A research team has increased the oleic acid content in soyabeans by editing the fatty acid desaturase-2 (FAD2) gene, Natural Science News wrote.
Although soyabean oil is widely used, conventional varieties contain a high proportion of linoleic acid, which makes the oil prone to oxidation, according to the 16 February report.
Hydrogenation is often used to improve shelf life, but partial hydrogenation could create trans fats, the report said.
The researchers from Junagadh Agricultural University and Jouf University used the CRISPR/Cas9 gene editing technique to alter the FAD2 gene of Indian soyabean variety, Gujarat Junagadh Soybean-3 (GJS-3).
The FAD2 enzyme controls a step in the production of linoleic acid and reducing its activity leads to an increase in oleic acid levels and a decrease in linoleic acid production.
Oleic acid is a healthier, more stable monounsaturated fat, and increasing its levels in soyabean oil would reduce the need for hydrogenation and improve the nutritional profile of the oil, Natural Science News wrote.
Previous research had identified two versions of the FAD2 gene, FAD2-1A and FAD2-1B, as crucial regulators of oleic acid content in soyabean seeds, the report said.
Naturally-occurring mutations in these genes, including a deletion found in the PI 603452 soyabean line, were shown to lead to higher oleic acid levels.
These mutations served as a starting point for understanding how to manipulate the pathway, the report said.
In the latest study, the researchers designed a guide RNA (sgRNA) to target the FAD2 gene in GJS-3.
The CRISPR/Cas9 system was then introduced into soyabean cells using Agrobacterium-mediated transformation – a common technique for introducing foreign DNA into plants.
Editing the FAD2 gene increased oleic acid content from 22% to 33-34%, reducing linoleic acid levels, the team found.
Out of 22 regenerated plants, over half (57.1%) showed evidence of successful Cas9/sgRNA activity.
Further analysis confirmed that three lines (T3, T7 and T15) had specific single-nucleotide substitutions within the FAD2 gene, indicating that the editing process had worked as intended, with an editing efficiency of 13.63%.
Specifically, these edited lines exhibited a substantial increase in oleic acid content, ranging from 42-45% compared to the 22% found in the original, non-edited GJS-3 plants.
This was accompanied by a corresponding decrease in linoleic acid, from 54% to 30-32%, resulting in a nearly two-fold improvement in the ratio of oleic to linoleic acid.
A significant advantage of this approach was that the resulting plants were transgene-free, the report said.
The Cas9 gene and the sgRNA sequence – the components needed for the editing process – were completely removed from the genome, meaning that these edited lines did not contain any foreign DNA, an important consideration for regulatory approval and consumer acceptance of genetically modified (GM) crops.
The first successful application of CRISPR/Cas9 technology to edit the FAD2 gene in an Indian soyabean cultivar, the study represents the technology’s potential to improve oil quality, oxidative stability and processing efficiency in the oilseed, according to the report.
The findings also built on previous research which had identified key mutations in FAD2 genes and offered a precise method for developing high-oleic acid soyabean varieties, Natural Science News wrote.
