Toward the authentication of varietal wines by the analysis of grape (Vitis vinifera L.) residual DNA in must and wine using microsatellite markers

In an attempt to develop a technique for the identification of grape cultiv ars in commercial wines, a method for the extraction of DNA from must and e xperimental wines was adapted and optimal PCR conditions for the amplificat ion of this DNA were established. DNA was analyzed during the fermentation process for six cultivars (Chardonnay, Clairette blanche, Grenache noir, Me rlot, Muscat blanc a petits grains, and Syrah). The extractions were perfor med on solid parts in suspension as well as on the aqueous fraction. Expect ed profiles for these cultivars were obtained with DNA extracted from the s olid parts during all of the fermentation process and for the wine. The ana lysis of DNA extracted from aqueous fractions was less reproducible, and mi crosatellite amplifications were obtained only in the case of Clairette bla nche, Merlot, and Syrah wines. Results demonstrate that the purification pr ocess is adequate for the analysis but that the DNA concentration represent s the main limiting factor. Technical improvements of the method are discus sed.