No abstract

Phenolic compounds are components responsible of the sensorial characteristics of red wine. Indeed, they present important properties for human health. In the present work, the effects of combined in field treatments (water-stress and exogenous ABA) on phenolic accumulation were evaluated for berries and wine. The responses were assessed by UV-Vis and CZE. A differential phenolic regulation was observed under the same conditions and good correlations were achieved for grape and wine. ABA appears to regulate the content of each phenols under study depending on plant water-status. Although the effects of water-stress and exogenous ABA were similar in magnitude, our results support evidence suggesting that both affect different metabolic pathways. ABA supply increased catechin and malvidin synthesis for both water statuses while the resveratrol was enhanced only for water-stress. Indeed, ABA reduced the quercetin content for both water statuses. In vitro assays were carried out to estimate the effects of combined treatments (temperature-exogenous ABA) on anthocyanin accumulation in berries and pulp. These tests demonstrated that the effect of ABA was dependent on the hormonal level (207% for 0.5 g L -1 and 307% for 1 g L -1 of ABA). Effect of temperature varied according to the phenological state. In pulps, we detected an increase of anthocyanin after ABA treatments.

The production of grapevine secondary metabolites can be magnified by abiotic stresses or exogenous abscisic acid. Selected phenolic compounds were determined in grape and wine by gas chromatography/mass spectrometry with the aim to asses the physiological responses of plants submitted to water stress and hormonal treatments. Exogenous abscisic acids as well as postveraison water stress produce differential enhancements on phenolic accumulation on Cabernet Sauvignon grapes and such effects were reflected in wine. Resveratrol and malvidin were enhanced by both abscisic acid and water stress and the improvement produced by such factors was additive. On the other hand, the synthesis of gallic acid, (+) catechin, quercetin and caffeic acid was not stimulated by water deficit. Combined hormonal-water stress treatments produced three positive effects on wine quality; a) increments of blue compounds, b) increments of flavonols and flavan 3-oles that favor copigmentation of wines, c) higher antioxidant compounds concentration with the consequent health benefits.