Comparison of postharvest UV-B and UV-C treatments on table grape: Changes in phenolic compounds and their transcription of biosynthetic genes during storage

The aim of this study was to evaluate the effects of UV-B or UV-C radiation on phenolic compounds and their transcription of biosynthetic genes in table grapes during storage. The table grapes were exposed to each UV treatment at same dose of 3.6 kJ m(-2) and then storage at 4 degrees C for 28 d. The chemical characteristics of grapes, such as total soluble solids, total titratable acidity and pH during storage, were not greatly affected by each UV treatment. The phenolic content and antioxidant activities of grapes after UV-C treatment were always higher than those of the control and UV-B treatment. Individual phenolic compounds were greatly increased during 14 d of storage after UV-B and UV-C treatment especially in UV-C treatment. Several key genes involved in phenylpropanoid, flavonoid and stilbenoid pathways, such as PAL, CHS, F3H, LAR, ANS, STS, were more expressed in response to the UV treatment, particularly in UV-C treatment. It was induced that the postharvest UV-B or UV-C treatments increased the phenolic compounds accumulation of grapes during storage.