Date of Graduation

Summer 2021


Master of Science in Plant Science (Agriculture)


College of Agriculture

Committee Chair

Chin-Feng Hwang


Acidity and sugar content are among the grape berry quality traits that influence wine quality. Despite advantageous environmental tolerances of Vitis aestivalis-derived ‘Norton’, its acid and sugar concentrations often deviate from expectations set for V. vinifera. Identification of the genetic determinants of malic acid, tartaric acid, pH, and total soluble solids (TSS) can assist in the improvement of new hybrid cultivars. For this purpose, a ‘Norton’ and V. vinifera ‘Cabernet Sauvignon’ hybrid mapping population containing 223 individuals was used to construct a linkage map containing 384 simple sequence repeat (SSR) and 2084 genotyping-by-sequencing (GBS)-derived single nucleotide polymorphism (SNP) markers. The resulting map was 1441.9 cM in length with an average inter-marker distance of 0.75 cM and spanned 19 linkage groups (LGs). Quantitative trait loci (QTL) were detected for malic acid, tartaric acid, and pH. QTLs for malic acid (LG 8) and pH (LG 6) were observed across multiple years and explained approximately 17.7% and 18.5% of the phenotypic variation, respectively. Additionally, QTLs for tartaric acid were identified on linkage groups 1, 6, 7, 9, and 17 in single-year data. The QTLs for tartaric acid explained between 8.8-14.3% of the phenotypic variation. The markers linked to these QTLs can be used to improve hybrid cultivar breeding through marker-assisted selection.


Vitis aestivalis, ‘Norton’, simple sequence repeats, single nucleotide polymorphism, quantitative trait loci, malic acid, tartaric acid, total soluble solids, pH

Subject Categories

Fruit Science | Plant Breeding and Genetics | Viticulture and Oenology


© Karlene Louise Negus

Open Access