Genetic Improvement of the Fatty Acid Biosynthesis System to Alter the ω-6/ω-3 Ratio in the Soybean Seed

A high ω-6/ω-3 fatty acid ratio in the soybean seed adversely affects human health. The objective of the present study was to improve the fatty acid biosynthesis to reduce the ω-6/ω-3 ratio by combining the FAD2-1A and FAD2-1B mutant alleles with α-linolenic acid (ω-3) related alleles from wild soybean. The F₂ population comprising 2320 F_2:3 lines developed from S08-14717 × PI 483463 cross exhibited significant variation for fatty acid components. Of these, 114 lines were advanced to the F_5:6 generation and genotyped for FAD2-1A and FAD2-1B alleles. The lines carrying mutant FAD2-1A and FAD2-1B alleles showed ~ 761 g kg⁻¹ oleic, and ~ 50 g kg⁻¹ linoleic acids, which reduced ω-6/ω-3 ratios to ~ 0.6. Conversely, the lines carrying FAD2-1A or FAD2-1B mutant alleles had 267 or 399 g kg⁻¹ oleic, 327 or 471 g kg⁻¹ linoleic, and 120 or 130 g kg⁻¹ α-linolenic acids concentration, respectively. The elevated α-linolenic acid resulted in the reduction of ω-6/ω-3 ratios in the range 2.5–3.9. The present study demonstrated that combining FAD2 mutant alleles with α-linolenic acid-related alleles from wild soybean reduces the seed ω-6/ω-3 ratio.