Tissue-specific Accummulation of Flavonoids in Grape Berries is Related to Transcriptional Expression of VvF3’H and VvF3’5’H

The products and the related gene expression of flavonoid metabolism were examined in the skin and pulp of Yan73 (Vitis 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 VvmybA1 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.