Anthocyanins are flavonoid compounds responsible for red/purple colors in the leaves, fruit, and flowers of many plant species. They are produced through a multistep pathway that is controlled by MYB ...transcription factors. VvMYBA1 and VvMYBA2 activate anthocyanin biosynthesis in grapevine (Vitis vinifera) and are nonfunctional in white grapevine cultivars. In this study, transgenic grapevines with alteredVvMYBAgene expression were developed, and transcript analysis was carried out on berries using a microarray technique. The results showed that VvMYBA is a positive regulator of the later stages of anthocyanin synthesis, modification, and transport in cv Shiraz. One up-regulated gene,ANTHOCYANIN 3-O-GLUCOSIDE-6ʹʹ-O-ACYLTRANSFERASE(Vv3AT), encodes a BAHD acyltransferase protein (named after the first letter of the first four characterized proteins: BEAT for acetyl CoA:benzylalcohol acetyltransferase, AHCT for anthocyaninO-hydroxycinnamoyltransferase, HCBT for anthranilateN-hydroxycinnamoyl/benzoyltransferase, and DAT for deacetylvindoline 4-O-acetyltransferase), belonging to a clade separate from most anthocyanin acyltransferases. Functional studies (in planta and in vitro) show that Vv3AT has a broad anthocyanin substrate specificity and can also utilize both aliphatic and aromatic acyl donors, a novel activity for this enzyme family found in nature. In cv Pinot Noir, a red-berried grapevine mutant lacking acylated anthocyanins,Vv3ATcontains a nonsense mutation encoding a truncated protein that lacks two motifs required for BAHD protein activity. Promoter activation assays confirm thatVv3ATtranscription is activated by VvMYBA1, which adds to the current understanding of the regulation of the BAHD gene family. The flexibility of Vv3AT to use both classes of acyl donors will be useful in the engineering of anthocyanins in planta or in vitro.
Improving wine composition is a critical factor for the wine industry. Phenolic compounds play an important role in wine composition contributing to its organoleptic characteristics. Although several ...factors can influence the phenolic concentration, plant water status in particular has shown to have a direct impact on the phenolic compounds. It is however complex to quantitate water deficit by plant water status measurements as they depend on the specific site (topography, viticultural management practices and soil characteristics) creating variable values within the vineyard block. This study focused on analysing the effect of natural spatial and temporal variability of plant water status on grape and wine parameters. A field experiment was done in a commercial Cabernet Sauvignon block to monitor the temporal and spatial intra-block variability of plant water status using a grid sample method. Soil analysis and topography were included in the evaluation. Each target vine was assessed for yield, ripeness as well as standard juice parameters. Micro-vinification was done for each target vine and the concentration of anthocyanins and tannins analysed. The results showed that the spatial and temporal variability was evident along the season. Plant water status influenced changes in the concentration of phenolic compounds and grape parameters. The vines in the stressed class were associated with changes in soil texture and topography. These plants presented a moderate increase (6.7%) in sugar content; a significant increase in anthocyanins (22.2%) and tannins (27.5%); and a strong reduction in yield (53.2%) when compared with the non-stressed classes. The results of this study may help to understand and quantify how spatial variability is naturally distributed and its effect on grape and wine parameters.
•Several factors can influence the phenolic concentration in wine; however, water stress has a direct impact.•Plant water status is variable with-in the vineyard block and depend on the specific site conditions.•Temporal and spatial intra-block variability of plant water status was monitored using a grid sample method.•The level of water stress reached by the vines was associated with changes in soil texture, topography, and climatic conditions along the season.•The vines in the stressed class presented a significant increase in sugar content, anthocyanins and tannins and a strong decrease in yield.
Fungi present on grape surface considerably impact grape growth and quality. However, information of the fungal community structures and dynamics on the worldwide cash crop, the Cabernet Sauvignon ...grape, from the budding to ripening stages remains limited. Here, we investigated the succession of fungal communities on Cabernet Sauvignon grapes from an organic vineyard in Xinjiang, China at different developmental stages
via
high-throughput sequencing combined with multivariate data analysis. In total, 439 fungal amplicon sequence variants (ASVs) from six phyla were identified. The fungal communities differed over the budding to the berry stages. Moreover,
Aspergillus
,
Malassezia
,
Metschnikowia
, and
Udeniomyces
were predominant during the unripe stage, whereas
Erysiphe
,
Cryptococcus
,
Vishniacozyma
, and
Cladosporium
were dominant in the ripe stages. Notably,
Vishniacozyma
was the most abundant genus, conserved in all development stages. Moreover, network analysis resulted in 171 edges—96 negative and 75 positive. Moreover, fungal genera such as
Vishniacozyma
,
Sporobolomyces
,
Aspergillus
,
Alternaria
,
Erysiphe
,
Toxicodendron
, and
Metschnikowia
were present in the hubs serving as the main connecting nodes. Extensive mutualistic interactions potentially occur among the fungi on the grape surface. In conclusion, the current study expounded the characteristics of the Cabernet Sauvignon grape fungal community during the plant growth process, and the results provided essential insights into the potential impacts of fungal communities on grape growth and health.
•Descriptive Analysis revealed quality drivers of wines entered in a wine competition.•Hedonic liking and perceived quality correlated positively for experts and consumers.•Liking and perceived ...quality of some consumers segments did not match with wine quality scores.•Wine experts use a framework similar to Descriptive Analysis when evaluating liking and quality of red wines.
A Descriptive Analysis panel, wine experts and consumers evaluated 27 Californian Cabernet Sauvignon wines with varying quality scores. Descriptive Analysis revealed several aroma and flavor descriptors driving quality scores. For all consumer segments as well as the wine experts, hedonic liking was shown to highly correlate to perceived quality, but for some consumers liking and perceived quality was not at all correlated to the quality scores of the wines. Wine experts were able to find significant differences in liking and quality, but did not agree completely with the assigned quality scores from the wine judgment. Wine experts also used a combination of both descriptive and hedonic terms when describing a high quality wine, indicating that they are better at communicating and describing what they like.
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•Cabernet Sauvignon grape was more susceptible to A. carbonarius than Moscato Italico.•Must of Cabernet Sauvignon contained more ochratoxin A than Moscato Italico must.•Higher OTA ...level was verified in Moscato Italico wine than Cabernet Sauvignon.•Higher level of acids and terpenes was found in grape that contained A. carbonarius.•A. carbonarius has not interfered in the antioxidant activity of wines.
Aspergillus carbonarius can produce a possibly carcinogenic mycotoxin named ochratoxin A (OTA). The metabolism of this fungus can also impact grape and wine quality as it influences the volatile and phenolic profiles, which are related to aroma and antioxidant activity, respectively. The objective of this study was to evaluate the effect of A. carbonarius on OTA levels and for the first time on volatile profile and antioxidant activity of grapes and their respective wines. Cabernet Sauvignon (CS, red) grapes presented higher susceptibility to A. carbonarius than Moscato Italico (MI, white) grapes and OTA levels in their respective musts were in accordance with this same trend. However, vinification of red grapes resulted in 67% reduction of OTA, while the reduction observed with white wines was 45%. The presence of acids (hexanoic, octanoic, nonanoic and decanoic, fatty odor) was found to be an indicative of the fungus incidence in grapes. These acids were precursors of esters that might impart negative aroma (methyl nonanoate and isoamyl octanoate, fatty odor) or provide desirable fruity characteristics (ethyl hexanoate, ethyl octanoate and methyl octanoate) for wine. In addition, terpenes were detected only in wines produced with grapes (CS and MI) inoculated with A. carbonarius. The presence of A. carbonarius increased the antioxidant activity of CS grapes. For MI grapes and both wines (CS and MI) no differences were verified in the antioxidant activity of the samples affected or not affected by this fungus. Although A. carbonarius occurrence has shown no influence on the antioxidant activity of wines, it produced OTA and has negatively influenced the wine odor profile, due to the production of some volatiles that impart a deleterious effect on wine aroma.
Dieback symptoms have been increasingly reported in Chilean vineyards over recent years. Although there have been studies on Botryosphaeriaceae species and associated trunk disease incidence and ...severity in table grape-producing vineyards, their impacts on 'Cabernet Sauvignon', the most planted red wine grape in Chile, is unknown. This study determines the fungus species, incidence, disease severity, and yield losses associated with Botryosphaeria dieback in Chilean 'Cabernet Sauvignon' vineyards. Nine vineyards were surveyed during two growing seasons (2010 and 2018), and symptomatic wood samples were taken. Total potential production and yield losses were estimated from spur counts (2010) from harvested vines (2018) with different degrees of infection. Overall disease incidence was 87% in 2010 and 84% in 2018. Severity was 49% in 2010 and 47% in 2018. Yield losses were 39% in 2010 and 46% in 2018. Diplodia seriata was the most prevalent fungus isolated from symptomatic plants in both growing seasons. This study highlights the impacts of grapevine trunk diseases in vineyards in Central Chile, and indicates the need for improved disease management strategies. Keywords. Vitis vinifera, 'Cabernet Sauvignon' disease incidence, disease severity, yield loss.
Cluster thinning (CT) is a common practice to prevent overcropping in viticulture. CT affects vine balance between vegetative and productive growth and further modifies grape composition. This study ...investigated the effects of cluster thinning treatments applied at pea-size stage (CT-AF) and the onset of veraison (CT-V), respectively, on volatile compounds of Cabernet Sauvignon in two seasons (2013–2014). The experimental vineyard was located in the north-west of China with semi-arid and monsoon climate. CT exhibited limited effects on the evolutions of volatile compounds. CT-AF exhibited an inhibition on 6-methyl-5-heptene-2-one accumulation. There were no differences in terpene concentrations between CT-treated and control grapes regardless of CT time. Regarding C6/C9 compounds and their derivatives, CT-AF decreased nonanal concentration whilst CT-V increased (Z)-3-hexen-1-ol concentration. Additionally, there were increases in nonanal, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol and (Z)-3-hexen-1-ol concentrations in grapes with delayed CT. Among benzene derivatives, earlier CT resulted in lower phenol concentrations.
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•Effects of cluster thinning (CT) on volatiles compounds in grapes were evaluated.•CT had limited effects on the evolution of volatile compounds.•CT applied at pea-size stage inhibited 6-methyl-5-heptene-2-one accumulation.•CT modified the concentrations of C6/C9 compounds and their derivatives.•Phenol was negatively responsive to CT applied at pea-size stage.
The pinking phenomenon has been known in the wine world for the past 50 years. The phenomenonoccurs when a white wine turns pink under certain conditions. Since then, a Portuguese study ...foundmalvidin-3-O-glucoside in Siria grapes making a connection to anthocyanin as the causing agent. Control(K), naturally pinked (NP) and pink induced (PI) Sauvignon blanc wine samples were analysed by LCMSand WineScanTM (Fourier Transform Infrared – FTIR) after Solid Phase Extraction. The monomericanthocyanins were analysed by a pH differential method, and CieLab was used to differentiate colourdifferences between the control and pinked samples. It was found that malvidin-3-O-glucoside was belowthe threshold values to facilitate pinking in Sauvignon blanc wines. Petunidin-3-O-glucoside showed aslight peak in the LC-MS analysis, and together with the malvidin-3-O-glucoside, the potential to pinkthe white wines increased. FTIR results showed that phenols and anthocyanins absorption could not bedistinguished and that there were possibly other compounds involved in the pinking of white wines. Analysisby CieLab expressed the PI wines as a darker pink colour than the control wine and the absorbency valueat 500 nm was at least three times higher for PI than the control, showing the aggressive oxidative natureof H2O2 on wine.
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