Genetic analyses of correlated solids, flavor, and health-enhancing traits in onion (Allium cepa L.)

Abstract

Onion possesses organosulfur compounds and carbohydrates that provide unique flavor and health-enhancing characteristics. Significant phenotypic correlations have been reported among soluble solids content (SSC), total dry matter, pungency, and onion-induced in vitro antiplatelet activity. A genetic map and segregating F3M families derived from a cross between two inbred populations were used to identify and estimate the effects of quantitative trait loci (QTLs) controlling these traits at 30 and 90 days postharvest. In vitro antiplatelet activities among different onion populations were consistent across six human blood donors. Most of the populations showed in vitro antiplatelet activities; however, for some donors, one of the parental lines and two F3M families had pro-aggregatory effects under our experimental conditions. SSC, dry matter, pungency, and in vitro antiplatelet activity showed significant positive phenotypic and genetic correlations. A chromosome region on linkage group E accounted for a significant amount of the phenotypic variation for all of these traits. The correlations among these traits may be due to linkage or pleiotropy of genes controlling solids content. Our results indicate that it will be difficult to develop onion populations with lower pungency and high in vitro antiplatelet activity; however, the strong genetic and phenotypic correlations between high in vitro antiplatelet activity and high SSC are beneficial for the health functionality of onion.

Relationships among Bioactive Compounds Content and the Antiplatelet and Antioxidant Activities of Six Allium Vegetable Species

“…Antiplatelet activities reported herein of garlic and onion are also comparable with values found for both species in our previous studies using the same in vitro antiplatelet activity procedure (4,7,8,32,33). In these studies, garlic in vitro antiplatelet activity (4,32) was much stronger than that of onion (7,8,33), on fresh mass basis.…”

“…In these studies, garlic in vitro antiplatelet activity (4,32) was much stronger than that of onion (7,8,33), on fresh mass basis. Such differences in in vitro antiplatelet activity between the two species are likely due to their compositional variation, and their bulb water content.…”

“…Sample processing and preparation of aqueous extracts were performed as previously described by Galmarini et al (7). Briefly, the bulb and clove outer dry scales of onion, garlic and shallot were removed and they were cut in quarters longitudinally.…”

“…While most onion cultivars have approx. 90-95 % water (by mass) in their bulbs (7,33), garlic usually has water content in the range of 55-65 % (33). Thus, on fresh mass basis, the antiplatelet compounds in onion are much more diluted than in garlic, and this difference likely reflects part of the observed variation in in vitro antiplatelet activity between the two species.…”

“…Among Allium sp. functional properties that may confer protection against CVD, antiplatelet activity has been extensively studied in garlic (2)(3)(4)(5) and onion (5)(6)(7)(8), and in selected organosulfur compounds from these species (9). Antiplatelet agents have also been found in leek (10) and bunching onion (11).…”