Improved soybean oil quality by targeted mutagenesis of the fatty acid desaturase 2 gene family

TLDR

Soybean oil is rich in polyunsaturated fats, often partially hydrogenated to improve shelf life and oxidative stability, but this process generates trans‑fatty acids that pose health risks. The authors used TALENs to introduce targeted mutations in the FAD2‑1A and FAD2‑1B genes, which convert oleic acid to linoleic acid in soybean seeds. Four of 19 TALEN‑transformed lines carried heritable FAD2 mutations, and homozygous mutants showed oleic acid rise to 80 % and linoleic acid drop below 4 %, with some plants lacking the TALEN transgene, illustrating TALENs’ power for rapid crop improvement.

Abstract

Summary Soybean oil is high in polyunsaturated fats and is often partially hydrogenated to increase its shelf life and improve oxidative stability. The trans‐fatty acids produced through hydrogenation pose a health threat. Soybean lines that are low in polyunsaturated fats were generated by introducing mutations in two fatty acid desaturase 2 genes ( FAD 2‐1A and FAD 2‐1B ), which in the seed convert the monounsaturated fat, oleic acid, to the polyunsaturated fat, linoleic acid. Transcription activator‐like effector nucleases ( TALEN s) were engineered to recognize and cleave conserved DNA sequences in both genes. In four of 19 transgenic soybean lines expressing the TALEN s, mutations in FAD 2‐1A and FAD 2‐1B were observed in DNA extracted from leaf tissue; three of the four lines transmitted heritable FAD 2 ‐1 mutations to the next generation. The fatty acid profile of the seed was dramatically changed in plants homozygous for mutations in both FAD 2‐1A and FAD 2‐1B : oleic acid increased from 20% to 80% and linoleic acid decreased from 50% to under 4%. Further, mutant plants were identified that lacked the TALEN transgene and only carried the targeted mutations. The ability to create a valuable trait in a single generation through targeted modification of a gene family demonstrates the power of TALEN s for genome engineering and crop improvement.