Effect of high temperature on anthocyanin composition and transcription of flavonoid hydroxylase genes in 'Pinot noir' grapes (Vitis vinifera)

Anthocyanin accumulation in grape berry skins is influenced by temperature during the maturation period. Although it has been reported that high temperatures result in lower anthocyanin concentrations in berry skins, their effects on anthocyanin composition remain unclear. To study the effect of high temperature on anthocyanin composition, the accumulation of individual anthocyanins in the skin of 'Pinot noir' berries was investigated in two experiments: Experiment 1, high morning and evening temperature treatment; Experiment 2, high day-time temperature treatment. High temperatures (30 degrees C) in the morning and evening did not the affect the total anthocyanin content in the skin, but decreased the levels of delphinidin 3-glucosides, petunidin 3-glucosides and malvidin 3-glucosides, which are 3',5'-hydroxylated, or methylated following 3',5'-hydroxylation. A high day-time temperature (35 degrees C) also decreased the levels of delphinidin, petunidin and malvidin 3-glucosides. In both Experiments, grape berries grown under high temperature had a low abundance of mRNA for flavonoid 3', 5'-hydroxylase (F3'5'H) in the skin. These results suggest that changes in the accumulation of individual anthocyanins in the skins of 'Pinot noir' grape berries, due to high temperature, are regulated at the level of transcription of the F35'H gene.