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The products and the related gene expression of flavonoid metabolism were examined in the skin and pulp of Yan73 (Vtis vinifera L. cv.) grapes, a teinturier variety cultivated in China, and the data were compared with those in the skin and pulp of Cabernet Sauvignon (Vitis vinifera L. cv.) grapes, a well-known red variety. The results showed that, in comparison with the skins of Cabernet Sauvignon, the skins of Yan73 berries were characterised by fewer types of flavonols and anthocyanins, a higher level of flavonoids, and a much lower percentage of 3'-hydroxylated flavonols. Flavonoid metabolism was also present in the pulp of Yan73, and the percentages of 3'-hydroxylated flavonols and 3'-hydroxylated flavan-3-ols were significantly higher than the percentages of their corresponding 3',5'-hydroxylated forms. Only flavan-3-ols were found in the pulp of Cabernet Sauvignon. The expression of VvmybAl exhibited a co-ordination with the accumulation of anthocyanins in the pulp of the teinturier cultivar, which showed great similarity to that in the skin. A good correlation was found between the expression of VvF3'H and 3'-hydroxylated flavonoids, as well as between the expression of VvF3'5'H and 3',5'-hydroxylated flavonoids in the skin and pulp of the grape berries. It is suggested that tissue-specific accumulation of flavonoids in grape berries is related to the transcriptional expression of VvF3'H and VvF3'5'H.

Proanthocyanidins in grape berries are synthesised mainly before véraison, and very little attention is paid to the evolution of proanthocyanidins (PAs) in grapes from véraison to harvest. The present study focused on the changes of flavan-3-ols with different degrees of polymerisation in grape skins and the difference in proanthocyandin composition of 'Shiraz', 'Cabernet Sauvignon' and 'Marselan' grapes (Vitis vinifera L.). The results show that the content of flavan-3-ols, the percentage of prodelphinidins (%P) and mean degree polymerisation (mDP) found in 'Cabernet Sauvignon' berry skins at post-véraison were higher than those in 'Shiraz' and 'Marselan' skins. Only monomelic, dimeric, trimeric and polymeric flavan-3-ols were detected in the three grape cultivars. Polymers with more than tenfold flavan-3-ol units accounted for a relatively high proportion in grape berry skins, and the content in the three cultivars declined continuously during ripening. Principal component analysis showed that proanthocyanidin content, composition and mDP at grape harvest stage depended strongly on grape cultivar. This study provides some useful information for understanding the accumulation of PAs during berry maturation and this information can be used to improve wine quality.