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United States Department of Agriculture

Agricultural Research Service

Research Project: ALLIUM, CUCUMIS, AND DAUCUS GERMPLASM ENHANCEMENT, GENETICS, AND BIOCHEMISTRY Title: Genetic Analyses of Soluble Carbohydrate Concentrations in Onion Bulbs

Authors
item Havey, Michael
item Raines, Steven -
item Henson, Cynthia

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2009
Publication Date: November 1, 2009
Citation: Havey, M.J., Raines, S., Henson, C.A. 2009. Genetic Analyses of Carbohydrate Accumulation in Onion. Journal of the American Society for Horticultural Science. 134:618-623.

Interpretive Summary: Fructans are a good source of soluble dietary fiber, accumulate in onion bulbs, and show significant correlations with dry weights and pungency. We estimated the genetic effects and interactions between two chromosome regions associated with higher amounts of fructans in onion bulbs. Fructan concentrations decreased significantly between 30 and 90 days after harvest. One region on chromosome 5 of onion primarily affected bulb dry weight, while one region on chromosome 8 significantly affected both dry weights and fructan concentrations. Regions on chromosomes 5 and 8 were dominant for increased dry weights and fructan concentrations, and these two regions independently contributed to higher amounts of fructans. These results will be of interest to onion breeders interested in increasing the concentrations of health-enhancing fructans in onion.

Technical Abstract: Fructans are the primary soluble carbohydrate in onion (Allium cepa L.) bulbs and show significant correlations with dry weights and pungency. In this research, we estimated the genetic effects and interactions between two chromosome regions associated with higher amounts of soluble carbohydrates in onion bulbs. Two segregating inbred families from BYG15-23 by AC43 were grown in field trials over three years and bulbs were evaluated 30 and 90 days post-harvest for dry weights and soluble carbohydrates. Fructan concentrations decreased significantly between 30 and 90 days after harvest, consistent with loss of bulb dormancy over this period. Dry weights were negatively correlated with fructose and positively correlated with sucrose and fructans. Analyses of variance and interval mapping revealed that one region on chromosome 5 primarily affected bulb dry weight, while one region on chromosome 8 significantly affected both dry weights and fructan concentrations. Regions on chromosomes 5 and 8 from BYG15-23 show dominance for increased DW and/or soluble solids. Interactions between regions on chromosomes 5 and 8 were significant only for sucrose and the fructan neokestose, indicating that these regions independently contribute to higher amounts of soluble carbohydrates. These results indicate that onions with low concentrations of soluble carbohydrates were developed by selecting for relatively few recessively inherited chromosome regions.

Last Modified: 12/22/2014
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