Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/24/2014
Publication Date: 5/20/2014
Citation: Carrero-Colon, M., Abshire, N., Sweeney, D., Gaskin, E., Hudson, K.A. 2014. Mutations in SACPD-C result in a range of elevated stearic acid concentration in soybean seed. PLoS One. 9(5): e97891. DOI:10.1371/journal.pone.0097891. Interpretive Summary: The soybean seed has valuable and important uses in the production of oils used in biofuels, industrial lubricants, and fats for human consumption. One component of soybean oil is stearic acid, which has several uses, most notably as a baking fat and as a fat which is not associated with increased LDL cholesterol in humans. Normal soybeans contain relatively little stearic acid, and genetically increasing the amount of stearic acid in soybean seeds is a potential way to obtain a healthier oil with expanded utility. This work describes soybean lines which carry a mutant gene which causes them to accumulate up to 3 times the levels of stearic acid found in normal soybean seeds. Identification of the mutation allows breeders to follow the gene and sheds some light on the mechanism of how soybean seeds produce stearic acid. These soybean lines may be used in breeding for improved seed oil composition.
Technical Abstract: Soybean oil has a wide variety of uses, and stearic acid, which is a relatively minor component of soybean oil is increasingly desired for both industrial and food applications. New soybean mutants containing high levels of the saturated fatty acid stearate in seeds were recently identified from a chemically mutagenized population. Six mutants ranged in stearate content from 6-14% stearic acid, which is 1.5 to 3 times the levels contained in wild-type seed of the Williams 82 cultivar. Candidate gene sequencing revealed that all of these lines carried amino acid substitutions in the gene encoding the delta-9-stearoyl-acyl-carrier protein desaturase enzyme (SACPD-C) required for the conversion of stearic acid to oleic acid. Five of these missense mutations were in highly conserved residues clustered around the predicted di-iron center of the SACPD-C enzyme. Co-segregation analysis demonstrated a positive association of the elevated stearate trait with the SACPD-C mutation for three populations. These missense mutations may provide additional alleles that may be used in the development of new soybean cultivars with increased levels of stearic acid.