Database Product Description
- Host Organism
- Gossypium hirsutum (Cotton)
- Trade Name
- Roundup Ready®
- Glyphosate herbicide tolerance.
- Trait Introduction
- Agrobacterium tumefaciens-mediated plant transformation.
- Proposed Use
Production for fibre, livestock feed, and human consumption.
- Product Developer
- Monsanto Company
Summary of Regulatory Approvals
Summary of Introduced Genetic Elements Expand
Characteristics of Gossypium hirsutum (Cotton) Expand
Donor Organism Characteristics Expand
Modification Method Expand
Characteristics of the Modification Expand
Environmental Safety Considerations Expand
Food and/or Feed Safety Considerations Expand
Cotton (Gossypium hirsutum L.) is primarily grown for its seed bolls that produce fibres used in numerous textile products. The major producers of cotton seed and lint are China, the United States, India, Pakistan, Brazil, Uzbekistan and Turkey.
About two thirds of the harvested cotton crop is seed, which is separated from the lint during ginning. The cotton seed is crushed to produce cottonseed oil, cottonseed cake (meal) and hulls. Cottonseed oil is used primarily as cooking oil, in shortening and salad dressing, and is used extensively in the preparation of snack foods such as crackers, cookies and chips. The meal and hulls are an important protein concentrate for livestock, and may also serve as bedding and fuel. Linters, or fuzz, which are not removed in ginning, are used in felts, upholstery, mattresses, twine, wicks, carpets, surgical cottons, and in industrial products such as rayon, film, shatterproof glass, plastics, sausage skins, lacquers, and cellulose explosives.
Effective weed management is critical to cotton production. The removal of weeds early in the growing season extremely important in cotton production. Young cotton seedlings grow slowly early in the season and are not very competitive. Early weed pressure has detrimental effects on final yield. Weeds can also be detrimental later in the growing season; weeds can interfere with harvesting, and can result in a reduction in lint quality due to trash or staining. Precautions such as pre-plant tillage or herbicide application are common approaches for reducing weed competition, as are multiple herbicide treatments. The broadleaf weeds are the most difficult to control because there are few herbicide options available and many producers will use as many as four herbicides per year in an effort to control weeds.
Cotton lines 1445 and 1698 were genetically engineered to express resistance to glyphosate, the active ingredient in the herbicide Roundup®, allowing for its use as a weed control option. In order to obtain field tolerance to glyphosate herbicide, a bacterial gene encoding a glyphosate-tolerant form of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was introduced into the cotton genome by Agrobacterium-mediated transformation.
The EPSPS enzyme is present in all plants, bacteria, and fungi, and is part of an important biochemical pathway called the shikimate pathway, which is involved in the production of aromatic amino acids and other aromatic compounds. When conventional cotton plants are treated with glyphosate, the plants cannot produce the aromatic amino acids needed to grow and survive. EPSPS is not present in mammals, birds or aquatic life forms, which do not synthesize their own aromatic amino acids. For this reason, glyphosate has little toxicity to these organisms. The EPSPS enzyme is naturally present in foods derived from plant and microbial sources.
Cotton lines 1445 and 1698 were field tested in the United States from 1991 to 1994. Compared with non-transgenic control lines, susceptibilities to diseases such as bacterial blight, boll rot, Verticillium wilt, and Ascochyta blight were unchanged. Similarly, no differences were noted in the susceptibility of the transformed cotton lines to insect pests, such as aphids, fleahoppers, boll weevils, tobacco budworm, cotton bollworm, and thrips, when compared to non-transformed cotton lines. Reports demonstrated that the cotton lines 1445 and 1698 did not exhibit weedy characteristics, and had no effect on non-target organisms or the general environment. The transformed lines were not expected to impact on threatened or endangered species.
Cotton plants are primarily self-pollinating, but insects, especially bumblebees and honeybees, also distribute cotton pollen. Cotton can cross-pollinate with compatible species including G. hirsutum (wild or under cultivation), G. barbadense (cultivated Pima cotton), and G. tomentosum. Overall, the probability of gene transfer to wild species in unmanaged ecosystems is low due to the relatively isolated distribution of Gossypium species, different breeding systems, and genome incompatibility. Assuming proximity, synchronicity of flowering and availability of insects, transgenic cotton lines 1445 and 1698 may freely hybridize with other G. hirsutum varieties.
Human consumption of cotton products is limited to refined cottonseed oil and cellulose from processed linters of cottonseed. Processed linters are essentially pure cellulose, and are subjected to heat and solvent treatment that would be expected to remove and destroy DNA. It is generally accepted that the refined oil does not contain protein as the refining process includes heat, solvent and alkali treatments that would remove and destroy any DNA and protein present. It was concluded that there was little potential for human dietary exposure to the novel proteins expressed in these transgenic cotton lines.
A compositional comparison of cottonseed oil from each line was made to commercial non-transgenic cottonseed oil. Parameters measured included proximate analysis (protein, fat, ash, carbohydrates, crude fibre, and moisture), amino acid and fatty acid composition, and levels of tocopherols. Protein concentrations in the transgenic lines were slightly higher than in the control lines, but still fell within the normal range for cotton. Small differences were also seen in the fatty acid composition of the seed oil, and in total lipid content, however these differences were minor and values remained within the expected range. It was also determined that the transgenic lines contained levels of gossypol and cyclopropenoid fatty acids, toxic substances naturally found in cotton, within the normal range of variation reported for conventional cotton cultivars. Based on these data it was determined that the refined oil and processed linters derived from transgenic cotton lines 1445 and 1698 were nutritionally and compositionally comparable to that from conventional cotton and not likely to impact the nutritional quality of the food supply.
The assessment of the potential allergenicity of the CP4 EPSPS protein was based on an examination of its physiochemical properties, as compared with the characteristics of known protein allergens, amino acid sequence homology with known allergens, and its abundance in food. Data were presented to show that, unlike allergenic proteins, CP4 EPSPS was rapidly degraded in simulated gastric fluids and was inactivated by heat treatment. An amino acid sequence comparison did not reveal any homologies between known protein allergens or toxins and the CP4-EPSPS protein. In addition, refined cottonseed oil and cellulose from linters are devoid of protein and, given that most allergens are proteins, the consumption of these products is unlikely to result in an allergic reaction. These data supported the conclusion that the CP4-EPSPS protein, and thus 1445 and 1698 cotton, possessed little or no potential for allergenicity.
Links to Further Information Expand
This record was last modified on Monday, August 22, 2016