL analysis of eight berry traits. We identified eight related QTLs-two for berry cracking, one for berry weight, two for firmness, one for harvest date, one for soluble solids concentration, and one for titratable acidity. Among them, the QTL for berry weight on linkage group (LG) 11 had the strongest and most stable effect over 4 years. This QTL might provide a reliable marker, as variations in berry weight are due mainly to genotype effects. The alleles for increasing berry weight and for increasing berry cracking were linked on LG 11. These results will contribute to marker-assisted selection in table grape breeding programs.