The responses of Vitis vinifera L. cv. Malbec to different solar ultraviolet-B radiation (UV-B) levels were assessed in two contrasting situations, under sunlight with full UV-B (+UV-B) and filtered UV-B (-UV-B), in three different locations at 500, 1000, and 1500 m above sea level (asl). To evaluate the effects of radiation, a simple, accurate, and rapid method for the separation and simultaneous determination of representative phenolic compounds in grape berry skins by capillary zone electrophoresis was developed. Separation was carried out in less than 20 min with 20 mM sodium tetraborate buffer containing 30% methanol, pH 9.00. The procedure is fast and reliable, and extracted grape berry skins can be directly analyzed without prior sample cleanup procedure. Berry skins from the +UV-B treatment at 1500 m asl showed the highest levels of total polyphenols anthocyanins, and resveratrol, compared with the -UV-B treatment at this altitude.

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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.