Location: Soybean and Nitrogen Fixation ResearchTitle: Effect of a novel mutation in a Delta 9–Stearoyl-ACP-Desaturase on soybean seed oil composition Author
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2012
Publication Date: 11/1/2012
Citation: Ruddle, P., Whetten, R., Cardinal, A., Upchurch, R.G., Miranda, L.M. 2012. Effect of a novel mutation in a Delta 9–Stearoyl-ACP-Desaturase on soybean seed oil composition. Journal of Theoretical and Applied Genetics. 126:241-249. Interpretive Summary: The food industry in the United States relies mainly on imported palm sources for solid fat applications. Solid fats high in palmitic acid have a negative effect on cholesterol levels and should be avoided to reduce the risk of cardiovascular disease. Soybean seed oil with high stearic acid content would be a healthier alternative because this fatty acid has proven to be cholesterol neutral. Soybean oil typically contains only 2-4% stearic acid. In this research, we report the identification of a novel high stearic mutation that combined with another previously identified gene isoform can increase the stearic acid content in soybean seed to almost 15%. Perfect makers were developed for this mutation and will now be available for other soybean breeding programs across the United States.
Technical Abstract: Soybean [Glycine max (L.) Merr.] oil typically contains 2-4% stearic acid. Seed oil with 20% stearic acid would be useful for solid fat applications, both for its cooking properties and health benefits. Breeding lines with high stearic acid have been developed, but many suffer from agronomic problems. This study: 1) identifies a new source of high stearic acid; 2) determines its relationship with another high stearic locus; and 3) and presents molecular markers for its use in breeding. TCJWB03-806-7-19, a ‘Holladay’ mutant with high stearic acid, was crossed to two FAM94-41-derived lines which contained a point mutation in a seed-specific isoform of a Delta 9–stearoyl-acyl carrier protein-desaturase (SACPD-C). Fatty acid analysis was performed over two growing seasons with F2-derived lines and transgressive segregation for stearic acid content was observed. Sequencing of SACPD isoforms in TCJWB03-806-7-19 revealed the deletion of an ‘A’ nucleotide in exon 3 of SACPD-B which results in a protein whose final 28 amino acids are predicted to differ from Williams82 SACPD-B. Sorting Tolerant From Intolerant (SIFT) analysis revealed that this frameshift mutation may affect SACPD-B protein function. Allele-specific genotyping for the SACPD-C point mutation and SACPD-B nucleotide deletion was performed in both populations. Additive effects and R2 for stearic acid were +3.3 and .55 for SACPD-C and +1.9 and .19 for SACPD-B. Average stearic acid in lines homozygous for both mutations was 14.6%.