GM Crop Database

Database Product Description

MON-ØØ81Ø-6 (MON810)
Host Organism
Zea mays L. (Maize) Yieldgard®
Trait
Resistance to European corn borer (Ostrinia nubilalis).
Trait Introduction
Microparticle bombardment of plant cells or tissue
Proposed Use

Production of Z. mays for human consumption (wet mill or dry mill or seed oil), and meal and silage for livestock feed. These materials will not be grown outside the normal production area for corn.

Product Developer
Monsanto Company

Summary of Regulatory Approvals

Country Food Feed Environment Notes
Argentina 1998 1998 1998
Australia 2000
Brazil 2007 2007 2007
Canada 1997 1997 1997
China 2004 2004
Colombia 2003
European Union 1998 1998 1998 View
Japan 1997 1997 1996
Korea 2002 2004
Mexico 2002 2002
Netherlands View
Philippines 2002 2002 2002
South Africa 1997 1997 1997
Switzerland 2000 2000
Taiwan 2002
United Kingdom View
United States 1996 1996 1995
Uruguay 2003 2003 2003

Introduction Expand

Maize line MON 810 (trade name YieldGard) 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 produces a truncated version of the insecticidal protein, Cry1Ab, derived from Bacillus thuringiensis. Delta-endotoxins, such as the Cry1Ab protein expressed in MON 810, 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 enhanced CaMV 35S, maize HSP70 intron None. Lost through 3' truncation during integration 1 Truncated

Characteristics of Zea mays L. (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 cry1Ab-Ac

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.

Modification Method Expand

Maize line MON 810 was produced by biolistic transformation of maize genotype Hi-II with a mixture of plasmid DNAs, PV-ZMBK07 and PV-ZMGT10. The PV-ZMBK07 plasmid contained the cry1Ab gene and PV-ZMGT10 plasmid contained the CP4 EPSPS and gox genes. Both plasmids contained the nptII gene under the control of a bacterial promoter required for selection of bacteria containing either plasmid, and an origin of replication from a pUC plasmid (ori-pUC) required for replication of the plasmids in bacteria.

Characteristics of the Modification Expand

The Introduced DNA

Southern blot analysis of MON810 genomic DNA indicated the incorporation of a single copy of the truncated cry1Ab gene, together with the enhanced CaMV 35S (E35S) promoter and hsp70 leader sequences. The NOS 3' termination signal, present in plasmid PV-ZMBK07, was not integrated into the host genome but was lost through a 3' truncation of the gene cassette. The native Cry1Ab protein (HD-1) has a molecular weight of 131 kD while the inserted, plant expressed cry1Ab gene codes for a truncated protein with a molecular weight of 91 kD, as confirmed by Western blot analysis of MON810 tissue extracts. Evidence was provided that no plasmid backbone sequences from the plasmid PV-ZMGT10 were integrated into the MON810 genome. Further Southern blot analysis indicated that the genes for glyphosate tolerance (CP4 EPSPS) and antibiotic resistance (neo) were not transferred to line MON 810 and the absence of the CP4 EPSPS and gox gene products was also confirmed by Western blotting. The CP4 EPSPS and GOX protein encoding genes were presumed to have been inserted into the initial transformant at a separate genetic loci from the cry1Ab gene and then subsequently lost through segregation during the crossing events leading to line MON810.

Genetic Stability of the Introduced Trait

Segregation and stability data were consistent with a single site of insertion of the cry1Ab gene into the MON810 genome. The stability of the insertion was demonstrated through multiple generations of crossing. MON810 was derived from the third generation of backcrossing and stable integration of the single insert was demonstrated through all three generations by Southern Blot analysis.

Expressed Material

The synthetic cry1Ab gene was linked to a strong constitutive promoter and modified for maximum expression in corn. The amino acid sequence of the toxin expressed in the modified corn was found to be identical to that occurring naturally, and equivalent to that produced for use as the biopesticide that is widely used by the organic food industry. Average protein expression, as measured in samples obtained from field trials at six locations, was 9.35 µg/g (fresh weight) in leaves and 0.31 µg/g (f.w.) in seeds. The concentration of expressed toxin, as determined from a single sample obtained from one site, was 4.15 µg/g (f.w.) in the whole plant and 0.09 µg/g (f.w.) in pollen. Protein expression ranged from 7.93 to 10.34 µg/g (f.w.) in leaves, from 0.19 to 0.39 µg/g (f.w.) in grain, and from 3.65 to 4.65 µg/g (f.w.) in the whole plant. Protein expression declined over the growing season as indicated by the Cry1Ab protein concentrations in leaves assayed over the growing season. The Cry1Ab protein was shown to degrade readily in the environment. The plant expressed protein had DT50 and DT90 values (time to degrade to 50% and 90 % of the original bioactivity) of 2 and 15 days respectively.

Environmental Safety Considerations Expand

Outcrossing

Since pollen production and viability were unchanged by the genetic modification resulting in MON810, pollen dispersal by wind and outcropping frequency should be no different than for other maize varieties. Gene exchange between MON810 maize 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 no plant species closely-related to maize in the wild, the risk of gene flow to other species appears remote. Maize (Zea mays ssp. mays) freely hybridizes with annual teosinte (Zea mays ssp. mexicana) when in close proximity. These wild maize relatives are native to Central America and are not present in Canada and the United States, except for special plantings. Tripsacum, another genus related to Zea, contains sixteen species, of which twelve are native to Mexico and Guatemala. Tripsacum floridanum (Florida gamagrass) is native to the southern tip of Florida. Outcrossing with Tripsacum species is not known to occur in the wild and it is only with extreme difficulty that maize can be crossed with Tripsacum.

Weediness Potential

No competitive advantage was conferred to MON810, 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. 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 insecticidally active core of the Bt protein expressed in MON810 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. Specific feeding trials were also carried out with a number of non-target species, including honey bee larvae and adults, green lacewing, parasitic hymenopterans, ladybird beetles, daphnia (aquatic invertebrates), earthworm, and collembola (soil dwelling invertebrates). In all cases there were no observable adverse effects. 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.

Impact on Biodiversity

MON810 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 North America is remote, it was determined that risk of transferring genetic traits from MON810 maize to species in unmanaged environments was insignificant.

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 MON810 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.

Food and/or Feed Safety Considerations Expand

Dietary Exposure

Little whole kernel or processed maize is directly consumed by humans in comparison to maize-based food ingredients. Maize is a raw material for the manufacture of starch, the majority of which is converted to a variety of sweetener and fermentation products, including high fructose syrup and ethanol. Maize oil is commercially processed from the germ. These materials are components of many foods including bakery and dairy goods, and the human food uses of grain from MON810 are not expected to be different from the uses of non-transgenic field maize varieties. As such, the dietary exposure to humans of grain from insect resistant hybrids will not be different from that for other commercially available field maize varieties.

Nutritional Data

Data on fatty acid profiles, protein content, amino acid composition, crude fibre, ash, phytate, and moisture content were provided for samples of MON810 grown in field trials in various locations in the United States and Europe. Comparisons of these parameters between MON810 and a non-transgenic control maize line did not reveal any biologically significant differences. The observed variations in nutritional composition were judged to arise from normal variability rather than as a result of the inserted novel traits. As a percentage of dry weight, the component analyses for line MON810, are approximately: protein 13.1%; fat 3.0%; moisture 12.4%; calories 408 Kcal/100g; ash 1.6%; and carbohydrate 82.4%.

Toxicity

The trypsin-resistant Cry1Ab protein core expressed in insect-protected MON810 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 30 years. The low potential for toxicity of plant-expressed Cry1Ab protein was further demonstrated by a lack of amino acid sequence homology with known protein toxins, rapid digestion in simulated gastric juices, and lack of toxicity in feeding studies with laboratory animals. An acute oral toxicity study was done to assess the potential mammalian toxicity of Cry1Ab protein purified from Escherichia coli transformed with the same cry1Ab gene used to produce MON810. Bacterial expressed protein was used in these studies because insufficient amounts could be purified from plant tissue. Data demonstrating the molecular equivalence of bacterial and plant-expressed Cry1Ab protein were provided. The Cry1Ab core protein was administered to groups of ten male and female CD-1 mice in doses up to 4000 mg/kg body weight. These doses were well above the level of expression found in insect-protected maize plants and represented a 200-1000 fold excess over the level of exposure that would be predicted based on consumption of MON810 grain. As a control, equivalent groups of mice were administered either 4000 mg/kg bovine serum albumin or 66.66 mg/kg sodium carbonate solution (vehicle control). Clinical observations were performed and body weights and food consumption were determined. One female mouse belonging to the vehicle control died during the test — on day 1. The death of the control female was considered a result of the intubation procedure. As there were no deaths in other treated mice, or at higher exposure levels, the death was not considered to be treatment related. Mice were observed up to 9 days after dosing and no treatment related effects on body weight, food consumption, survival, or gross pathology upon necropsy were observed for mice administered the Cry1Ab test protein.

Allergenicity

The Cry1Ab protein was evaluated for potential allergenicity by examining: (1) physiochemical characteristics; (2) amino acid sequence homology to known protein allergens; (3) digestibility; and (4) history of safe use of microbial insecticides containing this protein. Although the molecular weight of the Cry1Ab trypsin-resistant core protein, 63 kDa, was within the size range of known protein allergens, unlike many of these allergens it was not glycosylated. A search for amino acid sequence homology between the Cry1Ab protein and the amino acid sequences of 219 known allergens, using a database assembled from the public domain databases GenBank, EMBL, Pir and SwissProt, did not reveal any significant matches. Maize products are an important alternative to wheat flour for individuals afflicted with celiac disease, an immune mediated food intolerance for which wheat gliadins have been implicated as the causal agent. In light of the importance of maize products to these individuals, a sequence similarity search was conducted and no amino acid sequence homologies between the Cry1Ab protein and gliadins were detected. The digestibility of Cry1Ab protein was determined experimentally using in vitro mammalian digestion models. Purified Cry1Ab trypsin-resistant core protein (63 kDa) was added to simulated gastric and intestinal fluids and incubated at 37ºC. The degradation of the protein in the digestion fluid was assessed over time by Western blot analysis and insect bioassay. In simulated gastric fluid, more than 90% of the Cry1Ab protein was degraded after 2 minutes incubation, while in simulated intestinal fluid the trypsin-resistant Cry1Ab core protein was not further degraded after more than 19 hrs incubation. This latter result was expected as serine proteases, such as trypsin, are the predominant proteolytic components of intestinal fluid. The source of the cry1Ab gene has a long history of use on food crops as a biopesticide and no evidence of adverse effects. This fact, combined with the lack of amino acid sequence homology between Cry1Ab protein and known allergens, and the rapid degradation of Cry1Ab protein in acidic gastric fluids, were sufficient to provide a reasonable certainty of lack of allergenic potential.

Links to Further Information Expand

Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies Australia New Zealand Food Authority Canadian Food Inspection Agency, Plant Biotechnology Office Comissão Técnica Nacional de Biossegurança - CTNBio European Commission Scientific Committee on Plants European Commission: Community Register of GM Food and Feed European Food Safety Authority Impact of Bt corn pollen on monarch butterfly populations: A risk assessment Japanese Biosafety Clearing House, Ministry of Environment Monsanto Company Office of Food Biotechnology, Health Canada PNAS Early Edition (June 2000) THE COMMISSION OF THE EUROPEAN COMMUNITIES U.S.Department of Agriculture, Animal and Plant Health Inspection Service US Environmental Protection Agency US Food and Drug Administration

This record was last modified on Monday, September 2, 2013