GM Crop Database

Database Product Description

MON80100
Host Organism
Zea mays (Maize)
Trait
Resistance to European corn borer (Ostrinia nubilalis).
Trait Introduction
Microparticle bombardment of plant cells or tissue
Proposed Use

Production for human consumption and livestock feed.

Product Developer
Monsanto Company

Summary of Regulatory Approvals

Country Food Feed Environment Notes
United States 1996 1996 1995

Introduction Expand

Maize line MON80100 was developed through a specific genetic modification to be resistant to attack by European corn borer (ECB; Ostrinia nubilalis), a major insect pest of maize in agriculture. The novel variety produced the insecticidal protein, Cry1Ab, derived from Bacillus thuringiensis subsp. kurstaki (B.t.k.). Delta-endotoxins, such as the Cry1Ab protein expressed in MON80100, act by selectively binding to specific sites localized on the brush border midgut epithelium of susceptible insect species. Following binding, cation-specific pores are formed that disrupt midgut ion flow and thereby cause paralysis and death. Cry1Ab is insecticidal only to lepidopteran insects, and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.

Summary of Introduced Genetic Elements Expand

Code Name Type Promoter, other Terminator Copies Form
cry1Ab Cry1Ab delta-endotoxin (Btk HD-1) IR CaMV 35S HSP70 intron A. tumefaciens nopaline synthase (nos) 3'-untranslated region Native
CP4 epsps 5-enolpyruvyl shikimate-3-phosphate synthase SM CaMV 35S chloroplast transit peptide from A. thaliana EPSPS gene (CTP1) A. tumefaciens nopaline synthase (nos) 3'-untranslated region
goxv247 glyphosate oxidoreductase HT CaMV 35S chloroplast transit peptide from A. thaliana ribulose-1,5-bisphosphate carboxylase gene (CTP2) A. tumefaciens nopaline synthase (nos) 3'-untranslated region Expression not detected in plants
nptII neomycin phosphotransferase II SM bacterial promoter Not expressed in plant cells.

Characteristics of Zea mays (Maize) Expand

Center of Origin Reproduction Toxins Allergenicity

Mesoamerican region, now Mexico and Central America

Cross-pollination via wind-borne pollen is limited, pollen viability is about 30 minutes. Hybridization reported with teosinte species and rarely with members of the genus Tripsacum.

No endogenous toxins or significant levels of antinutritional factors.

Although some reported cases of maize allergy, protein(s) responsible have not been identified.

Donor Organism Characteristics Expand

Latin Name Gene Pathogenicity
Bacillus thuringiensis subsp. kurstaki EC2.4.2.19

While target insects are susceptible to oral doses of Bt proteins, no evidence of toxic effects in laboratory mammals or birds given up to 10 µg protein/g body weight.

Agrobacterium tumefaciens strain CP4 CP4 epsps

Agrobacterium tumefaciens is a common soil bacterium that is responsible for causing crown gall disease in susceptible plants. There have been no reports of adverse effects on humans or animals.

Modification Method Expand

Maize line MON80100 was produced by biolistic transformation of maize genotype B73 with a mixture of DNA from two plasmids. One plasmid contained a copy of the cry1Ab gene from B. thuriengensis subsp. kurstaki (B.t.k.). Constitutive expression of the cry1Ab gene was controlled by inclusion of sequences from the 35S promoter of cauliflower mosaic virus (CaMV), the HSP70 intron and the 3'-polyadenylation signal of the nopaline synthase (nos) gene from Agrobacterium tumefaciens. The second plasmid contained open reading frames for two selectable marker genes, the CP4 EPSPS enzyme from the common soil bacterium, Agrobacterium tumefaciens sp. CP4, and glyphosate oxidoreductase (goxv247) from Ochrobactrum anthropi sp. strain LBAA. Constitutive expression of these genes in plant cells was under the control of the CaMV 35S promoter and nos terminator. Post-translational targeting of the CP4 EPSPS and glyphosate oxidoreductase enzymes to the chloroplast was accomplished by fusion of the 5'-terminal coding sequences with the chloroplast transit peptide DNA sequences from the Arabidopsis thaliana EPSPS and ribulose-1,5-bisphosphate carboxylase encoding genes, respectively. Both plasmids also contained sequences encoding the enzyme neomycin phosphotransferase II (NPTII) from the Tn5 transposon of Escherichia coli, strain K12. Expression of the neo gene was regulated by a bacterial promoter and was used as a selectable trait to screen transformed E. coli for the presence of the plasmid vector. The expression of CP4 EPSPS and glyphosate oxidoreductase activity were used as selectable markers to identify transformed plants. Apart from the sequences encoding Cry1Ab, CP4 EPSPS and glyphosate oxidoreductase, no other plant-translatable DNA sequences were introduced into the plant genome.

Characteristics of the Modification Expand

Genetic Stability of the Introduced Trait

Maize line MON80100 has been field tested since 1992 in the major maize growing regions of the United States. Southern Blot analysis of genomic DNA from 5 generations of backcrosses of the MON80100 line to the B73 parental line and 4 generations of crosses to an unrelated inbred line confirmed stable inheritance of the cry1Ab gene. Southern blot and segregation analyses indicated that the introduced genes were stably integrated into the maize genome and followed Mendelian rules of inheritance.

Expressed Material

The synthetic cry1Ab gene was linked to a strong constitutive promoter and modified for maximum expression in maize. The endotoxin expressed in the modified maize line MON80100 was found to be identical to that occurring naturally, and equivalent to the active ingredient in microbial formulations of B.t.k. spray. The expression levels of Cry1Ab protein, CP4 EPSPS and glyphosate oxidoreductase were determined in the leaves, kernels and pollen of transgenic maize. In leaves and kernels, the amounts of Cry1Ab and CP4 EPSPS were to be 1.3 or 0.57 µg/g leaf fresh weight and 1.85 or 4.11 µg/g kernel fresh weight, respectively. There were no detectable amounts of Cry1Ab protein in the pollen from transgenic MON80100 maize. Also, glyphosate oxidoreductase and NPTII were not detected in either leaves or kernels from MON80100 maize.

Environmental Safety Considerations Expand

Outcrossing

Since pollen production and viability were unchanged by the genetic modification resulting in MON80100, pollen dispersal by wind and outcrossing frequency should be no different than for other maize varieties. Gene exchange between MON80100 and other cultivated maize varieties will be similar to that which occurs naturally between cultivated maize varieties at the present time. In Canada and the United States, where there are few plant species closely-related to maize in the wild, the risk of gene flow to other species is remote. Cultivated maize, or maize, Zea mays L. subsp. mays, is sexually compatible with other members of the genus Zea, and to a much lesser degree with members of the genus Tripsacum.

Weediness Potential

No competitive advantage was conferred to MON80100, other than that conferred by resistance to European corn borer. Resistance to ECB will not, in itself, render maize weedy or invasive of natural habitats since none of the reproductive or growth characteristics were modified. Cultivated maize is unlikely to establish in non-cropped habitats and there have been no reports of maize surviving as a weed. Maize volunteers are not uncommon but are easily controlled using herbicides or mechanical means. Zea mays is not invasive and is a weak competitor with very limited seed dispersal.

Secondary and Non-Target Adverse Effects

The history of use and literature suggest that the bacterial Bt protein is not toxic to humans, other vertebrates, and beneficial insects. The Bt protein expressed in MON80100 maize (Cry1Ab) was shown to be equivalent to the original microbial protein. This protein is active only against specific lepidopteran insects and no lepidopteran species are listed as threatened or endangered species in Canada or the United States.

Maize inbreds and hybrids expressing the Cry1Ab protein were compared to their non-transformed counterpart for relative abundance of beneficial arthropods. Field studies demonstrated that Cry1Ab had neither a direct nor an indirect effect on the beneficial arthropod populations.

Numerous dietary studies assessed the potential toxicity of the Cry1Ab trypsin-resistant core protein on several nontarget organisms. A protein concentration greater than 10 times the amount that killed target Lepidoptera had no visible effect on honey bees (Apis mellifera L.) or their larvae. Larvae of green lacewing (Chrysopa carnea), a beneficial predatory insect, were not adversely effected when fed moth eggs for seven days that were coated with about eight times the concentration (16.7 ppm) of Cry1Ab core protein that kills ECB. When parasitic hymenoptera, Brachymeria intermedia, which is a beneficial parasite of the housefly (Musca domestica), were exposed to ten times the concentration of activated Cry1Ab protein that kills ECB (20 ppm in honey/water solution) for thirty days there were no treatment-related mortality or signs of toxicity. Similar studes were conducted on Ladybird beetles (Hippodamia convergens), a beneficial predaceous insect which feeds on aphids and other plant insects commonly found on stems and foliage of weeds and cultivated plants. Ladybird beetles exposed to activated Cry1Ab protein at a test concentration of 20 ppm in a honey/water solution for nine days did not exhibit treatment related mortality or signs of toxicity.

A bird study on quails was conducted to assess the wholesomeness of insect protected maize meal fed to quail since birds may feed on maize left in the field after harvest. No mortality occurred in birds fed up to 10% (nominal 100,000 ppm) raw maize seed meal in their diet. Consumption of diet containing 10% of the diet on weight basis of raw maize meal is equivalent to the quail eating 138 seeds/kg body weight per day. The seeds contained 0.57 ppm of the Cry1Ab protein.

In summary, it was determined that when compared with currently commercialized maize varieties, MON810 maize did not present an increased risk to or impact on interacting organisms, including humans, with the exception of specific lepidopteran insect species. It was also concluded that there was no reason to believe that deleterious effects or significant impacts on nontarget organisms, including beneficial organisms, would result from the EPSPS encoding and gox genes used as selectable markers during development of MON80100.

Impact on Biodiversity

MON80100 has no novel phenotypic characteristics that would extend its use beyond the current geographic range of maize production. Since the risk of outcrossing with wild relatives in Canada and the United States is remote, it was determined that the risk of transferring genetic traits from MON80100 maize to species in unmanaged environments was not significant.

Other Considerations

In order to prolong the effectiveness of plant-expressed Bt toxins, and the microbial spray formulations of these same toxins, regulatory authorities in Canada and United States have required developers to implement specific Insect Resistant Management (IRM) Programs. These programs are mandatory for all transgenic Bt-expressing plants, including MON80100 maize, and require that growers plant a certain percentage of their acreage to non-transgenic varieties in order to reduce the potential for selecting Bt-resistant insect populations. Details on the specific design and requirements of individual IRM programs are published by the relevant regulatory authority.

MON80100 maize plants are not likely to eliminate the use of chemical insecticides which are traditionally applied to about 25 to 35% of the total maize acreage planted, since the primary target for most of these applications has been the coleopteran, corn rootworm. MON80100 maize may positively impact current agricultural practices used for insect control by 1) offering an alternative method for control of European corn borer (and potentially other Cry1Ab-susceptible pests of maize); 2) reducing the use of insecticides to control European corn borer and the resulting potential adverse effects of such insecticides on beneficial insects, farm worker safety, and ground water contamination; and 3) offering a new tool for managing insects that have become resistant to other insecticides currently used or expressed in maize, including other Bt-based insecticides.

Food and/or Feed Safety Considerations Expand

Dietary Exposure

The MON80100 line of transgenic maize is not a sweet maize, but rather, a field maize intended mainly for use in animal feed. However, some human food uses are relevant for field maize. The MON80100 maize hybrids would be either dry or wet-milled into various processed maize products. The genetic modification of MON80100 maize will not result in any change in the consumption pattern for this product. Consequently, dietary exposure to this product is anticipated to be the same as for other lines of commercially available field maize.

Nutritional Data

The analysis of nutrients from transgenic MON80100 maize and non-transgenic maize did not reveal any significant differences in the levels of protein, fat, fibre and starch. Similarly, the levels of micronutrients including calcium, phosphorus, potassium and magnesium were within the established ranges for maize. Feeding trials with rats, catfish and quail in which raw or processed maize meal from transgenic MON80100 was incorporated into the diet, did not reveal any significant differences in weight gain, food consumption or gross pathology between test and control subjects. The consumption of products from MON80100 will have no significant impact on the nutritional quality of the food supply.

Toxicity

The trypsin-resistant Cry1Ab protein core expressed in insect-protected MON80100 was identical to the same form of the protein contained in microbial Bt spray formulations that have been safely used in agriculture for more than 40 years. The low potential for toxicity of plant expressed Cry1Ab protein, and CP4 EPSPS and glyphosate oxidoreductase enzymes was demonstrated by a lack of sequence homologies with known mammalian protein toxins.

Allergenicity

The Cry1Ab protein, CP4 EPSPS and glyphosate oxidoreductase enzymes do not possess characteristics typical of known protein allergens. There were no regions of homology when the sequences of three introduced proteins were compared to the amino acid sequences of known protein allergens. Unlike known protein allergens, these proteins were rapidly degraded by acid and/or enzymatic hydrolysis when exposed to simulated gastric or intestinal fluids.

Links to Further Information Expand


This record was last modified on Friday, March 26, 2010