Effect of high CO2 pretreatment on quality, fungal decay and molecular regulation of stilbene phytoalexin biosynthesis in stored table grapes

Table grapes (Vitis vinifera) cv. Cardinal stored at low temperature were analysed to determine the effect of pretreatment with 20 kPa O2 + 20 kPa CO2 + 60 kPa N2 for 3 days on quality and control of decay. The pattern of stilbene synthase (STS) gene expression and trans-resveratrol levels were also analyzed in grapes during low temperature storage at 0 °C and further shelf-life at 20 °C for 2 days. Our results showed that high CO2 pretreatment was effective for improving appearance of the bunches and maintaining the quality of the berries. In CO2-treated bunches the browning and withering index, the decline in relative water content and the weight loss were also lower than in non-treated ones. The levels of STS mRNA and the accumulation of trans-resveratrol in CO2-treated grapes were much lower than in the non-treated grapes during low temperature storage. Moreover, the pattern of STS gene expression and trans-resveratrol content in CO2-treated grapes was consistent with the reduction of natural total decay produced by this pretreatment. This effective non-stressing treatment avoids the induction of trans-resveratrol during low temperature storage until its synthesis is enhanced during shelf-life at 20 °C. © 2006 Elsevier B.V. All rights reserved.Peer Reviewe