Changes in the phytoalexin content of various Vitis spp. in response to ultraviolet C elicitation

The phytoalexin production potential of three American Vitis species and th at of three cultivars of Vitis vinifera were evaluated in response to UV-C irradiation. Time course changes in resveratrol, piceid, epsilon-viniferin, and pterostilbene contents were studied within 3 days after a short UV-C i rradiation. Results show that the two major stilbenes accumulated as a resp onse to UV-C elicitation are resveratrol and epsilon-viniferin, a resveratr ol dehydrodimer, the concentration of both compounds usually reaching quant ities > 100 mu g/g of fresh weight. In contrast, piceid and pterostilbene w ere constantly produced in low quantities. Owing to the results obtained, t he role of stilbene phytoalexins in the resistance of grapevines to disease s is discussed.