ASHS 2024 Conference

Hybrid grapevines (Vitis spp.) grown in cold climate regions have fruit chemistries which do not adhere to the standard ranges of European wine grapes (Vitis vinifera L.) that many consumers may be accustomed to. The variation in fruit chemistry observed in hybrid grapevines is driven by a combination of genetics of parent material, which often builds on wild Vitis species, and the environmental conditions of production, which are often characterized by low heat accumulation and limited duration of growing season. Characterizing the genetic basis of fruit attributes enables breeders to understand and improve the relative quality of interspecific grapevines for future cultivar development. To address this knowledge gap for breeders, an incomplete diallel population of interspecific hybrid grapevines was assessed over a period of three years. Fruit chemistry (total soluble solids, pH, total acidity, glucose, fructose, malic acid, tartaric acid, citric acid, and yeast assimilable nitrogen content) and berry mass were examined at three distinct time points within each growing season to yield a total of nine phenotyping events. Best linear unbiased predictors (BLUPs) calculated from multi-year phenotype data were then interrogated via GWAS analysis to identify significant marker-trait associations. Chromosomes 16, 6, and 17 were noted to have the highest number of associations observed. To further understand the specificity of observed loci, gene annotation was conducted to reveal several important genes potentially related to the phenotypes. Due to the quantitative nature of fruit attributes, genomic selection strategies were explored to assess their accuracy for improving population performance in a systematic manner. Cumulatively, this analysis provides important information regarding the role of genetics in major fruit traits of interspecific cold hardy grapevines, regions of interest for fine mapping, and strategies for genomic selection. These analyses contribute towards the goals of improving breeding efficiency and selection accuracy to reduce generation timeline in grapevines.