Mapping Genes Encoding Microsomal ω‐6 Desaturase Enzymes and Their Cosegregation with QTL Affecting Oleate Content in Soybean

Abstract

The microsomal ω‐6 desaturase enzymes, which catalyze the desaturation of oleic acid to linoleic acid during fatty acid biosynthesis, are encoded by the FAD2‐1 and FAD2‐2 genes in soybean [Glycine max (L.) Merr.]. Breeders aim to incorporate the high‐oleate trait into soybean germplasm in order to improve the nutritional value and oxidative stability of soybean oil. The objectives of this study were to map the isoforms of the FAD2‐1 and FAD2‐2 genes and investigate the association of these genetic loci with the oleate phenotype in three populations segregating for oleate content. The populations were grown in replicated multienvironment field trials. According to linkage analysis conducted for two of the populations, FAD2‐1A and FAD2‐1B mapped on Linkage Groups O and I, respectively, while the closely linked FAD2‐2A and FAD2‐2B isoforms mapped on Linkage Group L. Oleate quantitative trait loci with minor effects were detected in the proximity of FAD2‐1B and possibly FAD2‐2B on Linkage Groups I and L. Quantitative trait loci affecting maturity were also detected on chromosomal regions adjacent to the FAD2 genes. The genotyping assays developed for the FAD2‐1A, FAD2‐1B, and FAD2‐2B isoforms, as well as their linked simple sequence repeat markers, can be used in soybean breeding programs for the elevation of oleic acid seed content through marker‐assisted selection.

Soybean Oil: Genetic Approaches for Modification of Functionality and Total Content

“…In the soybean M23 mutant, the mid-oleic acid phenotype is associated with a lesion in one of the FAD2-1 genes (Alt et al, 2005a). However, even under optimal environmental conditions, the M23 genotype and the other mid-oleic acid genotypes require pyramiding of multiple genetic alleles for full penetration of the mid-oleic acid phe- notype (Bachlava et al, 2008b;Monteros et al, 2008). While the factors underlying the yield drag associated with soybean mid-oleic acid mutants is not understood, one plausible explanation is that the fatty acid profile of membranes in vegetative tissues is also altered.…”

Mapping the low palmitate fap1 mutation and validation of its effects in soybean oil and agronomic traits in three soybean populations

“…N98-4445 is a F 3 -derived higholeate (563.1 g kg -1 ), low-linoleate (26.3 g kg -1 ;homozygous for fan PI 123440) line that is a sister line of the released germplasm N98-4445A developed by the USDA-ARS in Raleigh, NC (Burton et al 2006). Satelite is a lowpalmitate (39.8 g kg -1 ; homozygous for fap nc and fap1), low-linolenate cultivar (fan PI 123440) (Cardinal et al 2007;Bachlava et al 2008aBachlava et al , b, 2009bCardinal et al 2011). FAHH00 (F 4 derived lines) was derived from the cross of a high yielding line, 'Corsica' (Kenworthy 1996), and N97-3681-11, a low linolenic (fan PI 123440) and low palmitic acid (homozygous for fap nc and fap1) line.…”

“…DNA isolation was conducted in a 96-well plate format with the Gentra PureGene DNA purification kit (Gentra Systems, Minneapolis, MN). Ninety-eight polymorphic simple sequence repeat (SSR) markers of the consensus linkage map (Cregan et al 1999;Song et al 2004) were genotyped across the 20 linkage groups of the soybean genome in 746 lines of the FAE population following the protocol described by Bachlava et al (2008a). SSR markers very tightly linked to fatty acid candidate genes (GmFAD2-2C, GmFAD2-2D, GmFAD6, GmFAD2-1B, GmAAPT1b) were developed and genotyped as described by Bachlava et al (2009a).…”

Soybean Oil-Quality Variants Identified by Large-Scale Mutagenesis

“…A number of other genes affecting oleate levels are known, but have not been characterized at the molecular level at the time of writing. One possible reason for this is that the dependence of oleic acid levels in soybean seeds upon environmental conditions complicates the molecular mapping of these genes [26][27][28].…”