Database Product Description
- Host Organism
- Triticum aestivum L. (Wheat)
- Glyphosate herbicide tolerance.
- Trait Introduction
- Agrobacterium tumefaciens-mediated plant transformation.
- Proposed Use
- Production of T. aestivum for human food and livestock feed. This material will not be grown outside the normal production area for wheat.
- Product Developer
- Monsanto Company
Summary of Regulatory Approvals
Summary of Introduced Genetic Elements Expand
Characteristics of Triticum aestivum L. (Wheat) Expand
Donor Organism Characteristics Expand
Modification Method Expand
Characteristics of the Modification Expand
Food and/or Feed Safety Considerations Expand
Commercial wheat is comprised mainly of two species: common, or bread wheat (T. aestivum L.) and durum wheat (T. durum Desf.). Bread wheat is classified into several types, based on vernalisation requirement (winter and spring types) and kernel hardness. The hard types of bread wheat are high in protein, especially gliadins and glutenins. The high levels of these protein fractions in the flour impart elasticity to bread dough and allow it to expand during leavening and baking. Soft wheats are low in protein, and have low levels of gliadin and glutenin. These wheats are milled into flour for use in bakery products such as cakes, pastries, and unleavened breads. Durum wheat produces very hard, almost vitreous kernels due to its high protein content. This wheat is milled into semolina for the production of pasta and couscous.
Harvested wheat consists of a naked kernel, unlike other cereals such as rice, barley or oats that retain their hull (i.e., the palea and lemma) after harvest. The wheat kernel is loosely enclosed within the palea and lemma of each spikelet; these are eliminated as chaff during threshing. The wheat kernel is milled into white flour by removing the bran, aleurone layers and the germ prior to grinding; whole-wheat flour retains these fractions. By-products of wheat milling include: bran, germ, shorts and middlings. Some of these by-products are used as human food (i.e., bran, germ), and others, as livestock feed. Grain that does not meet the grade for food use can be used as animal feed, mainly for poultry and swine, but also for cattle. Wheat can also be fed as forage, either as pasture prior to stem elongation, or as ensilage. Wheat is also used in the brewing and distilling industries.
Weeds are a major production problem in wheat cultivation. Weeds compete for light, water and nutrients, and can also cause lodging and problems with harvesting. The seeds of several weed species are almost impossible to clean out of harvested wheat (e.g., Avena fatua L. wild oats), causing loss of quality and downgrading of the crop. Weeds can be managed using a combination of cultural practices (e.g., seed bed preparation, use of clean [certified] seed, narrow row spacing, fertilizer banding), integrated weed management (e.g., weed scouting, economic thresholds) and the use of herbicides. Depending on the weed species present, herbicides can be applied before the crop emerges (e.g., amitrole, glyphosate, trifluralin), or after (e.g., 2-4D, bromoxynil, dicamba, fenoxaprop-p-ethyl, MCPA, metsulfuron methyl). The build-up of weed populations can be stemmed by applying herbicides on summer-fallowed fields, and by practicing crop rotation, which allows the use of different herbicides. Rotating among herbicide groups also prevents the development of herbicide-resistant biotypes.
Roundup Ready® wheat (MON 71800) was developed to allow the use of glyphosate, the active ingredient in the herbicide Roundup®, as a weed control option in spring wheat production. This genetically engineered spring wheat contains a novel form of the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) that allows MON 71800 to survive an otherwise lethal application of glyphosate. The EPSPS gene introduced into MON 71800 was isolated from a strain of the common soil bacterium Agrobacterium tumefaciens strain CP4, and the novel form of the EPSPS enzyme produced by this gene is tolerant to glyphosate.
The EPSPS enzyme is part of the shikimate pathway, an important biochemical pathway in plants involved in the production of aromatic amino acids and other aromatic compounds. When conventional plants are treated with glyphosate, the plants cannot produce the aromatic amino acids needed for growth and survival. EPSPS is present in all plants, bacteria, and fungi. It is not present in animals, since these organisms are unable to synthesize their own aromatic amino acids. Because the aromatic amino acid pathway is not present in mammals, birds, or aquatic life forms, glyphosate has little, if any, toxicity for these organisms. The EPSPS enzyme is naturally present in foods derived from plant and microbial sources. MON 71800 was developed by introducing two CP4 EPSPS genes into the spring wheat variety ‘Bobwhite’ using Agrobacterium-mediated transformation.
The food and livestock safety of MON 71800 wheat was based on the safety assessment of the CP4 EPSPS protein and the level of expression of the protein in the grain. The CP4 EPSPS proteins constitutes a small amount of the total protein in MON 71800 so there is little dietary exposure. The lack of toxicity or allergenicity of CP4 EPSPS was demonstrated from the results of laboratory and safety studies. The nutritional equivalence and wholesomeness of MON 71800 wheat compared to conventional wheat was demonstrated by the analysis of key nutrients in the grain including proximates (e.g., crude protein, crude fat, crude fibre, ash, moisture), total dietary fibre, sugars, starch, amino acid and fatty acid composition, B vitamins and vitamin E, minerals, as well the composition in the anti-nutrient phytic acid.
Links to Further Information Expand
This record was last modified on Friday, March 26, 2010