Novel food Information: Bromoxynil tolerant canola (Westar-Oxy-235)
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- Development of the modified plant
- Product information
- Dietary exposure
Health Canada has notified Rhône-Poulenc Canada Inc. that it has no objection to the food use of refined oil from the genetically modified canola line designated Westar-Oxy-235, which is resistant to the herbicide bromoxynil. The Department conducted a comprehensive assessment of Westar-Oxy-235 according to its Guidelines for the Safety Assessment of Novel Foods (September 1994). These guidelines are based upon internationally accepted principles for establishing the safety of foods derived from genetically modified organisms.
The following provides a summary regarding the Rhône-Poulenc Canada Inc. notification to Health Canada and contains no confidential business information.
A new variety of canola (Brassica napus) was developed by Rhône-Poulenc Canada Inc. This variety, named Westar-Oxy-235, is tolerant to bromoxynil which controls or suppresses economically important weeds in canola production. It will thus allow farmers the flexibility to use this herbicide after weed problems have been identified, and only when needed.
Development of the modified plant
The development of the bromoxynil-tolerant canola line was accomplished with recombinant DNA technology. A gene (the oxy gene) from a bacterial source (Klebsiella ozaenae) was inserted into a variety of B. napus by disarmed Agrobacterium tumefaciens mediated transformation. The oxy gene expresses an enzyme, nitrilase, that enables the plant to detoxify bromoxynil. No other gene was introduced into the plant.
Molecular analysis of Westar-Oxy-235 plants indicated that a single insertion of the transferred DNA occurred in the B. napus genome, and the integration of the transferred DNA was demonstrated to be stable.
Expression of the oxy gene in Westar-Oxy-235 plants results in the production of the Oxy nitrilase protein in canola tissues. Oxy nitrilase was detected in leaves, stem, roots and, to a lesser extent, in seeds. The amount of enzyme averaged 10 ng/mg total protein in the seeds and 1000 ng/mg total protein in leaves. Analysis demonstrated that the Oxy nitrilase protein could not be detected in the refined oil of Westar-Oxy-235, the only canola product used for human consumption (detection limit 0.2 ng/10 mg of oil, or 20 ppb nitrilase).
The expressed nitrilase enzyme was to be inactivated within five minutes when subjected to simulated gastric fluid diluted to 1/1000, and within 24 hours when subjected to simulated intestinal fluid diluted to 1/1000. The gene nucleotide sequence and the enzyme amino acid sequence were provided and showed no significant homology to toxins or allergens entered into GeneBank or SwissProt databases. This demonstrated that the amino acid sequence of the nitrilase protein did not share similarity with sequences of known toxins or allergens.
Human consumption of canola products is limited to the refined oil. As indicated above (Section 3), the introduced nitrilase enzyme is not detected in the refined oil. As such, no human exposure to the introduced nitrilase protein is expected as a result of consumption of refined canola oil from Westar-Oxy-235.
Comparisons were done using seed harvested from several locations in Canada and in France on the fatty acid composition of Westar (the unmodified canola variety from which the modified line was developed) and Westar-Oxy-235 and the glucosinolate composition of the seeds of these same lines. All the data obtained show that there are no significant differences between the modified and unmodified canola lines tested for these parameters, even after a treatment with bromoxynil. A comparison to literature data equally shows that the genetic modification does not alter the qualitative composition of the genetically modified canola relative to its counterpart. The values obtained are all within the range for canola.
The use of refined oil from Westar-Oxy-235 canola would therefore have no significant impact on the nutritional quality of the Canadian food supply.
Health Canada's review of the information presented in support of the food use of refined oil from bromoxynil tolerant Westar-Oxy-235 concluded that such refined oil does not raise concerns related to safety. Health Canada is of the opinion that refined oil from Westar-Oxy-235 canola is as safe and nutritious as refined oil from current commercial canola varieties.
Health Canada's opinion deals only with the food use of refined oil from the genetically modified canola Westar-Oxy-235. Issues related to growing Westar-Oxy-235 canola in Canada and its use as animal feed are 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 (September 1994).
For further information, please contact:
Novel Foods Section
Health Products and Food Branch
Health Canada, PL2204A1
251 Frederick Banting Driveway
Ottawa, Ontario K1A 0K9
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