Background: Symptoms of grapevine leafroll disease (GLRD) in red-fruited wine grape (Vitis viniferaL.) cultivars consist of green veins and red and reddish-purple discoloration of inter-veinal areas of leaves. The reddish-purple color of symptomatic leaves may be due to the accumulation of anthocyanins and could reflect an up-regulation of genes involved in their biosynthesis.Results: We examined six putative constitutively expressed genes,Ubiquitin, Actin,GAPDH,EF1-a, SANDandNAD5, for their potential as references for normalization of gene expression in reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). Using thegeNormprogram, a combination of two genes (ActinandNAD5) was identified as the stable set of reference genes for normalization of gene expression data obtained from grapevine leaves. By using gene-specific RT-qPCR in combination with a reliable normalization factor, we compared relative expression of the flavonoid biosynthetic pathway genes between leaves infected withGrapevine leafroll-associated virus 3(GLRaV-3) and exhibiting GLRD symptoms and virus-free green leaves obtained from a red-fruited wine grape cultivar (cv. Merlot). The expression levels of these different genes ranged from two- to fifty-fold increase in virus-infected leaves. Among them,CHS3,F3'5'H,F3H1,LDOX,LAR1andMybA1showed greater than 10-fold increase suggesting that they were expressed at significantly higher levels in virus-infected symptomatic leaves. HPLC profiling of anthocyanins extracted from leaves indicated the presence of cyanidin-3-glucoside and malvidin-3-glucoside only in virus-infected symptomatic leaves. The results also showed 24% higher levels of flavonols in virus-infected symptomatic leaves than in virus-free green leaves, with quercetin followed by myricetin being the predominant compounds. Proanthocyanidins, estimated as total tannins by protein precipitation method, were 36% higher in virus-infected symptomatic leaves when compared to virus-free green leaves.Conclusions: The results, the first example to our knowledge, showed that modulation of the flavonoid biosynthetic pathway occurred in GLRaV-3-infected leaves of a red-fruited wine grape cultivar (cv. Merlot) leading tode novosynthesis of two classes of anthocyanins. These anthocyanins have contributed to the expression of reddish-purple color of virus-infected grapevine leaves exhibiting GLRD symptoms.

Four regulated deficit irrigation (RDI) regimes were applied to Cabernet Sauvignon grapes, which were analyzed for phenolics and also made into wine over three consecutive growing seasons. Relative to an industry standard regime (IS), yield was reduced over the three years by 37% in a full-deficit (FD) regime and by 18% in an early deficit (ED) regime, whereas no yield reduction occurred with a late deficit (LD) regime. Relative to IS, skin anthocyanin concentration (fresh weight basis) was 18% and 24% higher in ED and FD, respectively, whereas no effect was seen in LD. Seed tannin concentration was 3% and 8% higher in ED and FD, respectively, relative to the other two RDI regimes, whereas seed tannin content (amount per berry) was higher in IS than in FD. There were no practically relevant effects on the basic chemistry of the wines. The finished wines showed concentrations of tannins and anthocyanins that generally mirrored observed differences in skin and seed phenolic concentrations, although these were amplified in FD wines. Descriptive sensory analysis of the 2008 wines showed that FD wines were the most saturated in color, with higher purple hue, roughness, dryness and harshness, followed by ED wines, whereas IS and LD wines were less saturated in color and with higher brown and red hues. Overall, FD and ED seemed to yield fruit and wine with greater concentrations of phenolics than IS and LD, with the additional advantage of reducing water usage. However, these apparent benefits need to be balanced out with reductions in crop yields and potential long-term effects associated with pre-véraison water deficits.

Background and Aims Anecdotal evidence suggests that there may be a synergistic effect of ethanol (EtOH) and prolonged skin contact on the extraction of certain phenolics that may negatively impact wine sensory properties. The combined effect of extended maceration (EM) and EtOH concentration was studied during winemaking and bottle ageing. Methods and Results The evolution of phenolics and colour components was followed for up to 1 year of bottle ageing. Harvest skins and seeds and those obtained from the pomace after maceration were also analysed. Sensory attributes were studied by Quantitative Flavour Profiling. The relationship between the chemical and sensory data was explored with Partial Least Square Regression. EtOH concentration differing by 1.2% v/v had no effect on tannin and anthocyanin extraction, colour, tannin mean degree of polymerisation, polymeric pigment formation and recovery of anthocyanins and tannins in the pomace after maceration. The maceration length defined the chemical and sensory profile of the wines. The tannin content of wines produced with EM was mainly derived from seed tannins, whereas control wines had a balanced proportion of seed and skin tannins. The anthocyanin concentration was lower in EM wines, whereas polymeric pigments and tannins were predictors of astringency. In control wines, perceived red colour was associated with anthocyanins, vitisins, a* (red component), and small polymeric pigments. Significance of the Study Evidence of the nature and interrelation of the chemical and sensory composition of wines obtained with EM is provided. Major chemical features responsible for the sensory properties of wines produced by two contrasting skin contact regimes are identified.

This study compared own-rooted vines and different scion/rootstock combinations in arid eastern Washington, where vineyards are primarily deficit-irrigated and own-rooted. The performance of Chardonnay, Merlot, and Syrah on five rootstocks (5C, 140Ru, 1103P, 3309C, and 101CU) or on their own roots was evaluated with 10 field replicates over three vintages (2007–2009) in the Yakima Valley AVA. At harvest, two field replicates each were combined to make five winemaking replicates; 45 kg of grapes were made into wine. The grape variables measured were total soluble solids (TSS), titratable acidity (TA), pH, potassium (skin, seeds and pulp), tannins (skin and seeds), and anthocyanins. Wine variables measured were ethanol, TA, pH, potassium, tannins, total iron reactive phenolics, anthocyanins, and polymeric pigments. Rootstock caused few significant differences in fruit and wine composition and instead the dominant factors were scion and, to a lesser extent, vintage. All fruit and wine variables measured with the exception of TSS varied significantly with scion. Only TSS and berry size were consistently affected by vintage. Rootstock had no effect on grape anthocyanins and tannins. However, significant but small and variable effects were observed for wine anthocyanins and tannins. Wines from own-rooted vines tended to have somewhat higher pH, potassium, and total tannin than did wines from grafted vines. The relationships between fruit and wine for anthocyanins and tannins were not straightforward and warrant further research.

Selected winemaking conditions were applied to fruit with ~20.3 and ~24.9 Brix over two seasons. Merlot grapes were harvested 33 (2011) and 34 (2012) days apart. At each harvest, half of the must was adjusted to emulate the other harvest’s soluble solids content to evaluate the effect of ethanol (EtOH) on phenolic extraction at different fruit maturities. Additionally, two maceration lengths of 10 days (control) and 30 days (extended maceration; EM) were tested. Control wines had significantly higher anthocyanin content, saturation, and red color component, whereas EM wines had enhanced tannin extraction from seeds, lower anthocyanin content, lower saturation, higher hue, and higher large polymeric pigment content. EtOH differences up to 2.7% (v/v) showed no significant effect on tannin and anthocyanin extraction, suggesting a minor role of this solvent under standard winemaking conditions. The later harvest date had a prevailing and positive effect on the sensory profile of the wines over winemaking factors such as maceration length and EtOH treatments. Wines from the early harvest fruit were defined by fresh vegetal character, acidity, and low color saturation. Wines from the late harvest fruit were defined by viscous mouthfeel, sweet taste, and fruit-derived aromas. Extended maceration shifted the sensory profile toward higher astringency, lighter and yellower color components, and cooked vegetal aromas. Chaptalization of early harvest fruit to 25 Brix shifted the sensory profile from cooked and fresh vegetable characters toward sweet taste, alcoholic, floral, chocolate/caramel attributes, astringency, and viscous mouthfeel. Overall, unripe fruit and the application of extended maceration had a negative impact on the sensory profile of the wines, whereas chaptalization of unripe fruit yielded wines with an improved sensory profile.