Five stacked CRISPR edits push a soybean line to 90.2% oleic acid

Two of the five edits account for most of the gain. Conventional soybean oil runs about 20% oleic acid ^[3], and the best edited line reaches 90.2% ^[1]. Of those 70.2 percentage points, the double knockout of GmFAD2-1A and GmFAD2-1B covers 63: it alone took a line to roughly 83% ^{[10] [2]}. The three later edits bought the last 7.2 points ^[2], and they also cut the other two fractions, because FAD2 enzymes convert oleic acid into linoleic acid and FATB enzymes feed saturated fat accumulation ^[7]. In that second round the polyunsaturates fell below 1% each and saturates by more than 40% ^[11].

Five edits were needed because of the crop's history. Soybean has been through genome duplication, so several copies share overlapping functions, and editing one or two of the major genes is often not enough to reach a target composition ^[8]. Lines carrying different combinations of the five edits were grown and evaluated over multiple generations ^[9]. The work appears in the Plant Biotechnology Journal ^[2].

At 90.2% oleic acid with linoleic and linolenic each under 1%, no more than about 7.8 points of the profile are left for everything else, saturates included ^[3]. That ceiling is consistent with the reported cut of more than 40% in saturated fatty acids ^[11].

A second result concerns how much oil the seed holds. Across 805 individual seeds, higher oleic concentration went with higher total fatty acid accumulation ^[13]. The association is correlational, and the expression data do not support the obvious causal path: DGAT and PDAT, which assemble oil directly, were not consistently more active ^[14]. SDP1, which breaks down stored oil during seed maturation, was lower in the high-oleic lines ^[14].

"This study identifies an effective combination of FAD2 and FATB genes for simultaneously increasing oleic acid and reducing oxidation-sensitive and saturated fatty acids," Kim said ^[16]. On what comes next he was explicit: "Following further evaluation of yield and agronomic stability, these materials could support the development of premium edible-oil soybean cultivars and help establish domestic production of high-oleic raw materials" ^[17].

For a processor the appeal is operating cost. The polyunsaturates in conventional oil oxidise, and flavour and quality can degrade during high-temperature processing or long storage ^[4]. Oleic acid resists heat and oxidation, which is why high-oleic oil is credited with a longer frying life and less frequent oil replacement and disposal ^[5]. The team measured seed composition and gene expression on this line ^[4]. The nutritional point applies to fat substitution generally: monounsaturated fat replacing saturated fat in the diet may help lower LDL cholesterol and reduce cardiovascular disease risk ^[6]. The authors note that editing reproduces changes of the kind natural mutation or conventional breeding produces, with no foreign DNA left in the plant ^[18], and they argue that an efficient, science-based approval system that keeps food and environmental safety assessment in place would speed practical use and reduce Korea's dependence on imported high-oleic oil ^[20].