Genetic architecture of berry aroma compounds in a QTL (quantitative trait loci) mapping population of interspecific hybrid grapes (Vitis labruscana × Vitis vinifera).

BACKGROUND: Although grapes accumulate diverse groups of volatile compounds, their genetic regulation in different cultivars remains unelucidated. Therefore, this study investigated the volatile composition in the berries of an interspecific hybrid population from a Vitis labruscana 'Campbell Early' (CE) × Vitis vinifera 'Muscat of Alexandria' (MA) cross to understand the relationship among volatile compounds and their genetic regulation. Then, a quantitative trait locus (QTL) analysis of its volatile compounds was conducted. RESULTS: While MA contained higher concentrations of monoterpenes and norisoprenoids, CE contained higher concentrations of C6 compounds, lactones and shikimic acid derivatives, including volatiles characteristic to American hybrids, i.e., methyl anthranilate, o-aminoacetophenone and mesifurane. Furthermore, a cluster analysis of volatile profiles in the hybrid population discovered ten coordinately modulated free and bound volatile clusters. QTL analysis identified a major QTL on linkage group (LG) 5 in the MA map for 14 monoterpene concentrations, consistent with a previously reported locus. Additionally, several QTLs detected in the CE map affected the concentrations of specific monoterpenes, such as linalool, citronellol and 1,8-cineol, modifying the monoterpene composition in the berries. As for the concentrations of five norisoprenoids, a major common QTL on LG2 was discovered first in this study. Several QTLs with minor effects were also discovered in various volatile groups, such as lactones, alcohols and shikimic acid derivatives. CONCLUSIONS: An overview of the profiles of aroma compounds and their underlying QTLs in a population of interspecific hybrid grapes in which muscat flavor compounds and many other aroma compounds were mixed variously were elucidated. Coordinate modulation of the volatile clusters in the hybrid population suggested an independent mechanism for controlling the volatiles of each group. Accordingly, specific QTLs with significant effects were observed for terpenoids, norisoprenoids and some volatiles highly contained in CE berries.

The potential aroma and flavor compounds in Vitis sp. cv. Koshu and V. vinifera L. cv. Chardonnay under different environmental conditions.

BACKGROUND: Koshu, a hybrid of Vitis vinifera L. and V. davidii Foex, is the most popular indigenous cultivar for wine production in Japan. However, little is known about the potential aroma compounds it contains and how environmental factors affect these. In this study, we obtained comprehensive profiles of the volatile (both glycosidically bound and free) and phenolic compounds that occur in koshu berries, and compared these with similar profiles for V. vinifera cv. chardonnay. We then compared the response of these two cultivars to bunch shading and the ripening-related phytohormone abscisic acid (ABA). RESULTS: Koshu berries contained significantly higher concentrations of phenolic compounds, such as hydroxycinnamic acid derivatives, and some volatile phenols, such as 4-vinyl guaiacol and eugenol, than chardonnay berries, which are thought to contribute to the characteristics of koshu wine. In addition, koshu berries had a distinctly different terpenoid composition from chardonnay berries. Shading reduced the concentration of norisoprenoid in both cultivars, as well as several phenolic compounds, particularly their volatile derivatives in koshu berries. The exogenous application of ABA induced ripening and increased the concentrations of lipid derivatives, such as hexanol, octanol, 1-nonanol, and 1-octen-3-ol. Multivariate and discriminant analyses showed that the potential aroma and flavor compounds in the berries could be discriminated clearly based on cultivar and environmental cues, such as light exposure. CONCLUSION: The unique secondary metabolite profiles of koshu and their different responses to environmental factors could be valuable for developing various types of koshu wines and new cultivars with improved quality and cultural characteristics. © 2018 Society of Chemical Industry.