Phytoalexin Production Potential of Grape Berries

Abstract

Abstract The capacity to synthesize the stilbene resveratrol in response to UV irradiation is used as a measure of the phytoalexin production potential of grape berry skin. Greenhouse-grown berries after set, but before maturation, had high phytoalexin potential, whereas buds, flowers, and mature fruits had low potential. Stilbenes were not synthesized in the fleshly part of fruit and were found erratically in small amounts in noninduced berry skin. In field samples, ‘Concord’, ‘Cabernet Sauvigon’, and ‘Catawba’ had high resveratrol production potential whereas ‘White Riesling’, ‘Chancellor’, and ‘Cayuga White’ had low potential. The phytoalexin production potential decreased in all cultivars after late August, independent of their maturity.