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.