Updated December 9, 2019:
?-3 and ?-6 fatty acids (FAs) are essential FAs to higher animals including humans since all mammals must obtain them through their diets. A target ?-6/?-3 FA ratio of 1:1 to 2:1 is recommended for human nutrition since the balance between ?-6 and ?-3 FA metabolites in the human brain is close to 1:1. Unfortunately, soybean oil typically consists of 55% linoleic acid (LA), a ?-6 FA, 10% ?-linolenic acid (ALA), a ?-3 FA, 18% oleic acid and two saturated FAs, hence ?-6/?-3 FA ratio is about 5.5:1. For human consumption, as well as for animal feed especially for poultry and aquaculture an increase in the ALA content of soybean oil is desired.
The overall goal of this research project is to developing a high ?-3 soybean line using a non-GMO approach to soybean improvement/breeding. For this aim, soybean ?-3 desaturase (FAD3), enzymes responsible for ALA production, are re-introduced back into soybean with a stronger native (soybean) promoter sequences to enhance FAD3 expression in developing seeds. The soybean genome has three copies of FAD3s and we are testing all three active isoforms (FAD3A, 3B and 3C) in soybean to determine which one works best for increasing ALA levels in soybean oil. As seen below, the initial screening in somatic embryos with additional expression of FAD3B and FAD3C are promising. The data from mature seeds are still coming in from numerous genetic improvement attempts and the final conclusion should be made in 4 – 6 months. Following these analyses, the most effective desaturase will be introduced back into the soybean genome with native promoter sequence(s) without any foreign gene sequences. The resulting soybean lines with high ALA/?-3 FA will be crossed into the commercial varieties for field production. Such soybeans should expand the use and value of both soybean oil and meal for U.S. farmers.