THE POTENTIAL RELATIONSHIP OF STILBENE (RESVERATROL) SYNTHESIS TO ANTHOCYANIN CONTENT IN GRAPE BERRY SKINS

The relationship between the production of resveratrol, a phytoalexin related to grape disease resistance, and the anthocyanin content of gr ape berries in diverse Vitis species has been investigated. Previous s tudies have reported that the phytoalexin production potential of grap es suddenly declines at veraison. The results obtained here from assay ing resveratrol and anthocyanins from grape berries in different devel opmental stages suggest that chalcone synthase (EC 2.3.1.74), the key enzyme involved in anthocyanin biosynthesis, may compete with stilbene (resveratrol) synthase (EC 2.3.1.-), such that the decrease of the ab ility of grapes to synthesize resveratrol in response to UV-irradiatio n observed after the onset of fruit ripening may be a consequence of t he concomitant rise of anthocyanin accumulation in fruits.