Post-harvest UV-B irradiation induces changes of phenol contents and corresponding biosynthetic gene expression in peaches and nectarines.

In the present study the possibility of enhancing phenolic compound contents in peaches and nectarines by post-harvest irradiation with UV-B was assessed. Fruits of 'Suncrest' and 'Babygold 7' peach and 'Big Top' nectarine cultivars were irradiated with UV-B for 12 h, 24 h and 36 h. Control fruits underwent the same conditions but UV-B lamps were screened by benzophenone-treated polyethylene film. The effectiveness of the UV-B treatment in modulating the concentration of phenolic compounds and the expression of the phenylpropanoid biosynthetic genes, was genotype-dependent. 'Big Top' and 'Suncrest' fruits were affected by increasing health-promoting phenolics whereas in 'Babygold 7' phenolics decreased after UV-B irradiation. A corresponding trend was exhibited by most of tested phenylpropanoid biosynthesis genes. Based on these results UV-B irradiation can be considered a promising technique to increase the health-promoting potential of peach fruits and indirectly to ameliorate the aesthetic value due to the higher anthocyanin content.