Analysis of grape secondary metabolites in disease-resistant grape cultivars grown in central Croatia

Abstract

Breeding programs have been launched in the leading wine-growing countries and have been successful since there are multiple new disease-resistant cultivars on the market available to the vine growers. Furthermore, these new cultivars offer substantial reduction in the fungicide use while maintaining high fruit and wine quality. This study investigated the grape secondary metabolites (polyphenolic and volatile organic compounds) in 21 disease-resistant cultivar and compared them to the three widespread vinifera varieties.

White cultivars were subjected to the analysis of volatile organic compounds, and their aroma profiles were compared to Chardonnay. The results revealed high variability among cultivars, with 81 individual compounds analysed. The PCA based on the aroma profiles confirmed this variability, and singled out cultivars Muscaris, Hibernal, and Voltis, which were characterized by high content of terpenes and C13-norisoprenoids. Cultivars that grouped closely to Chardonnay were Souvignier gris, Johanniter, Soreli, indicating similar aroma profile, which was characterized by higher content of alcohols. Polyphenolic profiles were analysed in red cultivars and compared to Merlot and Cabernet Sauvignon. The most distinct differences, as expected, were observed in the anthocyanin profiles. The disease-resistant cultivars showed presence of diglucoside forms of anthocyanins, whereas Merlot and Cabernet Sauvignon were characterized by acylated forms. The PCAbased on the polyphenolic compounds revealed clear separation of vinifera and disease-resistant cultivars, later being characterized by higher concentrations of stilbenes and flavan-3-ols.

These findings affirm the oenological potential and chemotaxonomic distinctiveness of PIWI varieties, supporting their adoption for sustainable production and enhanced disease management in regions vulnerable to fungal pathogens.