GE-FAD3KO Soybeans are transgene-free knock-out lines with mutations in the FAD3A and/or FAD3B and/or FAD3C genes of soybean.
The fatty acid desaturase 3 (FAD3) catalyzes the conversion of linoleic acid to linolenic acid in soybean oil and vegetative tissue. An FAD3 knock-out therefore leads to reduced levels of linolenic acid.
The GE-FAD3KO plants were developed by Agrobacterium rhizogenes-mediated hairy-root transformation of soybean cotyledones with a TALEN T-DNA expression vector to knock-out FAD3. Of the three FAD3 genes present in soybean (FAD3A, B and C) the used TALEN construct predominantly targeted FAD3A, but mutations were also induced in FAD3B.
In all the described GE-FAD3 knock-out lines the TALEN T-DNA construct was segregated away. It was undetectable by PCR.
Demorest et al. (2016) describe the lines Gm184 and Gm183:
The GE-FAD2KO Soybean, another gene edited soybean, was used as starting material for GE-FAD3KO line Gm183 . Homogenous mutations ranging from 4 to 43 bp frameshift-inducing deletions were introduced in the FAD3A gene of the GE-FAD2KO Soybean, resulting in a fad2-1a fad2-1b fad3-a knock-out line. In addition to the elevated oleic acid levels of the GE-FAD2KO Soybean, the oil from line Gm183 also has reduced levels of linolenic acid.
For GE-FAD3KO line Gm184 the soybean variety Bert was used as starting material and a homogenous 4 bp frameshift-inducing deletion was introduced in the FAD3A gene. The oil from this line has reduced levels of linolenic acid.
The 2016 “Am I regulated” Inquiry of the company Cellectis for FAD3KO Soybean is less specific with regard to the specific line, but the Inquiry states that plants with mutations in both FAD3A and FAD3B were produced.
Sources:
Demorest et al. (2016) BMC Plant Biol 16:225;
Patent WO2017134601A1;
Am I regulated Inquiry, Cellectis, March 12 2015.