2019 ASHS Annual Conference

Muscadines are classified as black- or bronze-fruited. The anthocyanin content in the skins of bronze muscadines is usually less than 100 µg.g^-1, while the anthocyanin content of black-fruited muscadines ranges from less than 1000 µg.g^-1 to over 5000 µg.g^-1. A glutathione S-transferase gene, VrunGST4, has been identified as a candidate gene for berry color in muscadines. A molecular marker was developed within VrunGST4 to distinguish between muscadine genotypes with bronze (T:T), heterozygote black (C:T), and homozygote black (C:C) berries. The objectives of this study were 1) to determine the correlation between berry skin color and total anthocyanin content, 2) to calculate additive and dominance effects of VrunGST4 for total anthocyanin content in two biparental F₁ muscadine populations (‘Supreme’ x ‘Nesbitt’ and ‘Black Beauty’ x ‘Nesbitt’) screened with the intragenic VrunGST4 marker, and 3) to determine whether VrunGST4 affects proanthocyanidin content in berry seeds in the biparental F₁ muscadine populations. No correlation was found between hue and lightness of the berry skin and anthocyanin content of black-fruited genotypes in either population. However, there was a slight correlation (r = 0.64) between anthocyanin content and berry skin chroma in the ‘Black Beauty’ x ‘Nesbitt’ population. There was no difference in total anthocyanin content of C:C and C:T genotypes in either population, indicating that VrunGST4 had a completely dominant gene action. The total anthocyanin content of the berry skins from black-fruited genotypes in the ‘Black Beauty’ x ‘Nesbitt’ was approximately four times higher than black-fruited genotypes in the ‘Supreme’ x ‘Nesbitt’ population. This finding suggested that other genetic loci may contribute to variation in total anthocyanin content in black-fruited muscadines. To investigate the role of VrunGST4 on proanthocyanidin content in the seeds of muscadine berries, we are measuring total proanthocyanidins in seeds harvested from C:C, C:T, and T:T genotypes in the ‘Supreme’ x ‘Nesbitt’ and ‘Black Beauty’ x ‘Nesbitt’ populations.