Relations between downy/powdery mildew diseases and some phenolic compounds in Vitis spp.

Abstract

Powdery mildew and downy mildew are among the most important diseases of grapevine. The relationship between thesediseases and phenolic components has become increasingly important in recent years. This study evaluated changes of total phenolics,total antioxidant activity, and phenolic compounds (gallic acid and rutin hydrate) in some Vitis species. Vitis labrusca cultivars orgenotypes, Vitis vinifera cultivars, interspecies hybrids, and a Vitis rotundifolia cultivar’s healthy and infected leaves were examined. Thecontents of healthy material and of samples of plant material infected with both microorganisms (Uncinula necator (Schw.) Burr andPlasmopara viticola (Berk. & M.A. Curtis) Berl & De Toni) were determined. In general, the content of all compounds, except rutinhydrate, increased in infected leaves. After infection with powdery mildew, the increase was particularly significant. The total phenoliccontent rose after infection but varied with the cultivar and species. The highest antioxidant activity (598.96 µM TE/100 g) and totalphenolic levels (2248.27 mg GAE/100 g) were identified in V. vinifera ‘Italia’, which is known to be sensitive to fungal diseases. On theother hand, the highest levels of gallic acid (9.26 mg/100 g) were identified in V. rotundifolia ‘Sugargate’, which is known to be resistantto fungal diseases. The highest levels of rutin hydrate (60.44 mg/100 g) were identified in V. vinifera ‘Red Globe’. There was a significantpositive correlation between total phenolics and total antioxidant after both diseases (0.7556–0.6904).