From vineyard to a glass of wine: the effect of abscisic acid application on mouhtaro, a rare autochthonous variety of greece

Abstract

In a context of a sustainable viticulture, a new uprising strategy to improve grape and wine composition (or quality) is the exogenous application of plant activators(Gil-Muñoz et al., 2017). This treatment stimulates the biosynthesis of secondary metabolites in grape berries (Ruiz-García et al., 2013) In an open field, the plant hormone (Abscisic Acid), was applied on a red grape variety Mouhtaro cultivated at the Muses Valley (Askri, Viotia, Greece). Treatments were in triplicates during veraison in a randomized complete block design, with 10 vines in each replicate. Vines were sprayed at veraison stage, 3 and 6 days after the first application, at 2 different concentrations and grapes were harvested at optimum sugar maturity. Targeted UPLC-MS analysis was performed since It was suggested that exogenous ABA influence specific polyphenolic compounds. Then, classic red winemaking procedure was applied. The effect of exogenous ABA application on gene expression level was also examined. Standard analytical methods recommended by O.I.V. were used for grapes and wines as well as analysis for the phenolic composition. The pH increased in wines originated from grape berries treated with higher doses. Accordingly, phenolic compounds were higher in ABA-treated grapes and respective wines Similarly, the expression of specific genes encoding for key enzymes of the phenylpropanoid pathway was upregulated. As a consequence, Abscisic Acid affected the composition and sensory analysis of the wines differently. The unique wine profiles of Mouhtaro and their different responses to biostimulant factors could be valuable for developing various types of Mouhtaro red wines with improved quality