Molecular Characterization of the Mutant fap3(A22) Allele for Reduced Palmitate Concentration in Soybean

Abstract

ABSTRACTReduction of the palmitate concentration in soybean [Glycine max (L.) Merr.] oil is desirable for reducing the amount of saturated fat in the human diet. Chemical mutagenesis was used to develop the line A22 with the mutant allele designated fap3(A22) that reduces palmitate concentration in the seed oil. The objective of our study was to determine the molecular basis of the fap3(A22) mutation and develop a corresponding molecular marker to assist in future efforts for developing soybean cultivars with low saturated fat. DNA sequence analysis of the GmFATB1a gene of soybean revealed a single nucleotide polymorphism (SNP) resulting in a nonconservative amino acid substitution that was likely to be detrimental to the function of the 16:0–acyl carrier protein (ACP) thioesterase (TE) enzyme. An association analysis was conducted using F2–derived lines from a cross between the cultivar Archer (Fap3Fap3) and A22 (fap3fap3) that had been analyzed for their palmitate concentration by gas chromatography. Molecular genotyping of these lines established a perfect correlation between lines phenotypically classified as homozygous for the Fap3 allele or homozygous for the fap3(A22) allele based on their palmitate concentration. The polymorphism in the GmFATB1a gene was used to develop a functional, codominant marker that could be used to distinguish the Fap3 and fap3(A22) alleles in segregating populations. This marker will be useful for breeders who are developing low‐saturate cultivars with the fap3(A22) allele.