| The anthocyanins in grapes are responsible for the colour of the corresponding wines, which is an important parameter used to evaluate wine quality. Soil condition and the cultivation conditions decide ‘microenvironment’ for grapevine together. The present study was conducted in demonstrational vineyard of winegrapes, which belonged to Citic Guoan Wine Co., Itd in Manas county, Changji, Xinjiang. In the present study, winegrapes “Cabernet Sauvignon(Vitis vinifera L.V)” sampled at different developmental stages were used as test material. The effects of ‘microenvironment of root domain’, ‘microenvironment of canopy’ and ‘microenvironment of fruiting zone’ on the biosynthesis and accumulation of anthocyanins were investigated under different soil conditions, training systems and sunlight exposure or exclusion of cluster. The present work was designed to gradually explore the best cultivation conditions for winegrapes in the Tianshan Mountains, the wine-producing region of Xinjiang, China. At the same time, the influence of microenvironment of canopy and fruiting zone on genes related anthocyanin synthesis were preliminary studied. The results were shown as follows:(1) Soil is a major reason that leads to the different microenvironment of root domain, and different root domain microenvironment affects the quality of the grapes. The soils with mild water stress(relative soil water content: 60~66%) and less organic matter(organic matter content: 0.41%~1.00%) in Yuanyi farm produced looser clusters, heavier berry skins, higher TSS. The soil conditions of two plots caused the difference of vine status about water and nutrients, grapevines from Yuanyi farm under mild water stress(-24.5 <δ13C<-26), and nitrogen content in fruit fell 13%. The total anthocyanins in the grape skin from Yuanyi farm increased 43% compared with another plot(Guangdong farm). The grapes from the Yuanyi farm had higher levels of 3′5′-substituded, O-methylated and acylated anthocyanins, which represented a positive characteristic conferring more stable pigmentation to the corresponding wine in the future. The results about the anthocyanin concentration in wines from two experimental plots were similar to the previous studies about grape berries. It further confirmed that Yuanyi farm produced "Cabernet Sauvignon" grapes with much better quality in some important aspects of winemaking quality.(2) Training system mainly change the microenvironment of canopy, which affect the quality of the grape berries. Compared with F-MT, grapevines trained to M-VSP improved light transmissivity(5.0~7.3%) and increased the PAR level(41.5~64.5%) in the fruiting zone. The leaves from M-VSP had more powerful growth potential, faster metabolic rate and the excellent ability to utilize weak light. M-VSP not only had the lightest and loosest clusters, but it also showed desired wine-making quality due to the heavier seed weight, skin weight, and contained the most seeds per berry, and higher total soluble solids. The anthocyanin concentration in grape skins from M-VSP increased 48%, but the yield decreased 3.4% when compared with F-MT. The anthocyanin concentration in M-VSP wines increased 37%, then resulted in high color intensity. In the wine-producing region of Tianshan Mountains, M-VSP can be proposed as an excellent training system for improving grape and wine quality.(3) Sunlight exposure treatments have a series of influence on grape fruit composition and quality by increasing PAR of fruit zones. In the region with hot and dry climate, excessive exposure of clusters would cause the degradation of anthocyanins at harvest(the largest drop: 79%). The vintage have a great impact on the anthocyanin compositions and concentrations of grape and wine. Therefore, we should recommend different canopy management according to the climate characteristics of different year. Specifically, in a hotter and drier vintage, partly removing of leaves would improve grape and wine quality. However, in a colder year, all leaves around clusters removing at veraison or after veraison will bring more positive effects on wine color.(4) Sunlight exclusion treatments mainly decreased relative light intensity in fruiting zone(almost similar to the night environment), and the changes of temperature and relative humidity can be neglected. In the wine-producing region of Tianshan Mountains, the basal leaves around clusters had a positive role in the biosynthesis and accumulation of anthocyanins at harvest stage. Taking an artificial shading to clusters before veraison, then returning their nature state at veraison could improve anthocyanin accumulation(increased 26.5%) in grape berries and make better color intensity of wine. All the treatments and control can produce much more 3’5’-substituded and O-methylated anthocyanins in 2013 for its colder climate than the vintage with drier and hotter climate. Combined with the results of sunlight exposure treatment, the recommendation in production: shading clusters before veraison, then conducting different sunlight exposure treatments during ripening stage in accordance with the different climatic conditions in different vintages.(5) The expression levels of Vv CHS2, Vv F3’5’H, Vv F3’H, Vv GST and Vv MYB5 b were up-regulated during veraison by sunlight exposure treatment. Thus, M-VSP and sunlight treatment increased the accumulation of anthocyanin in grape skins. The expression levels of Vv CHS2 and Vv LDOX were down-regulated by sunlight exclusion treatment. Taking an artificial shading(sunlight exclusion) to clusters before veraison, then returning their nature state at veraison could up-regulate the expression levels of Vv DFR, Vv F3’5’H and Vv F3’H. Vv OMT exhibited higher transcript levels in berries from sunlight exclusion treatment and F-MT during grape ripening stage. The effects of microenvironment on anthocyanin biosynthesis coordinately regulated by many genes on the flavonoid pathway in grapevine. The accumulation of anthocyanins was influenced by genes which were on upstream metabolic pathways and genes which participate in vacuolar trafficking and sequestration of anthocyanins. In addition, transcript levels of the regulatory genes: Vv MYBA1 and Vv MYB5 b, involved in anthocyanin synthesis confirmed the stimulation of the structural genes. |
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