Submitted to: Molecular Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/21/2012
Publication Date: 2/10/2012
Citation: Jiang, G., Wang, X., Green, M., Scott, R.A., Hyten, D., Cregan, P.B. 2012. QTL analysis of saturated fatty acids in a population of recombinant inbred lines of soybean. Molecular Breeding. 30:1163-1179. Interpretive Summary: Palmitic and stearic acids are the two predominant saturated fatty acids in soybean oil. Different levels of saturated fatty acids are desired depending upon the uses of the soybean oil. Vegetable oil low in saturated fatty acids is preferred for human consumption; while for industrial applications, soybean oil with higher levels of saturated fatty acids is more suitable. The objectives of this study were to identify genetic factors in soybean that control the level of saturated fatty acids in soybean oil and to discuss the potential of using genetic markers as surrogates to identify soybean breeding lines that carry these genetic factors thereby either increasing or decreasing the levels of the saturated fatty acids via plant breeding. Seeds were harvested from five different field experiments from a set of soybean breeding lines derived from a cross of two soybean lines varying is seed fatty acid levels. The fatty acid levels of the seed oil were determined for each line from each experiment. In addition, the soybean breeding lines were analyzed with single nucleotide polymorphism (SNP) DNA markers as well as with simple sequence repeat (SSR) DNA markers. The analysis of the combined seed fatty acid levels and the DNA marker data detected genes, also referred to as quantitative trait loci (QTL), that appeared to control the levels of palmitic and stearic fatty acids in the seed oil. These DNA markers may serve as tools that soybean breeders can use to identify soybean breeding lines that produce seeds with higher or lower levels of palmitic and stearic fatty acids.
Technical Abstract: Soybean [Glycine max (L.) Merr.] is an important crop which contributes to 57.7% of the world’s oilseed production. Palmitic and stearic acids are two predominant saturated fatty acids in soybean oil. Different levels of saturated fatty acids are desired depending upon the uses of the soybean oil. Vegetable oil low in saturated fatty acids is preferred for human consumption; while for industrial applications, soybean oil with higher levels of saturated fatty acids is more suitable. The objectives of this study were to identify quantitative trait loci (QTLs) for saturated fatty acids, analyze the genetic effects of single QTLs and QTL combinations, and discuss the potential of marker-assisted selection in soybean breeding for modified saturated fatty acid profiles. A population of recombinant inbred lines (RILs) derived from the cross of SD02-4-59 × A02-381100 was grown in five environments and the seed samples from each environment were evaluated for fatty acid content. Genotyping of the population was performed with 516 polymorphic single nucleotide polymorphism (SNP) markers and 298 polymorphic simple repeat sequence (SSR) markers. Eight QTLs for palmitic acid, five QTLs for stearic acid and nine QTLs for total saturated fatty acids were detected by composite interval mapping (CIM) and/or interval mapping (IM), with a high level of consistency or repeatability in multiple environments. Most of these QTLs have not been reported previously, with the exception of qPAL-A1 which confirmed the result of a previous study. Significant QTL × QTL interactions were not detected. However, significant QTL × environment interactions were detected in most cases. Comparisons of two-locus and three-locus combinations indicated that cumulative effects of QTLs were significant for both palmitic and stearic acids. QTL pyramiding by molecular marker-assisted selection would be an appropriate strategy for improvement of saturated fatty acids in soybean.