Total Phenolic Content and Associated Phenotypic Traits in a Diverse Collection of Snap Bean Cultivars

Abstract

Phytochemicals such as phenolic compounds in snap bean (Phaseolus vulgaris) have potential human health benefits. The objectives of this research were to determine the variation in total phenolic content (TPC) measured as gallic acid equivalents (GAEs)—expressed on a fresh weight (FW) basis throughout this study—among a diverse collection of both indeterminate climbing (pole) and determinate (bush) bean cultivars (n = 149) using the Folin–Ciocalteu assay. We also evaluated associations between TPC and phenotypic traits and estimated genotype by environment (G × E) interactions in a subset of the cultivars. The TPC had greater than a 4-fold difference among cultivars and ranged from 0.29 to 1.31 mg·g−1 GAE (mean = 0.49 mg·g−1 GAE). Cultivars were classified into categories of high (≥1.00 mg·g−1 GAE), intermediate (>0.64 to <1.00 mg·g−1 GAE), and low (<0.55 mg·g−1 GAE) TPC. Eighty-four percent, 10%, and 6% of the cultivars fell into the low, intermediate, and high categories, respectively. The pole type cultivars had higher TPC (mean = 0.86 mg·g−1 GAE) when compared with the bush cultivars (mean = 0.47 mg·g−1 GAE). Correlations were observed between TPC and both flower and pod pigmentation. G × E interactions did not occur among pole type cultivars for TPC during 2 years of production, but a significant G × E interaction was observed among bush cultivars. The results demonstrate a wide diversity in snap bean cultivars for TPC, and the pole beans averaged higher TPC than bush bean cultivars. This information should be useful to identify high TPC snap bean cultivars.