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A Novel Allele of GmSACPD-C Associated with High Seed Stearic Acid Concentration in an EMS-Induced Mutant PE980 in Soybean
- Jae-Eun Jeong, Krishnanand P. Kulkarni, Jeong Ho Chang, Bo-Keun Ha, Sung Taeg Kang, Kristin Bilyeu, Hyun Jo, Jong Tae Song, Jeong-Dong Lee
- Crop science 2018 v.58 no.1 pp. 192-203
- adenine, alleles, amino acid sequences, amino acid substitution, exons, genomics, genotyping, guanine, industrial applications, linolenic acid, methionine, mutants, oleic acid, palmitic acid, seed oils, soybeans, stearic acid, valine
- Stearic acid is a relatively minor component of soybean [Glycine max (L.) Merr.] seed oil. Increasing the stearic acid concentration is desired for industrial and food applications, as well as enhanced oxidative stability of the oil. Several ethyl methane sulfonate (EMS)-induced mutants with elevated seed stearic acid concentration have been reported in soybean. Such mutants were often found to carry alterations in the GmSACPD-C gene encoding Δ9-stearoyl-acyl carrier protein-desaturase, the enzyme that catalyzes the conversion of stearic acid to oleic acid in the fatty acid biosynthetic pathway. In the present study, we identified a new GmSACPD-C allele in an EMS-induced high-stearic-acid mutant PE980. The mutant showed a seed stearic acid concentration of ∼160 g kg⁻¹, fourfold that of the wild-type ‘Pungsannamul’. A single base substitution from guanine to adenine at genomic position 703 of first exon of the GmSACPD-C gene was identified through sequencing, and validated by cosegregation analysis of 167 F₂ plants using an allele-specific SimpleProbe marker. The mutation caused a valine to methionine (+70 position) change in the predicted GmSACPD-Cprotein sequence. The sequence alignments and three-dimensional structure modeling of GmSACPD-C showed that the V70M mutation affects substrate binding and dimerization to reduce enzyme activity. Since the mutant showed significant reductions in seed yield compared with the wild type, marker-assisted backcrossing may be needed to reduce the yield gap.