‘Quergold’, a New Cultivar of Hybrid Onion with High Quercetin Glycoside Contents

Abstract

Onions contain polyphenolic flavonoid compounds, especially quercetin glycosides. Quercetin has been reported to exhibit antihypertensive effects on humans, and epidemiological studies reported that the polyphenolic flavonoid intake is inversely associated with cardiovascular disease. Onion is a major source of flavonoid intake. Increasing dietary onion intake would increase flavonoid intake, which may reduce the risk of disease. We developed an onion cultivar containing a high concentration of quercetin, ‘Quergold’, a new long-day onion cultivar. ‘Quergold’ was developed by the National Agriculture and Food Research Organization (NARO) and is a hybrid of ‘OSP-3’ and ‘OPP-5’. The male sterile line ‘OSP-3’ was bred from ‘W404A’ and the male fertile line ‘OPP-5’ was bred from an Australian open-pollinated variety (‘Spearwood late brown’) at NARO in 2002. The yield of ‘Quergold’ was lower than those of ‘Kitamomiji-2000’ and ‘Quer-rich’; however, ‘Quergold’ contained a higher concentration of quercetin (5.4 mg quercetin equivalent (Q)・g⁻¹ DW), compared with ‘Kitamomiji-2000’ (3.2 mg Q・g⁻¹ DW) and ‘Quer-rich’ (3.4 mg Q・g⁻¹ DW). Consumers could increase their intake of quercetin through the addition of ‘Quergold’ onions to their daily diet. In addition, foods containing high concentrations of quercetin may be sold at an increased cost and be used to develop a new marketing strategy for selling agricultural products which aim to improve the quality of life through the diet.