ARS | Publication request: CANDIDATE GENES AFFECTING SOLUBLE CARBOHYDRATE CONCENTRATIONS AND HEALTH-ENHANCING ATTRIBUTES OF ONION

Submitted to: Plant Genome Analysis Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 10, 2003
Publication Date: January 15, 2004
Citation: Havey, M.J., Galmarini, C.R., Gokce, A., Henson, C.A. 2004. Candidate genes affecting soluble carbohydrate concentrations and health-enhancing attributes of onion. Plant Genome Analysis Abstracts.

Technical Abstract: Onion bulbs accumulate fructans, a type of soluble dietary fiber associated with lower rates of corectal cancers. Higher fructan concentrations in bulbs are correlated with higher pungency, longer dormancy, and greater onion-induced antiplatelet activity (OIAA). We analyzed replicated field trials of a segregating family for types and concentrations of soluble carbohydrates in onion bulbs 90 days after harvest. Means were adjusted using dry weight as the covariant to reveal highly significant (P<0.001) differences among parents and families for total soluble solids, glucose, fructose, sucrose, and the fructans 1-kestose, neokestose, and (6G,1)-nystose. Fructan concentrations showed significant (P<0.05) phenotypic correlations with each other and with sucrose, pungency, and OIAA. These observations are consistent with the hypothesis that onion bulbs accumulating fructans take up or retain less water, concentrating both the thiosulfinates and soluble carbohydrates. Interval mapping of family means from the covariant analyses revealed regions on linkage groups A, D, and F significantly (LOD > 2.3) affecting fructan concentrations. One region on linkage group D near an acid-invertase gene was significantly (LOD = 3.45) associated with sucrose concentrations. This study reveals that the accumulation of sucrose in stored onion bulbs may allow for the combination of sweeter flavor with significant OIAA.