TY - JOUR T1 - Development of Methods for Screening Grapevines for Resistance to Infection by Downy Mildew. II. Resveratrol Production JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 65 LP - 68 DO - 10.5344/ajev.1987.38.1.65 VL - 38 IS - 1 AU - M. Barlass AU - R. M. Miller AU - T. J. Douglas Y1 - 1987/01/01 UR - http://www.ajevonline.org/content/38/1/65.abstract N2 - The production of the phytoalexin precursor resveratrol in grapevines was assessed as a screening procedure for estimating resistance to infection by Plasmopara viticola. Methanolic extracts from uv-irradiated leaf discs were measured spectrophotometrically and analyzed by gas-liquid chromatography (GLC). An absorbance peak shift from 338 nm to 330 nm corresponding to changes in resveratrol production was observed for resistant and tolerant varieties but not for susceptible vines. However, resveratrol production appeared to be highly sensitive to environmental changes, limiting its usefulness as a reproducible screening system. In addition, the technique did not transfer well to in vitro-grown leaves (uv irradiance proving to be highly phytotoxic) nor to young seedlings, which gave equivocal results. ER -