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In grapevine, the anatomy of xylem conduits and the non-structural carbohydrates (NSCs) content of the associated living parenchyma are expected to influence water transport under water limitation. In fact, both NSC and xylem features play a role in plant recovery from drought stress. We evaluated these traits in petioles of Cabernet Sauvignon (CS) and Syrah (SY) cultivars during water stress (WS) and recovery. In CS, the stress response was associated to NSC consumption, supporting the hypothesis that starch mobilization is related to an increased supply of maltose and sucrose, putatively involved in drought stress responses at the xylem level. In contrast, in SY, the WS-induced increase in the latter soluble NSCs was maintained even 2 days after re-watering, suggesting a different pattern of utilization of NSC resources. Interestingly, the anatomical analysis revealed that conduits are constitutively wider in SY in well-watered (WW) plants, and that water stress led to the production of narrower conduits only in this cultivar.

The present study examined the effect of different cap management techniques, maceration length, and ethanol levels through chaptalization on the chemical and sensory composition of Syrah wines from the Edna Valley AVA in California. Punch down wines had significantly higher anthocyanins, tannins, and total polymeric pigments compared to all other treatments. In terms of volatile chemistry, the submerged cap wines tended to have a higher concentration of esters and terpenes compared to the other treatments. Additionally, ethanol levels were more impactful on the chemical composition of the wines. As expected, chaptalized wines had significantly higher ethanol and glucose + fructose levels but also tended to have higher concentrations of esters and terpenes. Sensory evaluation was done through a modification of the Pivot© Profile method using an expert panel of winemakers (n = 15). The results suggested that cap management and the maceration length were more impactful on the sensory profile than the ethanol level whereby each cap management and maceration length treatment had a distinctive profile. As such, the punch down, chaptalized wines showed higher purple hue and color saturation attributes, blueberry orthonasal aromas as well as jammy and black fruit retronasal aromas. Submerged cap wines were associated with significantly meatier orthonasal aromas and reductive retronasal aromas. Extended maceration wines were characterized by more jammy orthonasal aromas and dried fruit retronasal aromas. However, within the extended maceration wines, the effect of chaptalization was apparent whereby the chaptalized wines showed more acetaldehyde aromas while the non-chaptalized wines were characterized by more herbal aromas.

The flavanol composition of red wine, stemming from grape skins and seeds, is a determinant factor of its quality. It has been proposed that the wine flavanol structure depends on the grape cultivar but with skin-derived flavanols prevailing in traditional red winemaking from mature grapes. However, this has not been confirmed for many cultivars. This study analysed the flavanol composition in grapes, wines, and pomace of Syrah, Marselan, and Tannat, Vitis vinifera cultivars known for their potential to yield tannic wines. Across two vintages, 20 wines were produced through traditional winemaking. Flavanols were analysed by HPLC–MS/MS before and after acid-catalysed depolymerisation of proanthocyanidins. Grapes of different ripeness were considered as vineyard with different agronomical characteristics. Nevertheless, each cultivar exhibited a characteristic flavanol composition in both grapes and wines. Notably, all Marselan wines had high proportions of seed-derived flavanols (high proportions of monomers, dimers and low of prodelphinidins), from grapes with high skin flavanol content. In contrast, Tannat and Syrah wines had high proportions of skin-derived flavanols, irrespective of the corresponding seed flavanol levels in grapes. Flavanol extractability from skins mainly regulated wine composition, being unusually low in Marselan, rising with ripeness in Syrah, and consistently high in Tannat, masking the high seed flavanol contents of its grapes. Therefore, wines with high proportions of seed-derived flavanols can be obtained from fermentative macerations of ripe grapes. Pomaces were found to be a rich source of flavanols, primarily from seeds where they largely remain unextractable.

This present study aimed to investigate the recovery of polyphenols from red onion peel (OPP) and pomace of Merlot (MWP) and Syrah (SWP) grape varieties, using a common biphasic solvent (70/30 ethanol/water) and a new biphasic and eco-friendly solvent that has been developed in our laboratory (ethanol of grape origin). Moreover, overnight and ultrasonic-assisted extractions were carried out to investigate whether the extraction method could affect the obtained results. Results showed that 70% ethanol achieved a significantly (p < 0.05) higher yield in total phenolic content (TPC) and total flavonoid content (TFC), while the extracts with ethanol of grape origin exhibited considerably higher antioxidant activity as evidenced by the DPPH and complementary by FRAP assays. The overnight and ultrasonic-assisted extraction played a significant (p < 0.05) role in achieving better extraction of bioactive components such as phenolic compounds. Color parameters were also determined, showing that the presence of yellow, blue and red color tones depend on the extraction method and solvent, due to the different compositional characteristics of pigments, mainly anthocyanins. In addition, physicochemical parameters such as pH and total soluble solids (TSSs) of the extracts were also measured. Finally, the composition of ethanol of grape origin was characterized by means of Ultraviolet–Visible (UV-Vis) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, which confirmed the presence of ethanol and acetic acid. This study brings new results regarding the prospect of using new solvents for the recovery of bioactive compounds from agricultural by-products, and the development direction of scientific research or industrial production, based on ultrasonic-assisted and overnight extraction methods.

The key aroma compounds and the organoleptic quality of two Chinese Syrah wines from the Yunnan Shangri-La region and Ningxia Helan mountain region were characterized. The most important eighty aroma-active compounds were identified by Gas Chromatography-Olfactometry. In both Syrah samples, ethyl 2-methylpropanoate, ethyl 3-methylbutanoate, 3-methylbutyl acetate, 2- and 3-methyl-1-butanol, ethyl hexanoate, ethyl octanoate, 2-phenethyl acetate, methional, 3-methylbutanoic acid, hexanoic acid, octanoic acid, β-damascenone, guaiacol, 2-phenylethanol, trans-whiskylactone, 4-ethylguaiacol, eugenol, 4-ethylphenol, and sotolon were detected to have the highest odor intensities. In the chemical analysis, 72 compounds were quantitated by Stir Bar Sorptive Extraction combined with Gas Chromatography Mass Spectrometry. Based on the Odor Activity Value (OAV), the aromas were reconstituted by combining aroma compounds in the synthetic wine, and sensory descriptive analysis was used to verify the chemical data. Fatty acid ethyl esters, acetate esters, and β-damascenone were found with higher OAVs in the more fruity-smelling sample of Helan Mountain rather than Shangri-La.

This is the first viral metagenomic analysis of grapevine conducted in Mexico. During the summer of 2021, 48 plants displaying virus-like symptoms were sampled in Queretaro, an important grapevine-producing area of Mexico, and analyzed for the presence of viruses via high-throughput sequencing (HTS). The results of HTS were verified by real-time RT-PCR following a standardized testing scheme (Protocol 2010). Fourteen different viruses were identified, including grapevine asteroid mosaic-associated virus (GAMaV), grapevine Cabernet Sauvignon reovirus (GCSV), grapevine fanleaf virus (GFLV), grapevine fleck virus (GFkV), grapevine Pinot gris virus (GPGV), grapevine red globe virus (GRGV), grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine rupestris vein feathering virus (GRVFV), grapevine Syrah virus 1 (GSyV-1), grapevine virus B (GVB), and grapevine leafroll-associated viruses 1, 2, 3, 4 (GLRaV1, 2, 3, 4). Additionally, divergent variants of GLRaV4 and GFkV, and a novel Enamovirus-like virus were discovered. This is the first report of GAMaV, GCSV, GLRaV4, GPGV, GRGV, GRVFV, and GSyV-1 infecting grapevines in Mexico; the impact of these pathogens on production is unknown.

This study focused on the viruses of the Tymoviridae family that infect grapevines in the Czech Republic. Complete sequences of GFkV (grapevine fleck virus) and GRGV (grapevine red globe virus) from the genus Maculavirus and GRVFV (grapevine rupestris vein feathering virus) and GSyV-1 (grapevine Syrah virus 1) from the genus Marafivirus were obtained using high-throughput sequencing of small RNAs and total RNAs. Mixed infections with these viruses were observed, as well as several variants of these viruses in the same plant. Phylogenetic analysis showed the position of the newly obtained virus isolates within the Tymoviridae family. Recombinant analysis provided evidence of single and multiple intraspecific recombinations in GRGV, GSyV-1, and GRVFV. Additionally, GAMaV, a grapevine virus from the genus Marafivirus, was reported for the first time in the Czech Republic.

The effect of maceration time and temperature on the phenolic compounds of Syrah grape musts was studied. Pre-fermentation cold (10 °C) and heat maceration (60, 70 and 80 °C) were applied and compared to traditional maceration (control, 25 °C). The macerations were monitored and the kinetic profile of the maceration was studied by taking samples at 0, 2, 4, 8, 24 and 48 h. The results showed that heat treatment had the most significant effect on the extraction of total polyphenol. A significant loss of anthocyanin content was observed when the maceration was extended beyond eight hours at high temperatures, while longer maceration times seemed to favor the extraction of tannins. A principal component analysis showed that independently of the vinification technique, and for the same grape varieties, different winegrowing regions and harvest years affected the phenolic composition of the grape skin.

Grafting is the most used propagation method in viticulture and is the unique control strategy against Phylloxera. Nevertheless, its practice remains limited mainly due to inconsistent graft success and difficulties in predicting graft compatibility responses of proposed scion–rootstock combinations, slowing down the selection of elite rootstocks. Aiming to identify optimal phenotypic parameters related to graft (in)compatibility, we used four clones of two grapevine cultivars that show different compatibility behavior when grafted onto the same rootstock. Several physiological parameters, internal anatomy of the graft union, chlorophyll fluorescence, and pigment contents of homo- and heterografts were monitored in a nursery-grafting context. The measurements highlighted enhanced performance of the heterografts due to rooting difficulties of Vitis vinifera homografts. This suggests that in viticulture, homografts should only be used as compatibility controls regarding qualitative attributes. By observing the internal anatomy of the union, we found that grapevines might require longer times for graft healing than anticipated. While Affinity Coefficients were not informative to assess incompatibility, leaf chlorophyll concentration analysis proved to be a more sensitive indicator of stress than the analysis of chlorophyll fluorescence. Overall, we conclude that graft take correlated best with callus formation at the graft junction three weeks after grafting.

Cluster thinning is a viticulture tool used to correct overcropping, to improve fruit composition, and to find a balance between shoot growth and berry development. The main purpose of this study was to evaluate the effects of cluster thinning on the wine quality of Syrah cultivar under Mediterranean climate. Particular attention has been given to the volatile aroma compounds which are determinant for the sensory quality of the wine. Manual cluster thinning in the early stage of veraison was applied and compared with a not thinned control. Cluster thinning influenced yield reduction, advanced grape maturity, improved the phenolic content of grapes and therefore of wine, and influenced the volatile profile of wine. The grapes of thinned plants tend to get rich in varietal and fermentation aromas. Despite the economic impact, cluster thinning is a viable option due to the improvement in wine quality, especially for increasing the amount of compounds responsible for the typical aroma and color, at least in the Mediterranean climate where the search was carried out.