Plants > Biotechnology / PNTs > Unconfined Release > Decision Documents Decision Document 98-29:
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Designation(s) of the PNT: | MEXP1910IT |
Applicant: | Zeneca Seeds |
Plant Species: | Zea mays L. (corn/maize) |
Novel Trait: | Tolerance to imazethapyr |
Trait Introduction Method: | Mutation breeding |
Proposed Use of PNT's: | Cultivated as a hybrid grain corn for livestock feed and human consumption, not intended to be grown outside the usual production area for corn in Canada. |
Zeneca has developed a corn line which is tolerant to imazethapyr, an imidazolinone herbicide.
Health Canada has determined that food derived from this corn is substantially equivalent to that derived from currently commercialized corn.
Zeneca has submitted data and information on the identity of EXP1910IT corn and characterization of the herbicide tolerance trait. Data from agronomic studies conducted in Canada and data from enzyme activity experiments and proximate analyses were also reviewed.
The Plant Biotechnology Office of the Plant Health and Production Division, with input from the Plant Health Risk Assessment Unit, on behalf of the Science Division, CFIA, has reviewed the information submitted by Zeneca Seeds for the determination of environmental safety based on the following assessment criteria as described in the regulatory directive Dir94-08: Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits:
The Feed Section of the Animal Health and Production Division, CFIA, has also reviewed the information submitted by Zeneca Seeds based on the following assessment criteria for determining safety and efficacy of livestock feed, as described in the regulatory directive Dir95-03: Guidelines for the Assessment of Livestock Feed from Plants with Novel Traits:
The biology of corn (Z. mays), described in Dir94-11, states that unmodified plants of this species are not invasive of unmanaged habitats in Canada. Corn does not possess the potential to become weedy due to traits such as poor seed dormancy, the non-shattering aspect of corn cobs, and poor competitive ability of seedlings. The mutation of the ALS gene in EXP1910IT has not significantly affected the physiology of the plant. It is not expected that EXP1910IT would possess traits that would render it invasive of unmanaged habitats.
No competitive advantage was conferred to EXP1910IT corn other than tolerance to imazethapyr. Corn is an open-pollinated species and EXP1910IT could cross-pollinate with other corn hybrids. The resulting progeny could acquire the herbicide tolerance gene. Progeny from self-pollination will also be imazethapyr tolerant.
Corn volunteers are a common problem in soybean fields when soybeans are cultivated in the year following corn. The imazethapyr herbicide Pursuit® is not registered for the control of corn volunteers per se in soybeans, although phytotoxic effects have been observed when this herbicide is applied on corn. Phytotoxic effects would therefore not be observed in EXP1910IT corn volunteers in a subsequent soybean crop. Corn volunteers are usually at an immature growth stage at soybean harvest time which can cause problems during harvest operations. While this is considered a management problem, it merits consideration and has direct implications for growers.
NOTE: A longer term concern, if there is general adoption of herbicide tolerant crops, is the potential development of crop volunteers with novel tolerances to specific herbicides. This could result in the loss of the use of these herbicides in some crop rotation cycles. Agricultural extension personnel, in both the private and public sectors, should therefore promote careful management practices to growers who use these herbicide tolerant crops.
The above considerations, together with the fact that the novel trait has no intended effects on weediness or invasiveness, lead the CFIA to conclude that EXP1910IT corn does not possess altered weed or invasiveness potential compared to currently commercialized corn.
The biology of corn, as described in Dir94-11, indicates that there are no wild relatives in Canada that can freely hybridize with Z. mays. The CFIA therefore concludes that gene flow from EXP1910IT corn to corn relatives is not possible in Canada.
The novel trait in this plant does not inherently confer to EXP1910IT any potential to become a plant pest and Z. mays is not a plant pest in Canada (Dir94-11). The agronomic characteristics of EXP1910IT were shown to be substantially equivalent to those of the non-mutated hybrid 3751, leading to the conclusion that plant pest potential was unlikely to have been altered.
The mutant ALS gene in this hybrid has not significantly affected the activity of the ALS enzyme. The metabolism of the plant has thus not been altered to unintentionally produce any allergenic or toxic compounds. Based on the above, the CFIA has determined that the unconfined release of EXP1910IT corn, when compared to currently commercialized corn, will not result in significantly impact on interacting organisms, including humans.
EXP1910IT does not possess novel phenotypic characteristics which would extend their use beyond the current geographic range of corn production in Canada. Since corn does not outcross to wild relatives in Canada, there will be no transfer of novel traits to unmanaged environments. The overall relative impact on plant biodiversity is neutral.
No statistically significant differences in nutritional composition, i.e. crude protein, crude fat and crude fibre, were noted between the whole seed of EXP1910IT and those of current commercialized corn cultivars. Valine, isoleucine and leucine contents in whole plants of EXP1910IT were compared to that of its closest counterpart to determine whether the ALS activity of the PNT was affected by the mutation. No statistically significant differences in content of these amino acids were noted. These results collectively demonstrate that the mutation of the ALS gene in EXP1910IT did not result in any observable secondary effects on the composition or nutritional quality of the cultivar. Accordingly, EXP1910IT was judged to be substantially equivalent to traditional corn varieties in terms of nutritional composition.
Based on the review of data and information submitted by Zeneca Seeds, and through comparisons of EXP1910IT with unmodified Z. mays counterparts, the Plant Biotechnology Office of the Plant Health and Production Division, CFIA, has concluded that the novel gene and its corresponding trait do not confer any intended or unintended ecological advantage to EXP1910IT following unconfined release.
Based on the review of data and information submitted by Zeneca Seeds, the Feed Section of the Animal Health and Production Division, CFIA, has concluded that the novel trait does not in itself raise any concerns regarding the safety or nutritional composition of this line. Corn grain and several of its byproducts are currently listed in Schedule IV of the Feeds Regulations and are, therefore, approved for use in livestock feeds in Canada. As whole seeds and plants of EXP1910IT have been assessed and found to be substantially equivalent to traditional corn varieties, EXP1910IT and its byproducts are considered to meet the present ingredient definitions and are approved for use as livestock feed ingredients in Canada.
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This bulletin is published by the Plant Health and Production Division, Canadian Food Inspection Agency. For further information, please contact the Plant Biosafety Office, Plant Health and Production Division or the Feed Section, Animal Health and Production Division at the following address:
Canadian Food Inspection Agency
59 Camelot Drive
Nepean, Ontario K1A 0Y9
Telephone: (613) 225-2342
Facsimile: (613) 228-6629
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