Plant genotype affects total antioxidant capacity and phenolic contents in fruit

Objective We wanted to determine the total antioxidant capacity (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid equivalent antioxidant assay; TEAC) of different species and cultivars (strawberry and apple) and to characterize the TEAC among fruits of the same varieties (peach and apricot) but grafted on different rootstocks. Methods The study was carried out with wild strawberry, six varieties of cultivated strawberry, and five varieties of apple and with apricot and peach grafted on five different rootstocks that are known to induce different plant vigor and fruit qualitative features. The TEAC (considering lipophilic and hydrophilic contributions) was determined for all fruit varieties, and total polyphenol contents were assayed. One-way analysis of variance was used to test differences among fruits and to identify possible correlations of TEAC versus total phenolics. Results The following hierarchy of antioxidant activities was found: wild strawberries much greater-than cultivated strawberries much greater-than kiwifruit = apples = apricots = peaches. Further, differences were found among strawberries with different genotypes and in apricots and peaches grafted from different rootstocks. Conclusions These observations suggest the importance of genotype for determining antioxidant potential and phenolic contents. Variety manipulation may be a powerful tool for modifying antioxidant fruit patterns and contents.