Evaluation of clonal variability of phenolic compounds in Vitis vinifera L. cv. Trnjak crni grown in Croatia

Abstract

Context and purpose of the study. Croatia has rich grapevine genetic resources with more than 130 native varieties preserved. Coastal region of Croatia, Dalmatia, is well known for grape and wine production based on native grapevine varieties. Nevertheless, only a few of varieties play major role on Croatian wine map. In the last three decades, large efforts were made in preservation and revitalization of native grapevine varieties in Croatia. One of the main problems is a lack of certified planting material. Despite the enormous efforts till today, only 16 varieties are involved in the process of clonal selection. Clonal selection is one of the finest tools for preservation, control virus diseases and targeted selection within a certain gene pool.

Material and methods. Clonal selection of Trnjak cultivar resulted in 22 clone candidates, which were planted in experimental vineyard in Imotski winegrowing area, Dalmatia. The evaluation of clone candidates included agronomic and ampelographic parameters, among which polyphenolic profiles were also included. Polyphenolic compounds, as secondary metabolites, are significant factors in the red grape quality. Grapes were collected at full maturity, collecting ten randomly chosen clusters. The analysis of individual polyphenolic compounds was performed by HPLC, and it included anthocyanins, flavonol-glycosides, phenolic acids, stilbenes, and flavan-3-ols.

Results. The clone candidates differed significantly in the content of all analyzed groups of polyphenolic compounds. Clone candidates TRN19, TRN15 and TRN34 were characterized by high concentration of anthocyanins and flavonol-glycosides, while TRN53, TRN70 and TRN112 were characterized by high concentration of flavan-3-ols and phenolic acids. Clone candidates that had significantly low concentrations of analyzed polyphenolic compounds were TRN11, TRN48, TRN118 and TRN71. These results show the high variability in the content of secondary metabolites and the importance of investigating the clonal variation in metabolomics.