Induction of Resveratrol Biosynthesis in Skins of Three Grape Cultivars by Ultraviolet Irradiation

Abstract

Resveratrol production and expression of the genes related to resveratrol biosynthesis were investigated in the skins of three Vitis vinifera cultivars Chardonnay, Koshu and an American hybrid grape, Muscat Bailey A (Bailey × Muscat Hamburg). Resveratrol concentration in the skins of all the grapes increased significantly when exposed to ultraviolet (UV-C, 254 nm) irradiation. The UV-induced resveratrol concentration in the grape skins was lower after veraison (onset of ripening) than before it. The maximum concentration of the UV-induced resveratrol in 'Muscat Bailey A' was higher than those in the other two cultivars. The relative mRNA expression levels of stilbene synthase (STS), phenylalanine ammonia-lyase (PAL) and chalcone synthase (CMS) genes in grape skins 8 hr after UV irradiation were determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results revealed that STS- and PAL-mRNA expressions were significantly increased by UV irradiation. STS-mRNA expressions in 'Muscat Bailey A' were higher than those in 'Chardonnay' throughout berry development. The UV-induced CMS-mRNA expression in the grape skins decreased before veraison and subsequently increased.