GM Crop Database

Database Product Description
 
DAS-157-1 (TC1507)
Host Organism
Zea mays L. L. (Maize) Herculex I
 
Trait
Resistance to European corn borer (Ostrinia nubilalis); phosphinothricin (PPT) herbicide tolerance, specifically glufosinate ammonium.
 
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.
 
Company Information
Mycogen (c/o Dow AgroSciences); Pioneer (c/o Dupont)



  
 
 
Summary of Regulatory Approvals
 
Country Environment Food and/or Feed Food Feed Marketing
Argentina 2005 2005  
Australia 2003  
Brazil 2008 2008  
Canada 2002 2002 2002  
China 2004  
Colombia 2006  
El Salvador 2009  
European Union 2006 2005  
Japan 2002 2002 2002  
Korea 2002 2004  
Mexico 2003  
Philippines 2003 2003  
South Africa 2002  
Taiwan 2003  
United States 2001 2001  
Uruguay 2011 2011  
Click on the country name for country-specific contact and regulatory information.
Notes
China Approval renewed on 20 December 2006, valid until 20 December 2009.

Introduction
 
Maize line TC1507 was genetically modified to contain two novel genes, cry1Fa2 and pat, for insect resistance and herbicide tolerance respectively. Both genes were introduced into the parental maize hybrid line Hi-II by particle acceleration (biolistic) transformation.

The cry1Fa2 gene, isolated from the common soil bacterium Bacillus thuringiensis (Bt) var. aizawai, produces the insect control protein Cry1F, a delta-endotoxin. Cry proteins, of which Cry1F is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1F is lethal only when eaten by the larvae of lepidopteran insects (moths and butterflies), 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 the delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.

The Cry1F protein expressed in TC1507 provides protection against European corn borer (ECB), southwestern corn borer (SWCB), fall armyworm (FAW), black cutworm (BCW), and some control of corn earworm (CEW).

In addition to the cry1Fa2 gene, TC1507 was developed to allow for the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides (Basta? Rely? Liberty? and Finale?, as a weed control option, and as a breeding tool for selecting plants that have the insect-tolerant cry1F gene. Glufosinate chemically resembles the amino acid glutamate and acts to inhibit an enzyme, called glutamine synthetase, which is involved in the synthesis of glutamine. Essentially, glufosinate acts enough like glutamate, the molecule used by glutamine synthetase to make glutamine, that it blocks the enzyme's usual activity. Glutamine synthetase is also involved in ammonia detoxification. The action of glufosinate results in reduced glutamine levels and a corresponding increase in concentrations of ammonia in plant tissues, leading to cell membrane disruption and cessation of photosynthesis resulting in plant withering and death.

Glufosinate tolerance in TC1507 maize is the result of introducing a gene encoding the enzyme phosphinothricin-N-acetyltransferase (PAT) isolated from the common aerobic soil actinomycete, Streptomyces viridochromogenes, the same organism from which glufosinate was originally isolated. The PAT enzyme catalyzes the acetylation of phosphinothricin, detoxifying it into an inactive compound.

Summary of Introduced Genetic Elements
 
Code Name Type Promoter, other Terminator Copies Form
pat phosphinothricin N-acetyltransferase  (S. viridochromogenes) HT CaMV 35S CaMV 35S 3' polyadenylation signal 1 functional;  
cry1Fa2 cry1F delta-endotoxin  (Bacillus thuringiensis var. aizawai) IR ubiquitin (ubi) ZM (Zea mays) promoter and the first exon and intron 3' polyadenylation signal from ORF25 (Agrobacterium tumefaciens) 1 functional; 1-2 partial; Altered coding sequence for optimal expression in plant cells.

Characteristics of Zea mays L. (Maize)
 
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
 
Latin Name Gene Pathogenicity
Bacillus thuringiensis var. aizawai cry1F While target insects are susceptible to oral doses of Bt proteins, no evidence of toxic effects in laboratory mammals or birds.
Streptomyces viridochromogenes pat S. viridochromogenes is ubiquitous in the soil. The spore chains are Spirales and the spore surface is spiny. The spore mass is blue, the reverse is green and its pigments are pH sensistive. It exhibits very slight antimicrobial activity, is inhibited by streptomycin, and there have been no reports of adverse affects on humans, animals, or plants.

Modification Method
 
Transgenic TC1507 maize was produced by biolistic (microprojectile bombardment) transformation of the hybrid maize line Hi-II (Hi-II is a cross between A188 and B73 inbred lines of maize) with plasmid DNA containing sequences corresponding to a modified (synthetic, less than full-length) form of the cry1Fa2 gene from Bacillus thuringiensis var. aizawai strain PS811 and the phosphinothricin N-acetyltransferase (PAT) encoding gene from Streptomyces viridochromogenes.

In order to optimize expression of the Cry1F protein, the nucleotide sequence of the cry1Fa2 gene was modified via in vitro mutagenesis to contain plant-preferred codons. Transcription of the cr1Fa2 gene was directed by the promoter and a 5' untranslated region from the maize ubiquitin (ubi) gene including the first exon and intron. The 3' termination/polyadenylation sequences were derived from the Agrobacterium tumefaciens open reading frame 25 (ORF25 PolyA). The ubi exon and intron included in this construct (PHI8999) have no effect on the structure of the Cry1F product, only on the expression of the gene.

Transcriptional regulation of the pat gene was via promter and terminator sequences derived from the 35S transcript of cauliflower mosaic virus (CaMV).

Characteristics of the Modification
 
The Introduced DNA
Southern blot analysis of genomic DNA isolated from seed of different generations of progeny plants demonstrated that the parental transgenic line, TC1507, contained a single copy of an intact fragment containing both the cry1Fa2 and pat gene constructs with their associated noncoding regulatory regions and a second copy of the cry1Fa2 coding region lacking the majority of the associated ubiquitin regulatory sequences; and (2) these genetic constructs were stably inherited and cosegregated over four generations of backcrossing.

Genetic Stability of the Introduced Trait
The expression of Cry1F protein in hybrid progeny derived from TC1507 was measured using enzyme linked immunosorbent assay (ELISA). Using a chi square analysis with a 95% confidence interval, a Mendelian ratio of 1:1 was observed for first generation progeny. This pattern of segregation was consistent with the integration of a single functional copy of the cry1Fa2 gene in the original transformation event.

Expressed Material
Levels of expression of Cry1F protein from TC1507 pollen, grain, and grain-derived feeds were measured using quantitative ELISA or Western immunoblotting, and biological activity was determined using insect bioassays with either tobacco budworm or European corn borer larvae.

Cry1F protein was detectable in whole plants (minus the roots) collected at four weeks prior to pollination and following senescence and in leaves, pollen, silk, stalk, and mature grain; whereas PAT was only detectable in leaf tissue. Levels of Cry1F protein expressed in TC1507 ranged from an average of 32 ng/mg in pollen to an average of 110.9 ng/mg total protein in leaf tissue and 89.8 ng/mg total protein in grain samples. Western immunoblotting of sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE) separated proteins in trypsinized plant extracts prepared from TC1507 leaf tissue revealed the presence of a 65 kDa moiety corresponding to the trypsin-resistant core of the Cry1F delta-endotoxin.

The amounts of detectable PAT protein in TC1507 leaf tissue ranged up to 40.8 ng/mg total protein but were undetectable in other tissues, such as pollen, silk, stalk, and grain.

Based on a bioassay with the tobacco budworm (Heliothis virescens), a target species, purified Cry1F proteins incorporated into test soils biodegraded with a half-life of approximately 3.13 days. This half-life is very comparable with the 4-7 days in published reports for other Cry proteins.

Environmental Safety Considerations
 
Outcrossing
Since pollen production and viability were unchanged by the genetic modification resulting in TC1507, pollen dispersal by wind and outcropping frequency should be no different than for other maize varieties. Gene exchange between TC1507 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. Feral species related to corn, as found within Canada or the United States, cannot be pollinated due to differences in chromosome number, phenology (periodicity or timing of events within an organism?s life cycle as related to climate, e.g., flowering time) and habitat.

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. Three species of Tripsacum have been reported in the continental United States: T. dactyloides, T. floridanum and T. lanceolatum. Of these, T. dactyloides, Eastern Gama Grass, is the only species of widespread occurrence and of any agricultural importance. It is commonly grown as a forage grass and has been the subject of some agronomic improvement (i.e., selection and classical breeding). T. floridanum is known from southern Florida and T. lanceolatum is present in the Mule Mountains of Arizona and possibly southern New Mexico. Even though some Tripsacum species occur in areas where maize is cultivated, gene introgression from maize under natural conditions is highly unlikely, if not impossible. Hybrids of Tripsacum species with Zea mays are difficult to obtain outside of the controlled conditions of laboratory and greenhouse. Seed obtained from such crosses are often sterile or progeny have greatly reduced fertility.

Weediness Potential
No competitive advantage was conferred to TC1507 that would 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 Bt proteins are not toxic to humans, other vertebrates, and beneficial insects.

Maize inbreds and hybrids expressing the Cry1F protein were compared to their non-transformed counterpart for relative abundance of beneficial arthropods, including: lady beetles (Cycloneda munda & Coleomegilla maculata), predacious Carabids, brown lacewings (Hemerobiidae), green lacewings (Chrysoperla plorabunda), minute pirate bugs (Orius insidiosus), assassin bugs (Reduviidae), damsel bugs (Nabidae), Ichneumonid and Braconids (parasitic wasps), damselflies and dragonflies, and spiders. Visual counts showed no significant differences between the number of arthropods collected in TC1507 maize and the non-transgenic isolines with two exceptions. There was a significantly greater number of lady beetles in the 1507 line (1.2 per test plant vs. 0.6 per control plant), and significantly more Orius were found in the 1507 line then the non-transgenic line on two of the three sample dates. In summary, these field studies demonstrated that Cry1F 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 honeybee 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.

An additional study was conducted on the effect of Cry1F on neonate monarch butterfly larvae when fed a 10,000 ng/mL diet dose. First instar larval weight and mortality were recorded after seven days of feeding. Although there was some growth inhibition, there was no mortality to monarchs fed the 10,000 ng/mL diet, the highest rate tested. Since pollen doses equivalent to 10,000 ng/mL diet are not likely to occur on milkweed leaves in nature, it can be concluded that Cry1F protein will not pose a risk to monarchs.

Impact on Biodiversity
TC1507 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 risk of transferring genetic traits from TC1507 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 TC1507 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
 
Nutritional Data
Forage and grain from TC1507 maize were analyzed for nutritional composition and compared to the nutritional composition of non-transgenic versions of the same maize hybrids. With respect to forage, there were no significant differences in the respective levels of protein, fat, neutral detergent fibre (NDF), or ash between the transgenic or non-transgenic control lines. The level of acid detergent fibre (ADF) in TC1507 was lower than the control line, but remained within the range of values reported in the scientific literature. Analyses of calcium and phosphorus in forage from TC1507 and the control non-transgenic line were determined to be 0.22 and 0.23 per cent, and 0.25 and 0.24 per cent, respectively.

Grain from TC1507 was found to have similar levels of protein, ADF, NDF and ash as grain from non-transgenic maize hybrids, however, the level of fat was significantly lower. This lower fat content was not considered biologically significant as it was still within the range of values reported for other commercial maize varieties. In examining the fatty acid profile, it was determined that the transgenic line had lower levels of stearic and oleic acid but higher levels of linoleic and linolenic acids than the non-transgenic control. Although differences were noted, they remained within the normal range of variation reported for maize grain. The levels of calcium, phosphorus, copper, iron, magnesium, manganese, and zinc in TC1507 grain were similar to levels measured in grain from the non-transgenic control line. The levels of essential amino acids in TC1507 grain were within the norms reported in the literature. With respect to vitamins, TC1507 had lower levels of vitamin B1 but higher levels of total tocopherols than the non-transgenic control. Although different, these values were within published ranges.

There were no differences in the levels of phytic acid between the transgenic and non-transgenic lines, and the level of trypsin inhibitor in both TC1507 and the non-transgenic control was below the threshold of detection (2000 TIU/g).

Links to Further Information
 
Canadian Food Inspection Agency, Plant Biosafety Office[PDF Size: 43059 bytes]
Decision Document DD2002-41: Determination of the Safety of Dow AgroSciences Canada Inc. and Pioneer Hi-Bred International's Insect Resistant and Glufosinate - Ammonium Tolerant Corn (Zea mays L.) Line 1507.
Comiss? T?nica Nacional de Biosseguran? - CTNBio (Brazil)[PDF Size: 625824 bytes]
Risk Assessment of Insect Resistant Maize (TC 1507)
European Commission[PDF Size: 51940 bytes]
COMMISSION DECISION of 3 March 2006 authorising the placing on the market of food containing, consisting of, or produced from genetically modified maize line 1507 (DAS-?5?-1) pursuant to Regulation (EC) No 1829/2003 of the European Parliament and of the Council.
European Commission: Community Register of GM Food and Feed[PDF Size: 12040 bytes]
Notification of the placing on the Community Register of DAS-?5?-1 (TC1507).
European Food Safety Authority[PDF Size: 135846 bytes]
Opinion of the Scientific Panel on Genetically Modified Organisms on an application (reference EFSA-GMO-NL-2004-02) for the placing on the market of insect-tolerant genetically modified maize 1507, for food use, under Regulation (EC) No 1829/2003 from Pioneer Hi-Bred International/Mycogen Seeds
Food Standards Australia New Zealand[PDF Size: 455928 bytes]
Draft assessment report, application A446: food derived from insect-protected and glufosinate ammonium-tolerant corn line 1507.
Food Standards Australia New Zealand[PDF Size: 436192 bytes]
Final Assessment Report: Application A446 - Insect / glufosinate resistant corn line 1507
Impact of Bt corn pollen on monarch butterfly populations: A risk assessment[PDF Size: 166577 bytes]
Mark K. Sears, Richard L. Hellmich, Diane E. Stanley-Horn, Karen S. Oberhauser, John M. Pleasants, Heather R. Mattila, Blair D. Siegfried, and Galen P. Dively (2001). Proc. Natl. Acad. Sci. USA Early Edition
Japanese Biosafety Clearing House, Ministry of Environment[PDF Size: 178037 bytes]
Outline of the biological diversity risk assessment report: Type 1 use approval for DAS-?5?-1
Office of Food Biotechnology, Health Canada[PDF Size: 144926 bytes]
NOVEL FOOD INFORMATION? FOOD BIOTECHNOLOGY Cry1F INSECT-RESISTANT/GLUFOSINATE-TOLERANT MAIZE LINE 1507
Philippines Department of Agriculture, Bureau of Plant Industry[PDF Size: 25260 bytes]
Determination of the Safety of Pioneer Hi-Bred?s And Dow Agro Sciences? Corn 1507 (Insect resistant, herbicide tolerant Corn) for Direct Use as Food, Feed and For Processing
Swiss Federal Office of Public Health[PDF Size: 100246 bytes]
Information to the Swiss authorities on the potential environmental impact of genetically modified plants in accordance with Annexes IIB and III of Directive 90/220/EEC (August 14, 2001)
U.S. Department of Agriculture, Animal and Plant Health Inspection Service[PDF Size: 3238819 bytes]
Petition for Determination of Nonregulated Status for Cry1F Insect-Resistant and Glufosinate-Tolerant Maize Line 1507 (CBI-deleted)
US Environmental Protection Agency[PDF Size: 669353 bytes]
Biopesticide Registration Action Document: Bacillus thuringiensis Cry1F Corn.
US Food and Drug Administration[PDF Size: 89238 bytes]
Memorandum to file concerning insect resistant and herbicide tolerant maize line 1507
USDA-APHIS Environmental Assessment[PDF Size: 449681 bytes]
USDA/APHIS Decision on Mycogen Seeds c/o Dow AgroSciences LLC and Pioneer Hi-Bred International, Inc. Petition 00-136-01P Seeking a Determination of Nonregulated Status for Bt Cry1F Insect Resistant, Glufosinate Tolerant Corn Line 1507

References
 
Efficacy
Buntin,G.D. (2008). Corn expressing Cry1Ab or Cry1F endotoxin for fall armyworm and corn earworm (Lepidoptera: noctuidae) management in field corn for grain production. Florida Entomologist 91(4): 523-530.
Eichenseer, H., Strohbehn, R. and Burks, J. (2008). Frequency and severity of western bean cutworm (Lepidoptera: Noctuidae) ear damage in transgenic corn hybrids expressing different Bacillus thuringiensis cry toxins. J Econ Entomol. 101(2):555-563.
Siebert, W.A., Babock, J.M., Nolting, S., Santos, A.C., Adamczyk, J.J., Neese, P.A., King, J.E., Jenkins, J.N., McCarty, J., Lorenz, G.M., Fromme, D.D. and Lassiter, R.B. (2008). Efficacy of Cry1F insecticidal protein in maize and cotton for control of fall armyworm (Lepidoptera: Noctuidae).Florida Entomologist 91(4): 555-565.
Environmental Fate
Shan, G., Embrey, S.K., Herman, R.A. and McCormick, R. (2008). Cry1F protein not detected in soil after three years of transgenic Bt corn (1507 corn) use. Environ Entomol. 37(1): 255-62.
Feeding Studies
MacKenzie, SA; Lamb, I; Schmidt, J; Deege, L; Morrisey, MJ; Harper, M; Layton, RJ; Prochaska, LM; Sanders, C; Locke, M; Mattsson, JL; Fuentes, A; and Delaney, B. (2007). Thirteen week feeding study with transgenic maize grain containing event DAS-?5?-1 in Sprague-Dawley rats. Food Chem. Toxicol. 45(4): 551-562.
Insect Resistance
Pereira, E.J.G., Lang, B.A., Storer, N.P. and Siegfried, B.D. (2008). Selection for Cry1F resistance in the European corn borer and cross-resistance to other Cry toxins. Entomologia Experimentalis et Applicata 126(2): 115-121.
Non-Target Organism Studies
Higgins, L., Babcock, J., Neese, P., Layton, R., Moellenbeck, D., Storer, N. (2009). Three-year field monitoring of cry1F, event DAS-01507-1, maize hybrids for nontarget arthropod effects. Environmental Entomology 38(1): 281-292.
Wolt, J.D., Conlan, C.A. and Majima, K. (2005). An ecological risk assessment of Cry1F maize pollen impact to pale grass blue butterfly. Environ. Biosafety Res. 4: 243-251.
Nutritional Equivalence
Faust, M; Smith, B; Rice, D; Owens, F; Hinds, M; Dana, G; and Hunst, P. (2007). Performance of lactating dairy cows fed silage and grain from a maize hybrid with the cry1F trait versus its nonbiotech counterpart. J. Dairy Sci. 90: 5706?5713.
Scheideler, S.E., Rice, D., Smith, B., Dana, G. and Sauber, T. (2008). Evaluation of nutritional equivalency of corn grain from DAS-?5?-1 (Herculex* I) in the diets of laying hens. J. Appl. Poult. Res. 17: 383?389.
Sindt, J., Drouillard, J., Loe, E., Kessen, T., Sulpizio, M., Montgomery, S., Rice, D., Hinds, M., Smith, B., Owens, F., Dana, G. and Hunst, P. (2007). Effect of corn containing the Cry1F protein on performance of beef heifers fed a finishing diet based on steam-flaked corn. The Professional Animal Scientist 23: 632?636.


THIS RECORD WAS LAST MODIFIED ON SUNDAY, MARCH 01, 2009
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