ARCHIVED - High Oleic Soybean
Novel Food Information - High Oleic Soybean Event 305423
Health Canada has notified Pioneer Hi-Bred Production Ltd. that it has no objection to the food use of High Oleic Soybean Event 305423. The Department conducted a comprehensive assessment of this soybean event according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of foods with novel traits.
The following provides a summary of the notification from Pioneer Hi-Bred Production Ltd. and the evaluation by Heath Canada and contains no confidential business information.
Soybean event 305423 was genetically modified using recombinant DNA techniques to reintroduce a partial sequence of the soybean microsomal omega-6 desaturase (gm-fad2-1) coding sequence into the genome. The inserted sequence is intended to silence the GM-FAD2-1 enzyme, a seed-specific fatty acid desaturase that converts oleic acid into linoleic acid by the addition of a second double bond at the omega-6 position, in order to generate the high oleic phenotype. Health Canada has previously approved high oleic acid soybean events G94-1, G94-19, and G168 (NF-55) for food use in October, 2000. The high oleic trait found in the above events was also achieved by silencing of the gm-fad2-1 gene. The Department has also approved several low linolenic acid soybean lines for food use (NF-62 on October 17, 2000; and NF-147 on October 5, 2006). However, these soybean lines were selected by conventional plant breeding methods, and do not exhibit the same high oleic fatty acid profiles. Health Canada also previously approved for food use the high oleic acid / low linolenic acid canola lines 45A37 and 46A40 (NF-21) on August 15, 1996. These canola lines are fad-2 gene mutants and exhibit similar oil profiles as the present soybean line.
The assessment conducted by Food Directorate evaluators determined: how soybean event 305423 was developed; how the composition and nutritional quality of soybean event 305423 compared to non-modified varieties; and what the potential is for event 305423 soybeans to be toxic or cause allergic reactions. Pioneer Hi-Bred Production has provided data which demonstrates that event 305423 soybeans are as safe and of the same nutritional quality as traditional soybean varieties used as food in Canada with the exception of significantly higher levels of oleic acid and significantly lower levels of linoleic, linolenic, and palmitic fatty acids.
The Food Program has a legislated responsibility for the pre-market assessment of novel foods and novel food ingredients as detailed in the Food and Drug Regulations (Division 28). Food use of soybean event 305423 is considered novel under the following part of the definition of novel foods:
"c) a food that is derived from a plant, animal or microorganism that has been genetically modified such that
(iii) one or more characteristics of the plant, animal or microorganism no longer fall within the anticipated range for that plant, animal or microorganism."
2. Development of the Modified Plant
Soybean event 305423 was genetically modified using biolistic co-transformation of soybean embryo tissue with two linear DNA fragments: PHP 19340A containing the gm-fad2-1 cassette and PHP17752A containing the gm-hra gene cassette. The gm-fad2-1 cassette is composed of the promoter sequence of the soybean Kunitz trypsin inhibitor gene 3 (P-KTi3), a partial fragment of the soybean microsomal omega-6 desaturase gene (gm-fad2-1), and the terminator sequence of the soybean Kunitz trypsin inhibitor gene 3 (T-KTi3). The gm-hra gene expression cassette is composed of the promoter sequence of soybean S-adenosyl-L-methionine synthetase (P-SAMS), the 5' untranslated region of the soybean SAMS gene (5'UTR-SAMS) flanking an intron (I-SAMS), a modified version of the acetolactate synthase gene from soybean (gm-hra), and the terminator region of the acetolactate synthase gene from soybean (T-als).
Insertion of the partial gm-fad2-1 gene from soybean acts to silence the endogenous gm-fad2-1 gene encoding the GM-FAD2-1 protein. Introduction of the gm-hra gene encodes for the GM-HRA protein, a modified version of a soybean acetolate synthase conferring tolerance to sulfonylurea herbicides. Successfully transformed soybean embryo tissues were selected on media containing sulfonylurea herbicides and a high oleic acid phenotype was detected using a gas chromatography assay.
3. Characterization of the Modified Plant
Southern blot analysis and DNA sequencing of soybean event 305423 demonstrated the presence of four transgene insertions consisting of intact and truncated copies of fragment PHP 19340A. Among the four insertions, a total of eight copies of the KTi3 promoter, seven copies of the gm-fad2-1 fragment, and five copies of the KTi3 terminator are present. Southern blot and sequence analysis have shown that all four inserts were integrated into the soybean genome and that all the above characterized genetic elements are free of further rearrangements. Southern blot analysis and DNA sequencing of soybean event 305423 demonstrated the presence of a single intact copy of fragment PHP 17752A consisting of one copy of the FRT1 recombination site at the 5' end, the SAMS promoter, the SAMS intron and flanking 5'UTR, the gm-hra gene, the als terminator and the FRT1 and FRT6 recombination sites at the 3' end respectively. While a non-functional 495 bp fragment common to the backbone sequences of plasmids PHP17752 and PHP19340 was inserted in the soybean genome, Southern blot and sequence analysis have confirmed the absence of any functional plasmid backbone elements such as the hyg gene conferring resistance to hygromycin and the plasmid origin of replication (ori).
The stability of the inserted gm-fad2-1 cassettes was evaluated from the progeny of three different generations. The results of Southern blot analysis and segregation data demonstrated the stability of the soybean event 305423 at the genomic level.
4. Product Information
Soybean event 305423 differs from its traditional counterpart by the addition of partial sequence of the gm-fad2-1 gene sequence. The inserted sequence silences the expression of endogenous GM-FAD2-1 protein. The loss of expression of GM-FAD2-1 results in the accumulation of oleic acid and a decrease in production of linoleic acid and other downstream polyunsaturated fatty acids in soybean seed. Introduction of the gm-hra gene encodes for the GM-HRA protein, a modified version of a soybean acetolate synthase conferring tolerance to sulfonylurea herbicides.
5. Dietary Exposure
Soybean event 305423 is expected for use in similar applications as other soybean and vegetable oils by the food industry. The intent of this soybean is to produce cooking oil with stable frying qualities that could potentially replace the use of partially hydrogenated vegetable oil shortening. Soy protein isolate is also used in such foods as soups, sauce bases, energy bars, nutritional beverages, infant formula, and dairy replacements. It is estimated that the substitution of high oleic soybean for hydrogenated soybean oil in commercial frying applications would result in a 1.6 g/day increase in oleic acid consumption, a 1.0g day decrease in linoleic acid consumption and a 0.4 g/day reduction in trans-fat consumption.
The nutrient data pertaining to high oleic acid soybean event 305423 were obtained from two studies. The first study compared the nutrient composition of grain derived from the transgenic soybean variety containing event 305423 and a non-transgenic soybean variety with similar genetic background. The second study was conducted to determine the nutrient composition of four commercial non-transgenic soybean varieties in order to generate reference values.
The grain samples were collected from six sites in the United States and Canada and analyzed for proximates, 18 amino acids, 24 fatty acids, 9 minerals, 4 vitamins, 12 isoflavones, 3 oligosaccharides, and 4 secondary metabolites and anti-nutrients.
The chemical and nutritional composition of the soybean from transgenic and non-transgenic samples was comparable with the exception of the intentionally higher oleic acid content. Additionally, linoleic, linolenic and palmitic fatty acid content in the transgenic line were significantly lower compared with the control soy.
The gm-hra gene present in soybean event 305423 was derived from soybean and is a modified version of the endogenous soybean ALS. The coding sequence, gm-hra, was inserted to serve as a selectable marker. The encoded protein, GM-HRA, is not considered likely to be a toxin, based on the absence of acute oral toxicity in mice at doses orders of magnitude greater than the range typically associated with toxic proteins. In addition, the novel protein bears no biologically significant homology to any known mammalian toxin or pharmacological agent.
The GM-HRA protein is not considered likely to be an allergen since it does not share the characteristics of protein that are food allergens. Unlike many food allergens, the novel protein constitutes a negligible amount of the total protein in foods that contain it. The amino acid sequence of the novel protein has no significant homology to any known allergen. The novel protein is rapidly degraded in a simulated gastric fluid and in simulated intestinal fluid systems, as detected by western blot analysis. These results suggest that the novel protein would be digested in the mammalian digestive tract.
In terms of endogenous allergen content, soybean event 305423 is not significantly different from that of a conventional soybean. Evidence from an ELISA inhibition assay demonstrated that protein extracts derived from 305423 exhibit no significant difference compared to a conventional soybean counterpart in their ability to bind IgE present in the pooled sera from soy allergic patients.
Health Canada's review of the information presented in support of the food use of High Oleic Soybean Event 305423 does not raise concerns related to food safety. Health Canada is of the opinion that food derived from 305423 soybeans is as safe and nutritious as food from current commercial soybean varieties.
Health Canada's opinion deals only with the food use of soybean event 305423. Issues related to its use as animal feed have been addressed separately through existing regulatory processes in the Canadian Food Inspection Agency.
This Novel Food Information document has been prepared to summarize the opinion regarding the subject product provided by the Food Directorate, Health Products and Food Branch, Health Canada. This opinion is based upon the comprehensive review of information submitted by the petitioner according to the Guidelines for the Safety Assessment of Novel Foods.
(Également disponible en français)
For further information, please contact:
Office of Food Biotechnology
Health Products and Food Branch
Ottawa, Ontario K1A 0L2
Telephone: (613) 941-5535
Facsimile: (613) 952-6400
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