Submitted to: Molecular Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/23/2013
Publication Date: 9/24/2013
Citation: Jiang, G., Wang, X., Green, M., Scott, R.A., Hyten, D., Cregan, P.B. 2013. QTL analysis of unsaturated fatty acids in a recombinant inbred population of soybean. Molecular Breeding. 33(2):281-296. Interpretive Summary: The quality of soybean oil is determined by the levels of the five major fatty acids in the oil. Vegetable oils high in oleic and low in linolenic fatty acids are desirable for human consumption and other uses. The objective of this research was to attempt to determine the positions of genes on the soybean chromosomes that affect the levels of these important fatty acids and to find genetic markers that can be used as surrogates to identify soybean breeding lines that produce seeds with a high level of oleic fatty acid and a low level of linolenic fatty acid. 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 oleic and linolenic 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 levels of oleic fatty acid and lower levels of linolenic fatty acid.
Technical Abstract: Soybean [Glycine max (L.) Merr.] is an important oilseed crop which produces around 30% of the world’s edible vegetable oil. The quality of soybean oil is determined by its fatty acid composition. Vegetable oils high in oleic and low in linolenic fatty acids are desirable for human consumption and other uses. The objectives of this study were to identify quantitative trait loci (QTLs) for unsaturated fatty acids, and to evaluate the genetic effects of single QTLs and QTL combinations in soybean. A population of recombinant inbred lines (RILs) derived from the cross of SD02-4-59 × A02-381100 was evaluated for unsaturated fatty acid content in five environments. A total of 516 single nucleotide polymorphism (SNP) markers and 298 simple sequence repeat (SSR) markers which were polymorphic between the parents was used to genotype the mapping population. By using composite interval mapping (CIM) or the interval mapping (IM) method, a total of 26 QTLs for three unsaturated fatty acids were detected in single or multiple environments. Two major QTLs for oleic acid on linkage group E (qOLE-E) and G (qOLE-G-2), two major QTLs for linoleic on linkage group A1 (qLLE-A1-2) and G (qOLE-G-1), and three major QTLs for linolenic on linkage group D1b (qLLN-D1b), F (qLLN-F) and G (qLLN-G) were consistently detected in at least three individual environments and the average data over all environments. Significant QTL × QTL interactions were not detected. However, significant QTL × environment interactions were detected for almost all the QTLs which were repeatedly detected. Some QTLs reported previously were confirmed, and some new QTLs were identified in this study. Comparisons of two-locus and three-locus combinations indicated that cumulative effects of QTLs were significant for all the three unsaturated fatty acids. QTL pyramiding by molecular marker-assisted breeding would be an appropriate strategy for improvement of unsaturated fatty acids in soybean.