Impact of hormone applications on ripening-related metabolites in Gewürztraminer grapes (Vitis vinifera L.): The key role of jasmonates in terpene modulation

Terpenes play a formative role in grape and wine flavor, particularly for high-terpenic cultivars. Differences in terpene profiles influence grape varietal character and vintage quality. Little is known about the endogenous factors controlling terpene biosynthesis in grape. Through multiple experiments, six hormones (abscisic acid, ABA; ethylene, ETH; jasmonic acid, JA; methyl jasmonate, MeJA; indole-3-acetic acid, IAA; 1-naphthaleneacetic acid, NAA) that either promote or repress ripening were applied to Gewürztraminer clusters near veraison to gauge their effect on ripening and terpene biosynthesis. Jasmonates (JA, MeJA) increased terpene concentrations and the expression of terpene genes in grapes. Such increases were not associated to increases of other ripening-related metabolites such as sugars or anthocyanins. MeJA also affected the expression of several hormone related genes, increased IAA levels, and reduced sugar and anthocyanin concentration in grapes. This research provides novel insights into terpene regulation by ripening-related hormones and jasmonates in grapes.