Polyphenolic Pattern in Apple Tree Leaves in Relation to Scab Resistance. A Preliminary Study

Abstract

Polyphenols were analyzed by HPLC in apple tree leaves of different scab-resistant and -susceptible cultivars to compare their phenolic contents in relation to their resistance to the disease. Quantitative and slight qualitative differences among cultivars were found. Dihydrochalcones (phloridzin and phloretin) and flavonols were the main phenolic compounds determined in all of the cultivars studied. In the younger stage, it would be possible to differentiate sensitive from resistant apple varieties on the basis of their flavanols contents and phloridzin/flavanol ratio. Likewise, higher levels of two p-coumaric acid derivatives were found in cultivars with the polygenic resistance character.