Improving the Health Benefits of Snap Bean: Genome-Wide Association Studies of Total Phenolic Content.

James R Myers,Samira Mafi Moghaddam,Henry J Thompson,Lyle T Wallace,Dimas Echeverria,Phillip E Mcclean,Rian Lee,Mark A Brick,Adrienne E Kleintop

doi:10.3390/nu11102509

Abstract

Snap beans are a significant source of micronutrients in the human diet. Among the micronutrients present in snap beans are phenolic compounds with known beneficial effects on human health, potentially via their metabolism by the gut-associated microbiome. The genetic pathways leading to the production of phenolics in snap bean pods remain uncertain. In this study, we quantified the level of total phenolic content (TPC) in the Bean Coordinated Agriculture Program (CAP) snap bean diversity panel of 149 accessions. The panel was characterized spectrophotometrically for phenolic content with a Folin–Ciocalteu colorimetric assay. Flower, seed and pod color were also quantified, as red, purple, yellow and brown colors are associated with anthocyanins and flavonols in common bean. Genotyping was performed through an Illumina Infinium Genechip BARCBEAN6K_3 single nucleotide polymorphism (SNP) array. Genome-Wide Association Studies (GWAS) analysis identified 11 quantitative trait nucleotides (QTN) associated with TPC. An SNP was identified for TPC on Pv07 located near the P gene, which is a major switch in the flavonoid biosynthetic pathway. Candidate genes were identified for seven of the 11 TPC QTN. Five regulatory genes were identified and represent novel sources of variation for exploitation in developing snap beans with higher phenolic levels for greater health benefits to the consumer.

Highlights

The need for transdisciplinary efforts to bridge the gap between production agriculture and public health nutrition is clear [1]
total phenolic content (TPC) ranged from 0.29 to 1.31 mg g−1 gallic acid equivalents (GAE), with the highest levels being associated with colored flowers and pigmented pods
Because anthocyanins are well known for their red-to-blue color, and flavonols are associated with yellow-to-brown pigments, we classified snap bean accessions for flower and seed color as well as obtaining a color profile for pods, in addition to measuring TPC

Summary

Introduction

The need for transdisciplinary efforts to bridge the gap between production agriculture and public health nutrition is clear [1]. Nutrients 2019, 11, 2509 scientists working in horticulture and in human health since horticulture is a science familiar to most consumers and is practiced by many. It is critical for nutritionists to recognize the many factors that are involved in providing consumers with health-beneficial cultivated varieties (cultivars) of a crop and that potential value-added health benefits may result if cultivar-specific food labeling becomes a reality [2,3]. This creates the opportunity for niche markets and for the direct marketing of specific cultivars to the consumer [4,5]. One crop that has received limited attention relative to its health benefits, those related to phenolic compounds, is snap bean (Phaseolus vulgaris L.), which is the topic of this investigation.

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Conclusion