Enhanced Oleic Acid Content in the Soybean Mutant M23 Is Associated with the Deletion in the Fad2‐1a Gene Encoding a Fatty Acid Desaturase

Abstract

Oleic acid is one of the three major unsaturated fatty acids in soybean oil. Expression of the embryo-specific Fad2-1 gene correlates with fatty acid biosynthesis and oil deposition in developing seeds. Elevated levels of oleate in the X-ray-induced mutant line M23 have been shown to be associated with the deletion of a Fad2-1 gene. In soybean, two homologs of the Fad2-1 gene, termed Fad2-1a (L43920) and Fad2-1b (AY611472), presumably encode functional embryo-specific fatty acid desaturase. The objectives of this investigation were to determine which copy of the Fad2-1 gene is associated with the increased oleate content in the mutant line and what is the relative transcript abundance of these two embryo-specific genes. PCR and DNA blot analyses showed that increased oleate content in M23 mutant was associated with the deletion of Fad2-1a. These results were further validated using five independent soybean populations developed by crossing mid-oleate and normal-oleate parents. Investigation of the soybean expressed sequence tag database and reverse transcription PCR analyses revealed that Fad2-1b is the predominantly transcribed copy of the Fad2-1 gene. We hypothesize that null mutation in Fad2-1b in the fad2-1a mutant background should further elevate the oleic contents of soybean oil.Keywords Fad2-1 Á M23 Á Oleic acid Á Oil Á Soybean Electronic supplementary material The online version of this article (

Phenotypic and Genomic Analyses of a Fast Neutron Mutant Population Resource in Soybean

“…Several soybean cultivars with increased oleate content are available, one of which is the midoleate mutant line M23 (Rahman et al, 1994) derived from x-ray mutagenized seed of the Bay soybean cultivar. Genetic studies indicated that the midoleate pheno- type of M23 is associated with the deletion of FAD2-1A (Alt et al, 2005;Sandhu et al, 2007;Anai et al, 2008). Given the agronomic importance of M23 in current breeding programs (Scherder et al, 2008) for increased seed oleate content, CGH could also be utilized to define the presence of other genetic lesions in the M23 genome, in addition to the previously reported FAD2-1A deletion.…”

Combinations of mutant FAD2 and FAD3 genes to produce high oleic acid and low linolenic acid soybean oil

“…The two mutant FAD2-1 alleles (FAD2-1A S117N and FAD2-1B P137R) as well as mutant FAD3A and FAD3C were segregating in this population. The mutant FAD2-1B, FAD3A and FAD3C genes used in this research are identical, while two mutant FAD2-1A alleles were evaluated: the FAD2-1A alleles donated from either M23 (D) or 17D (S117N) (Dierking and Bilyeu 2009;Pham et al 2010;Sandhu et al 2007).…”

“…Naming convention: the combination of four mutant genes: FAD2-1A, FAD2-1B, FAD3A and FAD3C herein is represented as either HO(D)LL4ac or HO(S117N)LL4ac, to distinguish the null FAD2-1A allele donated from either M23 (D) or 17D (S117N) (Dierking and Bilyeu 2009;Sandhu et al 2007). The three mutant gene combination of FAD2-1A, FAD2-1B and FAD3A is designated as HO(D or S117N) LL3a, while the three mutant gene combination of FAD2-1A, FAD2-1B and FAD3C is designated as HO(D or S117N)LL3c.…”

Development of SNP assays associated with oleic acid QTLs in N00-3350 soybean

“…The FAD2-2A gene was closely linked to the FAD2-2B gene on Gm19 (LG-L) (Schlueter et al 2007). The deletion of FAD2-1A was associated with the increased oleic acid content in the mutant line M23 (Sandhu et al 2007). A minor oleate QTL was detected in the proximity of the FAD2-2B gene on Gm19 (LG-L) (Bachlava et al 2008).…”