Exploring Quantitative Trait Loci for Anthocyanin Content in Interspecific Hybrid Grape (Vitis labruscana × Vitis vinifera)

Anthocyanins affect the coloration of grape berry skin, which is an important determinant for consumer choice and grape marketability. Molecular mechanisms for anthocyanin accumulation in grape skin have been intensively studied. In Vitis vinifera, two adjacent MYB transcriptional factors, VvMybA1 and VvMybA2, regulate anthocyanin biosynthesis, and this set of genes are regarded as a MYB haplotype. Interspecific hybrid grape originated from a Vitis labruscana × V. vinifera is particularly valuable in wet climate regions, yet few studies on anthocyanin accumulation in this hybrid have been published. Using 98 individuals originated from a V. labruscana × V. vinifera cross, we constructed the parental and consensus linkage maps with simple sequence repeat markers, and performed quantitative trait locus (QTL) analysis of anthocyanin content. Distribution of anthocyanin content showed continuous variation, which was mainly due to the effect of genotypes. We detected QTLs for anthocyanin content in linkage groups 2 (MYB haplotype), 8 (A8-QTL2) and 14 (A14-QTL3). Moreover, the model-fitting with a multiple linear model was investigated in practical breeding populations, where we used anthocyanin content of individuals as a response variable, and SSR genotypes located nearest QTL regions as explanatory variables. As a result, the best model for explaining anthocyanin content comprised MYB haplotype, A8-QTL2 and A14-QTL3 regions as explanatory variables. These results suggest that A8-QTL2 and A14-QTL3 could be novel loci that affect anthocyanin content in grape berry skin.