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Title: A new low linolenic acid allele of GmFAD3A gene in soybean PE1690

item KIM, MINSU - Kyungpook National University
item SONG, JONG TAE - Kyungpook National University
item Bilyeu, Kristin
item LEE, JEONG-DONG - Kyungpook National University

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2015
Publication Date: 8/12/2015
Publication URL:
Citation: Kim, M., Song, J., Bilyeu, K.D., Lee, J. 2015. A new low linolenic acid allele of GmFAD3A gene in soybean PE1690. Molecular Breeding. 35(8):155.

Interpretive Summary: Soybean seed composition affects the value of the seed oil and meal. Due to health concerns over consumption of trans fats, there is a desire to improve the functionality of soybean oil by reducing the polyunsaturated fatty acids in the oil fraction. Previous research has demonstrated the importance of the FAD3A gene in the accumulation of polyunsaturated fatty acids in soybean oil. The objective of this research was to characterize a new source of FAD3A mutant alleles, confirm the effect on polyunsaturated fatty acids, and develop molecular marker assays to enable rapid introgression of the trait into new breeding lines. The mutant line PE1690 contained a splice-site mutation in FAD3A that lowered polyunsaturated fatty acids in soybean oil. The developed molecular marker assay had a perfect assocation with the trait that can be used to breed soybeans that contain more functional oil profiles.

Technical Abstract: Relative fatty acid content of soybean oil is about 12 % palmitic acid, 4 % stearic acid, 23 % oleic acid, 54 % linoleic acid, and 8 % linolenic acid. To improve oxidative stability and quality of oil, breeding programs have mainly focused on reducing saturated fatty acids, increasing oleic acid, and reducing linolenic acid in soybean oil. The objective of this study was to characterize the low linolenic acid trait in seed oil of PE1690, which was derived from an ethyl methane sulfonate-mediated mutagenesis. PE1690 DNA was used to examine the genomic sequence of a candidate gene, and we found a point mutation which substituted guanine to adenine in the second intron splice site of the GmFAD3A gene. Mutation of PE1690 at the first base of the second intron caused missplicing which led to the inclusion of 334 bp of the second intron into the coding sequence. The amino acid sequence of the mutant was analyzed based on cDNA sequence of GmFAD3A in PE1690. The position 128 amino acid, which codes for tryptophan (TGG) in PE1690, was changed to a premature stop codon (TGA). Therefore, the single base mutation in the PE1690 GmFAD3A gene renders the desaturase enzyme nonfunctional. Based on a genetic marker that we developed, the association of the PE1690 derived GmFAD3A allele with linolenic acid level was tested in 89 F2 progeny of a cross between Pungsannamul (wild type) x PE1690. The results showed that the mutation of GmFAD3A in PE1690 was associated with reduced linolenic acid content in the soybean seed oil. A newly developed low linolenic acid soybean PE1690 provides a good genetic resource to improve the quality of soybean oil.