Abstract: The purpose of this study is to investigate the effects of vertical canopy and horizontal canopy on the anthocyanin composition of ‘Moldova’ grapes. Vertical trellis system and pergola were conducted to represent vertical canopy and horizontal canopy for two consecutive years, respectively. The temperature and relative humidity around the clusters of two canopy types were recorded by temperature and humidity recorder from the berry expansion stage. Grapes were picked from 9 to 15 weeks after blossom to quantify individual anthocyanins in the skin by HPLC-MS, and the enzyme activities and their gene expression levels involved in the anthocyanin metabolic pathway were measured as well. Finally, the grape quality of different canopy types was compared. The results showed that compared with vertical canopy, horizontal canopy decreased the proportion of high temperature and humidity fluctuation around the cluster, and improved mature fruit quality. In 2015, reducing sugar content, 100-berry weight, anthocyanin and flavonoids of horizontal canopy grapes increased respectively by 2.39%, 5.48%, 27.11% and 44.89% compared with vertical canopy grapes. In 2016, the contents of total phenols, anthocyanin and flavanols increased respectively by 5.09%, 6.45%, and 13.67% compared with vertical canopy. The relative expression of Vitis vinifera UDP-glucoseflavonoid 3-O-glucosyltransferase (VvUFGT), Vitis vinifera O-methyltransferase (VvOMT), Vitis vinifera polyphenol oxidase (VvPPO) genes in horizontal canopy was significantly upregulated from 11 to 13 weeks after blossom, and the enzyme activities of UFGT, OMT and anthocyanin 5-O-glucosyltransferase (5GT) were maintained at high levels from 13 to 15 weeks. From 9 to 13 weeks after blossom, the relative gene expression and enzyme activities of UFGT, leucoanthocyanin dioxygenase, OMT, 5GT and PPO in vertical canopy grapes showed similar trends. The analysis of individual anthocyanins indicated that 13 of 21 individual anthocyanins detected in horizontal canopy grapes were more abundant than in vertical canopy grapes. Meanwhile, the modification degree of anthocyanin was increased, but the type of anthocyanin did not significantly change.

Key words: micro-environment, anthocyanin, ‘Moldova’ grape