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The classification of grapevine cultivars into isohydric and anisohydric categories depends on their ability to close stomata under conditions of low soil water availability or high atmospheric demand. This study aimed to compare the responses of Grenache, classified as isohydric, and Cabernet Sauvignon, classified as anisohydric, both grafted onto Richter 110 rootstock, and subjected to severe drought stress. Three cycles of drought stress were applied, followed by watering, while a well-watered treatment served as the control. Stomatal conductance and stem water potential were measured at predawn and midday during the drought cycles, and primary metabolites were analyzed in leaves and roots using gas chromatography. We found that Grenache had significantly higher stomatal conductance than Cabernet Sauvignon under both well-watered and water-stressed conditions. There were no significant differences in stem water potential between the two varieties, but the control treatment maintained a higher stem water potential at predawn and midday for both varieties. Primary metabolite analysis showed that both varieties accumulated sugars and polyols in their leaves and roots under drought stress, while organic acids were more abundant in leaves than in roots. Overall, the results suggest that the hydric behavior of grapevines depends on the intensity and duration of drought stress. In this study, both varieties exhibited near-isohydric behavior by regulating stomatal closure under drought stress. The metabolites identified in this study may serve as potential biomarkers of water drought stress in Grenache and Cabernet Sauvignon grapevines under the conditions of this experiment. [ABSTRACT FROM AUTHOR]

The influence of regulated deficit irrigation on the anthocyanin composition in Cabernet Sauvignon grape skins throughout ripening and when grown in a warm geographic area for two consecutive seasons was investigated. The assay was carried out on own-rooted Cabernet Sauvignon plants maintained under three irrigation regimes (i.e., T1 = 12 L h−1 (90% of ETp), T2 = 6 L h−1 (60% of ETp) and T3 = 2 L h−1 (30% of ETp)) from veraison until harvest. The results showed that the concentration of total anthocyanins varied among the three groups. In terms of the different fractions of anthocyanins, mild water stress generated slight changes with a different behavior between the 2014 and 2015 seasons, although the pattern of accumulation was similar. The trihydroxylated anthocyanins were much higher in concentration than the dihydroxylated counterparts in both seasons, with no significant differences among irrigation treatments. The water status did not produce differences in terms of the different anthocyanin proportions at harvest, which could indicate that the different irrigation treatments did not induce a greater accumulation of one or another type of anthocyanin. [ABSTRACT FROM AUTHOR]

This study investigates the chemical composition and sensory properties of wines from Cabernet Sauvignon vines grown under controlled water deficit in two consecutive seasons. The wines were made from fruit of grapevines that were maintained under three water status levels (i.e. T1, Ψ stem  = −0.8 MPa; T2, Ψ stem  = −0.9 MPa; T3, Ψ stem  = −1.0 MPa) from veraison until harvest. Our results suggest that wine phenolic composition was affected by controlled water deficit, where T3 wines exhibited a higher concentration of total phenols, total anthocyanins and chroma (C*) in both seasons. These results coincide with the principal component analysis that indicated a substantial separation between years and deficit irrigation. We found that irrigation treatments only produce differences in concentration, but not in anthocyanin composition in both years. Separation of proanthocyanidins fractions by solid phase extraction using Sep-Pak Plus tC 18 cartridges showed only a change in the concentration of the monomeric fraction in 2014 season, but not in the proportion of the different proanthocyanidins fractions in both seasons. Finally, the sensory composition of wines showed differences that depend on the season and resulted in more red fruits, more fullness perception in mouth and more color intensity in wines from less irrigated treatments. [ABSTRACT FROM AUTHOR]

Summary: The effect of three water status level and two harvest date 55 and 64 days after veraison (DAV) on phenolic and sensory composition of Cabernet Sauvignon wines were investigated. The later harvest date led to wine with a higher alcohol content. Total phenols varied from 1439.66 to 1643.08 mg L−1 with higher values at 64 DAV. No differences were observed between irrigation treatments. For total tannins and anthocyanins, no differences were found between harvest date. Separation of proanthocyanidins by Sep‐Pak Plus tC18 cartridges showed only differences in concentration but not in the proportion of proanthocyanidin fractions. The wines from the most restricted treatment had a better colour and the same aroma of red fruits, persistence, astringency, fullness and bitterness, as the wine from the treatment with highest irrigation. Under the assay conditions, it was possible to obtain wines with a similar chemical and sensory composition earlier and using less irrigation water. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Controlled water deficits affect grape berry physiology and the resulting wines, with volatile composition being the one of the affected parameters. However, there is a potential disconnect between aromatic maturity and sugar accumulation. Accordingly, the effects of three different water status levels over two growing seasons (2014 and 2015) and two different harvest dates on the aroma compounds from Cabernet Sauvignon wines were studied. Volatile compounds were determined using headspace solid phase microextraction coupled with gas chromatoghraphy/mass spectrometry. RESULTS: Around 45 volatile compounds were determined in the wines and, among these, esters were affected the most, presenting lower concentrations when the most restrictive water treatment was applied in both years. By contrast, volatile acids presented the highest concentrations when the lowest level of irrigation was applied. On the other hand, a delay in harvesting produced an increase in the total amount of volatile compounds in samples from the most restrictive water treatment. These results are coincident with a principal component analysis that indicated a great separation between years, deficit irrigation treatments and harvest dates. CONCLUSION: The results of the present study suggest that a low water supply had a negative effect on the aromatic potential of wines at a similar ripening stage. However, this effect could be countered by harvesting at a later date. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The influence of controlled water deficit on the phenolic composition and gene expression of VvLAR2 , VvMYBPA1 , VvMYBPA2 and VvMYB4a in Cabernet Sauvignon grape skins throughout ripening was investigated. The assay was carried out on own-rooted Vitis vinifera plants cv. Cabernet Sauvignon in a commercial vineyard from veraison until commercial harvest. Three irrigation regimes were used from veraison until harvest with the following treatments: T1: 3.6 mm day −1 ; T2: 1.8 mm day −1 and T3: 0.3 mm day −1 . The content of total phenols and total anthocyanins in grape skins increased during ripening, but water deficit did not produce differences among treatments in the total anthocyanin concentration. Proanthocyanidins (PAs) decreased throughout ripening, although approximately 25 days after veraison (DAV), their content slightly increased. This effect was more pronounced in the most restrictive treatment (T3). A similar pattern was observed in the transcript abundance of VvLAR2 , VvMYBPA1 and VvMYB4a . PAs separation revealed differences in concentration but not in the proportion among fractions among the irrigation treatments. Additionally, controlled water deficit increased the mean degree of polymerization and the flavan-3-ol polymeric concentration in grape skins throughout ripening but with no effects on the extent of PAs galloylation. Our results suggest that the water status of Cabernet Sauvignon grapevines affects the gene expression for proteins involved in the synthesis of PAs, increasing their concentration and also their composition, with further evidence for the efficacy of a convenient, controlled water deficit strategy for grapevine cultivation. [ABSTRACT FROM AUTHOR]