Research on the meaning of the enzymatic systems (GPI and PGM) as parameters for the definition of varieties ( Vitis sp.): The Italian case of Cabernet franc

Abstract

Several studies carried out at Davis and Conegliano showed that isozyme analysis of the GPI and PGM enzymatic systems agrees with the conventional definition of the variety in ampelography. Differences were reported among varieties but not among biotypes of the same varieties. The only exception recorded was in the population of Cabernet franc in which GPI and PGM reveal two different types (A - the traditional type encountered in France and B - type encountered in the Italian region of Veneto). Further ampelographic, ampelometric, phenological and chemical studies on the polyphenolic and aromatic substances in fruits have shown considerable differences between the two types. Such differences demonstrate that the type B is a different variety and not a clone of Cabernet franc. Preliminary ampelographic analysis and the equality in GPI and PGM patterns lead to the conclusion that the type B very probably is Carmenere. Therefore, the hypothesis of variety discrimination based on the analysis of GPI and PGM is valid and this method is useful to help to characterize the varieties.