Accumulation of flavanols and expression of leucoanthocyanidin reductase induced by postharvest UV-C irradiation in grape berry

To examine the effect of postharvest ultraviolet C (UV-C) irradiation on flavanol polyphenol accumulation in the grape berry, we investigated total flavanol polyphenol content, the enzyme activity of leucoanthocyanidin reductase (LAR), and transcription of Vv lar1 and Vv lar2 using spectrophotometry, real-time polymerase chain reaction, and western blot analysis in 5-year-old Vitis vinifera L. cv. Cabernet Sauvignon plants. Our results indicated that the accumulation of flavanol polyphenol reached its highest value when exposed to UV-C irradiation for 30 min. Additionally, UV-C irradiation induced the transcription of Vv lar1 and Vv lar2 and the synthesis of LAR1 and LAR2 proteins, resulting in increased accumulation of flavanol polyphenol in the grape berry. Moreover, these effects were associated with the length of time of UV-C irradiation.