Plants > Biotechnology / PNTs > Unconfined Release > Decision Documents Decision Document 98-27:
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Designation(s) of the PNT: | BXNTM cotton lines 10215, 10222, 10224 |
Applicant: | Calgene Inc. |
Plant Species: | Cotton (Gossypium hirsutum L.). |
Novel Traits: | Tolerance to bromoxynil herbicide; kanamycin (antibiotic) resistance. |
Trait Introduction Method: | Agrobacterium tumefaciens-mediated transformation. |
Proposed Use of PNT's: | Production of cotton for fibre, cottonseed and cottonseed meal for livestock feed, and cottonseed oil for human consumption. These materials will be grown outside Canada, in the usual production areas for cotton. Cottonseed and cottonseed meal will be imported into Canada for livestock feed use only. |
Calgene Inc. has developed three cotton lines tolerant to bromoxynil herbicide. These cotton lines, referred to as BXNTM cotton (lines 10215, 10222, and 10224) in the present document express a novel tolerance to bromoxynil herbicide. This novel herbicide tolerance permits the use of bromoxynil in cotton production to control or suppress economically important weeds.
The development of the BXNTM cotton lines was accomplished with recombinant DNA technology, resulting in the insertion of two bacterial genes into the Coker 315 cotton variety. A gene expressing a nitrilase enzyme that enables the plant to transform bromoxynil into non- phytotoxic compounds was introduced, along with a gene conferring resistance to the antibiotic kanamycin. The antibiotic resistance gene is of no agricultural interest but the trait was used to select transformed from non-transformed plants during the development phase.
Field tests for the BXNTM cotton lines took place at 57 locations in 13 states in the United States. The lines have received complete approval for commercialization in the United States. Health Canada has determined that cottonseed oil derived from this cotton is substantially equivalent to that derived from currently commercialized cotton (August 1996.)
Calgene has provided data on the identity of the BXNTM cotton lines, a description of the modification method, data and information on the gene insertion sites, copy numbers and levels of expression in the plant, the role of the inserted genes and regulatory sequences in donor organisms, and full nucleotide sequences. The novel proteins were identified, characterized, and compared to the original bacterial proteins,. Relevant scientific publications were also supplied.
Agronomic characteristics such as yield, plant vigour, growth, morphology, germination and flowering, were compared to those of unmodified cotton counterparts. Stress adaptation was evaluated, including susceptibility to various pathogens. Processing qualities of cotton lint such as micronaire, length, strength and elongation were compared. The modified plant was determined to be not significantly different to the unmodified counterpart.
Data to support the suitability of cottonseed and cottonseed meal from the BXNTM cotton lines as livestock feed was provided. Proximate analyses, including crude protein, crude fat, crude fibre, and ash, were provided. The amino acid composition, and residual oil in the cottonseed meal of the modified and unmodified plants was also provided.
The Feed Section of the Plant Products Division, with input from the Plant Health Risk Division, CFIA and advice from the Plant Biotechnology Section has reviewed the above information. The following assessment criteria, as described in the regulatory directives Dir94- 08 and Dir95-03, were used to determine the suitability as livestock feed and the environmental safety of feed from these plants with novel traits:
Cotton (G. hirsutum) is a member of the family Malvaceae. It is a perennial species cultivated as an annual and grown in the United States, mostly in areas from Virginia southward and westward to California. Cotton is not considered a weed pest in the regions where it is grown. It is not grown in Canada as it is not adapted to environmental conditions found at these latitudes
BXNTM lines have no specific added genes for cold tolerance or winter hibernation; no overwintered plants are possible. No cultivation of these cotton lines in any location in Canada will occur.
The biology of Gossypium hirsutum, described in the submission, shows that unmodified plants of this species are not invasive of unmanaged habitats in Canada. According to the information provided by Calgene Inc. the BXNTM cotton lines were determined not to be different from their unmodified counterparts with regard to their environmental safety.
The pollen is heavy and sticky and cross pollination usually occurs in the presence of insect pollinators (bumble bees and honey bees). Cotton is normally self pollinating and the range of natural crossing among cotton plants is very limited.
Wild species of cotton (G. barbadense and G. tomentosum) occur only in arid parts of the tropics and sub-tropics. There are no wild relatives in Canada that can naturally hybridize with G. hirsutum. The CFIA therefore concludes that gene flow from BXNTM lines to cotton relatives is not possible in Canada.
The intended effects of both novel traits are unrelated to plant pest potential, and cotton is not a plant pest in Canada. In addition, agronomic characteristics of BXNTM lines are similar to those described for currently commercialized cotton varieties.
The CFIA has therefore determined that the BXNTM lines do not display any altered plant pest potential.
The detailed characterization of the novel genes and resulting enzymes, as briefly summarized in Part III of the present document, led to the conclusion that these do not result in altered toxic or allergenic properties. The nitrilase and APH(3')II enzymes are rapidly inactivated in simulated gastric fluids by enzymatic degradation. Raw seeds of the BXNTM lines were shown to be substantially equivalent to conventional cotton varieties for their content of antinutritional factors. Seed protein content, amino acid, fibre, oil and fatty acid compositions fall within the range of those of the unmodified counterparts.
Based on the above, the CFIA has determined that the use of BXNTM lines in livestock feeds will not result in altered impacts on interacting organisms, including humans, when compared to current commercialized cotton varieties.
BXNTM lines have no novel phenotypic characteristics which would extend their use beyond the current geographic range of cotton production into Canada. Since cotton does not outcross to wild relatives in Canada, there will be no transfer of novel traits to unmanaged environments. The CFIA has determined that the BXNTM cotton lines will have no impact on biodiversity.
Cottonseed contains a high number of anti-nutritional factors and raw seed is unsuitable for monogastric animals. Processing serves to lower the levels of endogenous toxins and renders the cottonseed meal suitable for livestock feed. Gossypol and cyclopropenoid fatty acids are naturally present in cotton and are considered to be undesirable, anti-nutritional compounds of concern for food and feed safety. Levels of gossypol and cyclopropenoid fatty acids measured in BXNTM cotton were similar to parental varieties and within the range for cultivated cotton. Gossypol content in the control Coker 315 line and the BXNTM lines was approximately 1% of the whole cottonseed. The natural range is from 0.002-6.64% of whole cottonseed. The average percent of cyclopropenoid fatty acids in cottonseed oil in the BXN cotton lines was 0.71. This value was the same in the controls.
Proximate analysis of seed from the three BXNTM lines and three commercial varieties grown in four U.S. locations was conducted. While there were significant differences in protein and fat among the four locations, there was no effect of line, and no interaction between the locations and the lines, indicating that there were no differences between the BXNTM and control cotton lines.
Seed from the three BXNTM lines was shown to be substantially equivalent to the control commercial varieties in nutrient composition.
Based on the review of data and information submitted by Calgene Inc. and thorough comparisons of the BXNTM cotton lines with unmodified cotton counterparts, the Feed Section of the Plant Products Division has concluded that the novel genes and their corresponding traits do not in themselves raise any concerns regarding the safety or nutritional composition of the BXNTM lines. Cottonseed and cottonseed meal are currently listed in Schedule IV of the Feeds Regulations and are, therefore, approved for use in livestock feeds in Canada. As BXNTM cotton has been assessed and found to be substantially equivalent to traditional cotton varieties, with respect to safety and nutritional quality, BXNTM lines and their products are considered to meet the present ingredient definitions and are approved for use as livestock feed ingredients in Canada. None of the BXNTM cotton lines will be grown in Canada nor can the seed overwinter, therefore the release of the feed (meal or seed) into the environment would have no intended or unintended effect.
Feed use, as cottonseed and meal of the BXNTM cotton lines 10215, 10222 and 10224 is therefore authorized. Also, any Gossypium hirsutum lines derived from them, or resulting from the same transformation events, may be released, provided that: no inter-specific crosses are performed; the intended use is similar; and it is known following thorough characterization that these plants do not display any additional novel traits.
This bulletin is published by the Plant Health and Production Division. For further information, please contact the Plant Biosafety Office or the Feed Section at:
Plant Biosafety Office Plant Health and Production Division Plant Products Directorate 59 Camelot Drive, Nepean Ontario, K1A 0Y9 (613) 225-2342 |
Feed Section Animal Health and Production Division Animal Products Directorate 59 Camelot Drive, Nepean Ontario, K1A 0Y9 (613) 225-2342 |
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