Résumé
NADP/NAD-dependent oxidoreductases are involved in the biosynthesis of volatiles, specially in the interconversion of volatile alcohols and aldehydes. Multiple examples exist in the literature regarding alcohol dehydrogenases for conversion of short-chain aldehydes to alcohol, some terpene alcohols to aldehydes and also for modifications in fruit aroma C6 compound profile by genetic engineering. In the present study, we investigated the effect of alcohol dehydrogenase overexpression on the volatile compounds in grapevine leaves. Compared to control, grapevine plants overexpressing ADH displayed no changes in free volatile compounds, but showed significantly enhanced amounts of glycosidically volatile compounds such as C13 norisoprenoids, monoterpenes and shikimates. Additionally the highest level of ABA was found in transformed grapevine leaves. The results presented here showed for the first time that some links could exist between ADH activity and the synthesis ofseveral glycosidically volatile compounds. C13 norisoprenoids and ABA synthesis involve a carotene dioxygenase tlle activity of which might be enhanced in transformed plants.