%0 Journal Article %A Alexandra Bonomelli %A Laurence Mercier %A Jérôme Franchel %A Fabienne Baillieul %A Emile Benizri %A Marie-Claude Mauro %T Response of Grapevine Defenses to UV—C Exposure %D 2004 %R 10.5344/ajev.2004.55.1.51 %J American Journal of Enology and Viticulture %P 51-59 %V 55 %N 1 %X The defense potential of a tolerant American Vitis rupestris cultivar (Rupestris du Lot) and a susceptible European Vitis vinifera cultivar (Chardonnay) in response to UV-C irradiation was investigated. The expression of eight defense-related genes coding for enzymes of the phenylpropanoid pathway (phenylalanine ammonia lyase and stilbene synthase), the octadecanoid pathway (lipoxygenase), and pathogenesis-related proteins (class I and III chitinases, ß-1,3-glucanase, class 6 pathogenesis-related protein, and class 10 pathogenesis-related protein) was followed by real-time reverse transcription polymerase chain reaction (RT-PCR). Phenolic compound accumulation was monitored by microscopic observation. Accumulation of resveratrol, a major grapevine phytoalexin, was evaluated by HPLC, and chitinase and ß-1,3-glucanase enzyme activities were measured. Both grapevine species responded to UV-C treatment by enhancement of defense mechanisms. Intensity of some defense responses was correlated with tolerance to diseases, as previously described for stilbene accumulation: the tolerant species responded more intensely to UV-C exposure than the susceptible one. UV-C irradiation is a practical and reproducible method for inducing grapevine defense responses and can be useful in determining the defense potential of grapevine cultivars.Acknowledgments: The authors wish to thank Pr. Jean Guern and Dr. Michel Boulay for critical review of the manuscript. %U https://www.ajevonline.org/content/ajev/55/1/51.full.pdf