Submitted to: Molecular and General Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/29/2000
Publication Date: N/A
Citation: Interpretive Summary: A functional food has physiological benefits beyond nutrition. For example, increased consumption of fruits and vegetables may reduce the risk of heart disease and cancer. Onion has specific sulfur-based compounds that may reduce the risk of heart disease and cancer. We studied the genetics of correlated traits important in the production and use of onion. Carbohydrate content is important for longer storage of onion and may help to prevent certain types of cancer. Pungency is a measure of flavor and consumers in the US generally prefer a less pungent onion. The onion can prevent blood clotting (called antiplatelet activity) and may be important in the prevention of heart attacks or stroke. High Carbohydrate content, strong pungency, and high antiplatelet activity are associated in onion. Using a cross between a highly pungent, high carbohydrate, and high antiplatelet active onion with one low for all three traits, we studied the genetics of these important traits. The same regions of the genome were found to condition all three traits. This means that it will be difficult to develop new onions with relatively low pungency that retain high antiplatelet activity. However, we can combine high antiplatelet activity with higher carbohydrates to potentially reduce the risks of heart disease and cancer. This is the first study of the genetic bases of correlated production, flavor, and health-enhancing attributes in a major vegetable crop. This correlation means that we can produce a health enhancing onion, but it will be highly pungent. It is questioable whether consumers will be willing to eat fresh highly pungent onion.
Technical 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 magnitude of quantitative trait loci (QTL) 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 parent 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.