Effects of Temperature on Anthocyanin Biosynthesis in Grape Berry Skins

Although coloration of grape berry skins is influenced by temperature, the details of its effects have not been reported. To find temperature sensitive stages for coloration and to clarify the mechanisms that underlie the effect of temperature on anthocyanin accumulation, two-week treatments at temperatures of 20°C and 30°C were carried out at four different stages of development and ripening using each of three potted vines of Aki Queen (Vitis labrusca x V. vinifera). Anthocyanin accumulation in the skins was significantly higher at 20°C than at 30°C after the temperature treatment, and the most sensitive stage for the temperature treatment was from one to three weeks after coloring began (stage III). Furthermore, at harvest, the grapes treated at 20°C in stage III contained the highest concentration of anthocyanin. After temperature treatment in stage III, the concentration of abscisic acid (ABA), a plant hormone related to anthocyanin accumulation, in the berry skins was 1.6 times higher at 20°C than at 30°C. The copy numbers of accumulated mRNA of anthocyanin biosynthetic enzyme genes and a myb-related regulate gene, VvmybA1, were also higher at 20°C than at 30°C. These results and previous reports indicate that the high and low temperatures during ripening, especially in stage III, likely affect the production and/or degradation of ABA in berry skins and that the endogenous ABA level affects the expression of VvmybA1; the product of VvmybA1 then controls the expression of the anthocyanin biosynthetic enzyme genes.