Novel food information: Glufosinate tolerant cotton event LLCotton25

On this page

• Background
• Introduction
• Development of the modified plant
• Characterization of the modified plant
• Product information
• Dietary exposure
• Nutrition
• Chemistry/toxicology
• Conclusion

Background

Health Canada has notified Bayer CropScience that it has no objection to the food use of cottonseed oil from glufosinate tolerant cotton lines containing event LLCotton25. The Department conducted a comprehensive assessment of this cottonseed oil 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 with novel traits.

The following provides a summary of the notification from Bayer CropScience and the evaluation by Heath Canada and contains no confidential business information.

Introduction

Bayer CropScience has developed cotton (Gossypium hirsutum L.) lines based upon transformation event LibertyLink^® cotton 25 (LLCotton25). Cotton varieties containing this event express the bialaphos resistance (bar) gene which confers tolerance to glufosinate-ammonium herbicides (trade name, Liberty^®). Health Canada has previously indicated no objection to the sale of glufosinate tolerant corn lines DLL25 and DBT418 for human food applications in Canada. Like cotton event LLCotton25, these lines express the bar gene which confers tolerance to glufosinate ammonium.

The safety assessment performed by Food Directorate evaluators was conducted according to Health Canada's Guidelines for the Safety Assessment of Novel Foods. The assessment considered: how cotton event LLCotton25 was developed; how the composition and nutritional quality of oil derived from cotton varieties containing this event compare to the oil of non-modified cotton varieties; and what the potential is for oil derived from lines containing this event to be toxic or cause allergic reactions.

The Food Directorate has a legislated responsibility for pre-market assessment of novel foods and novel food ingredients as detailed in Division 28 of Part B of the Food and Drug Regulations (Novel Foods). Foods derived from cotton lines containing event LLCotton25 are considered novel foods 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

1. the plant, animal or microorganism exhibits characteristics that were not previously observed in that plant, animal or microorganism"

Development of the modified plant

Cotton variety Coker 312 was genetically modified by means of Agrobacterium tumefaciens transformation. The transforming plasmid pGSV71 carried a transfer DNA (T-DNA) sequence comprised of the bar gene cassette. The genetic elements of this cassette include the Cauliflower mosaic virus 35S promoter, the Streptomyces hygroscopicus bar gene, and the nopaline synthase (3'nos) terminator derived from the T-DNA of pTiT37. Agrobacterium-mediated transformation results in the transfer of only the T-DNA sequence of pGSV71 into the plant genome.

Characterization of the modified plant

Southern blot and PCR analysis of cotton lines containing the event LLCotton25 demonstrated the insertion of one copy of the T-DNA of pGSV71 in the cotton genome. Southern blot analysis also demonstrated the integrity of the bar gene and regulatory elements, as well as the absence of plasmid-derived sequences outside of the T-DNA region.

In addition, both the inserted DNA and plant genome flanking DNA were sequenced at the transgene locus. The sequence data confirmed that the inserted DNA consists only of the 35S promoter sequence, the bar gene, and the nopaline synthase terminator sequence.

Stability of the inserted bar gene cassette was evaluated in different cotton genetic backgrounds over multiple generations of conventional breeding at various locations. The results obtained demonstrate the stability of the event LLCotton25 at the genomic level in different environments.

Product information

Cotton event LLCotton25 differs from its traditional counterpart by the addition of the novel bar gene sequence into the genome, and the expression of the PAT protein. The protein encoded by this gene is expressed at different levels throughout the plant tissue and throughout the life of the plant.

Refined cottonseed oil does not contain any detectable protein and consists almost entirely of triglycerides. Only the refined oil from cotton lines containing cotton event LLCotton25 will be available for human consumption.

Dietary exposure

Cottonseed oil derived from cotton lines containing event LLCotton25 is expected to be used by the food industry in applications similar to cottonseed oil derived from other cotton varieties. Food grade cottonseed oil is a common vegetable oil ingredient in many processed human foods.

Nutrition

Cottonseed from cotton lines containing event LLCotton25 was analysed for proximates (moisture, ash, fat, crude fibre, acid detergent fibre, and neutral detergent fibre), amino acids (alanine, arginine, aspartic acid, cystine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, total, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine), fatty acids (including myristic, palmitic, stearic, arachidic, behenic, lignoceric, palmitoleic, oleic, linoleic and linolenic), minerals (calcium, phosphorus, iron, magnesium, potassium and zinc), vitamin E and anti-nutrients (phytic acid, gossypol (free & total), and cyclopropenoid fatty acids). The nutrient data provided demonstrated that the composition of cottonseed from cotton lines containing event LLCotton25 is comparable to cottonseed from its non-transgenic counterpart, Coker 312, and seed from commercial cotton varieties. Refined oil from cottonseed lines containing event LLCotton25 is comparable with commercial cottonseed oil.

Chemistry/toxicology

The potential for toxicity for PAT protein expressed in cotton lines containing event LLCotton25 was considered remote. This conclusion was based on the negligible amount of PAT protein or any other protein in refined cottonseed oil, the absence of demonstrated acute toxicity in mice to intravenously administered PAT protein, the lack of sequence homology between PAT protein and known toxins, PAT protein's rapid digestion in simulated gastric and intestinal fluids, and PAT protein's inability to withstand heat greater than 40^oC. There were no additional health concerns regarding endogenous toxins from the product derived from cotton lines containing event LLCotton25 when compared to its non-transgenic product. The endogenous toxins, cyclopropenoid fatty acids and gossypol, in crude and de-odorized cottonseed oil were demonstrated to be present at identical concentrations whether they were derived from cotton lines containing event LLCotton25 or non-transgenic cotton plants. In both cases, the concentrations of these natural toxins in cottonseed oil are not a human health concern.

The possibility that the PAT protein would be an allergen in cotton lines containing event LLCotton25 was also considered remote. This was based on the negligible amount of protein in cottonseed oil, the lack of sequence homology between PAT protein and known allergens, and PAT protein's rapid digestion in simulated gastric and intestinal fluids. These results combined with the negligible amount of any protein in cottonseed oil and the absence of any case reports in the medical literature on cottonseed oil allergy suggest that cottonseed oil derived from cotton lines containing event LLCotton25 would not pose any greater allergenic risk than non-transgenic cottonseed oil.

At the expected level of consumption, there was no greater concern with this cottonseed oil derived from cotton lines containing event LLCotton25 than the cottonseed oil derived from non-transgenic cotton plants, with respect to its potential for toxicity or allergenicity.

Conclusion

Health Canada's review of the information presented in support of the food use of glufosinate tolerant cotton lines containing event LLCotton25 concluded that the food use of cottonseed oil from cotton lines containing this event does not raise concerns related to safety. Health Canada is of the opinion that cottonseed oil from cotton lines containing event LLCotton25 is as safe and nutritious as oils from current commercial cotton varieties.

Health Canada's opinion deals only with the cottonseed oil food use of glufosinate tolerant cotton lines containing event LLCotton25. 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 (September 1994).

For further information, please contact:

Novel Foods Section
Food Directorate
Health Products and Food Branch
Health Canada, PL2204A1
251 Frederick Banting Driveway
Ottawa, Ontario K1A 0K9
bmh-bdm@hc-sc.gc.ca