Effects of postharvest UV-C irradiation on phenolic acids, flavonoids, and key phenylpropanoid pathway genes in tomato fruit

The possibility of increasing the content of phenolic acids and flavonoids, and inducing the key phenylpropanoid pathway genes in tomato fruit by postharvest UV-C irradiation was assessed. Mature-green tomato fruit were irradiated with UV-C at 4 kJ m(-2) and stored in the dark at 13 degrees C and 95% RH. UV-C irradiation was effective in increasing the total phenolics content and individual phenolic acids and flavonoids, including cafferic acid, p-coumaric acid, trans-ferulic acid, chlorogenic acid, gallic acid, protocatechuic acid, rutin and quercetin. UV-C treatment also induced expression of genes coding for key enzymes in the phenylpropanoid pathway, including PAL, C4H, 4CL, CHS, CHI, F3H and FLS, and enhanced the activities of PAL, C4H, 4CL, CHS and CHI during storage, which in agreement with a corresponding increase in phenolic compounds content. UV-C irradiation resulted in an increase of the content of phenolic acids and flavonoids in tomato fruit during storage.