Jiangfei Meng

The ameliorative effects of exogenous melatonin on grape cuttings under water-deficient stress: antioxidant metabolites, leaf anatomy, and chloroplast morphology

Grapes are an important economic crop and are widely cultivated around the world. Most grapes are grown in arid or semi‐arid regions, and droughts take a heavy toll in grape and wine production areas. Developing effective drought‐resistant cultivation measures is a priority for viticulture. Melatonin, an indoleamine, mediates many physiological processes in plants. Herein, we examined whether exogenously applied melatonin could improve the resistance of wine grape seedlings grown from cuttings to polyethylene glycol‐induced water‐deficient stress. The application of 10% polyethylene glycol (PEG) markedly inhibited the growth of cuttings, caused oxidative stress and damage from H2O2 and O2∙− , and reduced the potential efficiency of Photosystem II and the amount of chlorophyll. Application of melatonin partially alleviated the oxidative injury to cuttings, slowed the decline in the potential efficiency of Photosystem II, and limited the effects on leaf thickness, spongy tissue, and stoma size after application of PEG. Melatonin treatment also helped preserve the internal lamellar system of chloroplasts and alleviated the ultrastructural damage induced by drought stress. This ameliorating effect may be ascribed to the enhanced activity of antioxidant enzymes, increased levels of nonenzymatic antioxidants, and increased amount of osmoprotectants (free proline). We conclude that the application of melatonin to wine grapes is effective in reducing drought stress.

Varietal differences among the phenolic profiles and antioxidant properties of four cultivars of spine grape (Vitis davidii Foex) in Chongyi County (China).

Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide sufficient experimental evidence for the strong antioxidant activity of spine grapes, four cultivars from Chongyi County, China, including three red varieties (Junzi #1, Junzi #2, and Liantang) and one white variety (Baiyu) were evaluated. The Junzi #1 had the highest phenolic content (total phenolic, flavonoids, flavanols, and anthocyanins) and the strongest antioxidant capacity (DPPH radical-scavenging capacity, cupric-reducing capacity and hydroxyl radical-scavenging activity) among the four varieties. HPLC analysis of spine grapes revealed that the (+)-catechin was the most abundant phenolics and the hydroxycinnamic acids were the major phenolic acids in the four varieties. Hierarchical cluster analysis showed that the Junzi #1 belongs to the group with high phenolic content and strong antioxidant power. The results suggest the Junzi #1 has the best health promoting properties, and the higher utilization value and potential for development.

Occurrence and estimation of trans-resveratrol in one-year-old canes from seven major Chinese grape producing regions.

The concentration of trans-resveratrol in 165 grape cane samples from three major grape production regions and four large distribution centers of Chinese wild Vitis species were determined by reversed-phase high-performance liquid chromatography (HPLC). Among the different genotype groups and purpose of uses, cultivars of V. vinifera had much higher amounts of trans-resveratrol than did the cultivars of both V. labrusca or V. labrusca and V. vinifera hybrids, and within the V. vinifera species, significantly higher amounts of trans-resveratrol were found in wine grapes compared to table ones. No significant differences were observed between V. labrusca and its hybrids from crosses with V. vinifera, and between red cultivars and white ones (P < 0.05 or P < 0.01). The contents of trans-resveratrol, as a normal constituent occurring in grape canes, in Chinese wild species of V. amurensis, V. pentagona, and V. davidii from their native habitats were also relatively high.

Effect of Rain-Shelter Cultivation of Vitis vinifera cv. Cabernet Gernischet on the Phenolic Profile of Berry Skins and the Incidence of Grape Diseases

Rain-shelter cultivation is an effective cultural method to prevent rainfall damage during grape harvest and widely applied in the Chinese rainy regions. In this study we investigated the effect of rain-shelter cultivation on grape diseases and phenolic composition in the skins of Vitis vinifera cv. Cabernet Gernischet grape berries through the comparison with open-field cultivation at two vintages (2010 and 2011). The results showed that rain-shelter cultivation reduced the incidence of grape diseases significantly and delayed the maturation of Cabernet Gernischet fruits. With regards to most of the phenolic compounds identified in this study, their content in grape samples under rain-shelter cultivation was decreased compared to those under open-field cultivation. However, rain-shelter cultivation stimulated the accumulation of dihydroquercetin-3-O-rhamnoside in grape skins during grape maturation. These were related with micrometeorological alterations in vineyards by using plastic covering under rain-shelter cultivation. It suggests the rain-shelter cultivation makes possible the cultivation of “Cabernet Gernischet” grapes in an organic production system, for providing a decrease in the incidence of diseases and the dependence on chemical pesticides in the grape and wine industry.

Promoting Effect of Foliage Sprayed Zinc Sulfate on Accumulation of Sugar and Phenolics in Berries of Vitis vinifera cv. Merlot Growing on Zinc Deficient Soil

The effect of foliage sprayed zinc sulfate on berry development of Vitis vinifera cv. Merlot growing on arid zone Zn-deficient soils was investigated over two consecutive seasons, 2013 and 2014. Initial zinc concentration in soil and vines, photosynthesis at three berry developmental stages, berry weight, content of total soluble solids, titratable acidity, phenolics and expression of phenolics biosynthetic pathway genes throughout the stages were measured. Foliage sprayed zinc sulfate showed promoting effects on photosynthesis and berry development of vines and the promotion mainly occurred from veraison to maturation. Zn treatments enhanced the accumulation of total soluble solids, total phenols, flavonoids, flavanols, tannins and anthocyanins in berry skin, decreasing the concentration of titratable acidity. Furthermore, foliage sprayed zinc sulfate could significantly influence the expression of phenolics biosynthetic pathway genes throughout berry development, and the results of expression analysis supported the promotion of Zn treatments on phenolics accumulation. This research is the first comprehensive and detailed study about the effect of foliage sprayed Zn fertilizer on grape berry development, phenolics accumulation and gene expression in berry skin, providing a basis for improving the quality of grape and wine in Zn-deficient areas.

Melatonin treatment of pre-veraison grape berries to increase size and synchronicity of berries and modify wine aroma components.

A comprehensive investigation was carried out to determine the effect of exogenous melatonin treatment of pre-veraison grapes on grape berries and its wines. Two melatonin treatments of pre-veraison grape berries increased the weight of the berries by approximately 6.6%. Meanwhile, this melatonin treatment could be beneficial in the reduction of underripe and overripe fruits and in enhancing the synchronicity of the berries. In addition, there were significant differences in the volatile compound composition between the wine produced from the melatonin-treated berries and the wines made from untreated berries. The wine from melatonin-treated pre-veraison grape berries had stronger fruity, spicy, and sweet sensory properties, compared to the wines made from untreated berries. Prolonging the treatment through repeated applications can enhance these effects and under different seasonal conditions, more pronounced effects on the grape quality and wine properties can be observed.

Influence of Fermentation Method on Phenolics, Antioxidant Capacity, and Volatiles in Blackberry Wines

The influence of the type of fermentation method on phenolics, antioxidant capacity, and volatiles in blackberry wine was studied. Dry blackberry wines made by traditional fermentation (TF) and carbonic maceration fermentation (CMF) were analyzed for total polyphenols, flavanols, flavonoids, anthocyanins, proanthocyanidin, and antioxidant capacity. High-performance liquid chromatography was used for analysis of nonflavonoid phenolics (gallic, benzoic, salicylic, syringic, caffeic, coumaric, and ferulic) and flavonoids (catechin, quercetin, and rutin). Volatiles were detected by gas chromatography-mass spectrometry. The results showed that CMF fermentation afforded higher antioxidant activity and phenolic content, especially individual polyphenolics. The total level of phenolics in the CMF wine was substantially higher than in traditional wines: 2953 mg of gallic acid equivalents (GAE)/L for CMF wine vs. 1647 mg of GAE/L for traditional wine. A total of 53 kinds of volatile compounds were detected. Of these, 35 were detected in traditionally brewed wine and 46 in CMF fermented wine. Thus, CMF wine had a more complement volatile profile. The dominance of fruity and floral odor components derived from ethyl esters of fatty acids resulted in the indistinguishable aroma of TF and CMF wines. But, CMF wine had a more complicated aroma. The present results could complement existing theory on the processing of blackberry wines.

Exogenously applied abscisic acid to Yan73 (V. vinifera) grapes enhances phenolic content and antioxidant capacity of its wine

Yan73 is a ‘teinturier’ red wine variety cultivated in China and widely used in winemaking to strengthen red wine colour. The objective of this study was to evaluate the effect of exogenous abscisic acid (ABA) applied to the grapevine cluster on the antioxidant capacity and phenolic content of the wine made from Yan73. Two hundred mg/l ABA was applied on Yan73 grapevine cluster during veraison. As they mature, these ABA-treated and untreated grape berries were transformed into wines, respectively, and the phenolic content and antioxidant capacity of these wines were compared. The results showed that phenolic content (total phenolics, tannins, flavonoids and anthocyanins) and antioxidant capacity were higher in the wine produced with ABA-treated Yan73 grapes than those in the wine from untreated grapes. Compared to Cabernet Sauvignon wine, Yan73 wine had higher phenolic content and stronger antioxidant capacity. These strongly suggest that exogenously applied ABA to Yan73 grapes can enhance phenolic content and antioxidant capacity of its wine, and Yan73 wine has the higher utilization value and potential for development.

Aroma Characterization of Cabernet Sauvignon Wine from the Plateau of Yunnan (China) with Different Altitudes Using SPME-GC/MS

The aroma characteristics of Cabernet Sauvignon wines from five different altitudes (Xidang-2110, Dari-2249, Jiunongding-2330, Adong-2610, and Jiangpo-2788, respectively) in the plateau of Yunnan (China) were detected by headspace solid phase micro-extraction gas chromatography mass spectrometry. The results showed that the numbers of volatile compounds increased with altitude rising, while the concentration of the total volatiles decreased with the exception of Xidang-2110. Alcohol and esters accounted for more than 97% of the total volatile compounds. Ten out of thirty-six components (22%) identified and quantified in five wines were found at concentrations higher than their corresponding threshold values (OAVs > 1). Ethyl hexanoate, ethyl butyrate, and 1-octen-3-ol were the three most powerful odorants in wine from Xidang-2110; but odor activity values and relative odor contribution of 1-octen-3-ol were higher than ethyl hexanoate and ethyl butyrate in the wines from Dari-2249 and Adong-2610; meanwhile β-damascenone, ethyl hexanoate, and 1-octen-3-ol were the three most powerful odorants in wines from Jiunongding-2330 and Jiangpo-2788.

Influence of shriveling on berry composition and antioxidant activity of Cabernet Sauvignon grapes from Shanxi vineyards

BACKGROUND Berry shrivel (BS), a berry development disorder, appears soon after veraison. It occurs worldwide and affects the quality of grape berries and wine. However, it had not been reported in China until recently. This study aimed to investigate the changes in berry composition and antioxidant activity of Cabernet Sauvignon grapes from Xiangning Valley, Shanxi Province, China, during BS. RESULTS Shrinkage contributed to an increase in the concentration of basic grape ingredients such as sugar and acid. An appropriate degree of shrinkage was apparently helpful in improving the phenolic content and increasing the antioxidant activity, but the berries that continued to shrivel showed a low antioxidant activity. Further, the results indicated distinct differences between the berries harvested from the southern side of the canopy and those harvested from the northern side, presumably due to variations in sunlight exposure. CONCLUSION Moderate BS was beneficial since it increased berry quality and antioxidant activity of Cabernet Sauvignon grapes from Shanxi vineyards.