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Genetically modified maize

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Title: Genetically modified maize  
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Subject: StarLink corn recall, MON 863, Genetic engineering, List of varieties of genetically modified maize, 2,4-Dichlorophenoxyacetic acid
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Genetically modified maize

Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both traits are now in use in multiple countries. GM maize has also caused controversy with respect to possible health effects, impact on other insects and impact on other plants via gene flow. One strain, called Starlink, was approved only for animal feed in the US, but was found in food, leading to a series of recalls starting in 2000.


  • Marketed products 1
    • Herbicide resistant maize 1.1
    • Insecticide-producing corn 1.2
    • Drought resistance 1.3
      • Sweet corn 1.3.1
  • Products in development 2
  • Refuges 3
  • Resistance 4
  • Regulation 5
  • Controversy 6
    • Effects on nontarget insects 6.1
    • Gene flow 6.2
    • Food 6.3
    • Starlink corn recalls 6.4
    • Corporate espionage 6.5
  • See also 7
  • References 8
  • External links 9

Marketed products

Herbicide resistant maize

Corn varieties resistant to glyphosate herbicides were first commercialized in 1996 by Monsanto, and are known as "Roundup Ready Corn". They tolerate the use of Roundup.[1] Bayer CropScience developed "Liberty Link Corn" that is resistant to glufosinate.[2] Pioneer Hi-Bred has developed and markets corn hybrids with tolerance to imidazoline herbicides under the trademark "Clearfield" - though in these hybrids, the herbicide-tolerance trait was bred using tissue culture selection and the chemical mutagen ethyl methanesulfonate not genetic engineering.[3] Consequently, the regulatory framework governing the approval of transgenic crops does not apply for Clearfield.[3]

As of 2011, herbicide-resistant GM corn was grown in 14 countries.[4] By 2012, 26 varieties herbicide-resistant GM maize were authorised for import into the European Union.,[5] but such imports remain controversial.[6] Cultivation of herbicide-resistant corn in the EU provides substantial farm-level benefits.[7]

Insecticide-producing corn

The European corn borer, Ostrinia nubilalis, destroys corn crops by burrowing into the stem, causing the plant to fall over.

Bt corn is a variant of

  • GMO Safety - Overview on biosafety research projects on genetically modified maize funded by the Federal Ministry of Education and Research (BMBF)
  • Co-Extra - research project on coexistence and traceability of GM and non-GM supply chains
  • EFSA GMO Panel deliberations on the Austrian report "Biological effects of transgenic maize NK603 x MON 810 fed in long term reproduction studies in mice" (Part of the minutes of the plenary meeting held on 3–4 December 2008, see on page 9)

External links

  1. ^
  2. ^
  3. ^ a b
  4. ^
  5. ^ Staff EU register of genetically modified food and feed European Commission, Health and Consumers, EU register of authorised GMOs, Retrieved 26 August 2012
  6. ^ Hogan, Michael (5 April 2012) BASF to undertake GMO potato trials in Europe Reuters Edition US, Accessed 26 August 2012
  7. ^ Wesseler, J., S. Scatasta, E. Nillesen (2007): The Maximum Incremental Social Tolerable Irreversible Costs (MISTICs) and other Benefits and Costs of Introducing Transgenic Maize in the EU-15. Pedobiologia 51(3):261-269
  8. ^ a b
  9. ^
  10. ^ Ostlie KR et al. University of Minnesota Extension Office. Last Reviewed 2008. Bt Corn & European Corn Borer: Long-Term Success Through Resistance Management
  11. ^ Marra, M.C., Piggott, N.E., & Goodwin, B.K. (2012). The impact of corn rootworm protected biotechnology traits in the United States. AgBioForum, 15(2), 217-230
  12. ^ Erin W. Hodgson, Utah State University Extension and Utah Plant Pest Diagnostic Laboratory. Western corn rootworm
  13. ^ W.S. Cranshaw, Colorado State University Extension Office. Last updated March 26, 2013. Bacillus thuringiensis Fact Sheet
  14. ^ Hellmich, R. L. & Hellmich, K. A. (2012) Use and Impact of Bt Maize. Nature Education Knowledge 3(10):4
  15. ^ Ric Bessin, Extension Entomologist, University of Kentucky College of Agriculture. May 1996, last updated November 2010. Bt-Corn for Corn Borer Control
  16. ^ Castagnola AS, Jurat-Fuentes, JL. Bt Crops: Past and Future. Chapter 15 in [Bacillus Thuringiensis Biotechnology], Ed. Estibaliz Sansinenea. Springer, Mar 2, 2012
  17. ^ Erin Hodgson and Aaron Gassmann, Iowa State Extension, Department of Entomology. May 2010. New Corn Trait Deregulated in U.S.
  18. ^ OECD BioTrack Database. MON87460
  19. ^ Federal Register, Vol. 76, No. 248, December 27, 2011.
  20. ^ Michael Eisenstein Plant breeding: Discovery in a dry spell Nature 501, S7–S9 (26 September 2013) Published online 25 September 2013
  21. ^ Syngenta Sweet Corn Products
  22. ^ [1]
  23. ^
  24. ^ a b c
  25. ^
  26. ^ a b
  27. ^
  28. ^
  29. ^ Staff, University of Minnesota Extension. Section: Can European corn borer develop resistance to Bt corn? in the Bt Corn & European Corn Borer
  30. ^
  31. ^
  32. ^
  33. ^ Jack Kaskey for Bloomberg News Nov 16, 2012 DuPont-Dow Corn Defeated by Armyworms in Florida: Study
  34. ^ Wesseler, J. and N. Kalaitzandonakes (2011): Present and Future EU GMO policy. In Arie Oskam, Gerrit Meesters and Huib Silvis (eds.), EU Policy for Agriculture, Food and Rural Areas. Second Edition, pp. 23-323 – 23-332. Wageningen: Wageningen Academic Publishers
  35. ^ Beckmann, V., C. Soregaroli, J. Wesseler (2011): Coexistence of genetically modified (GM) and non-modified (non GM) crops: Are the two main property rights regimes equivalent with respect to the coexistence value? In "Genetically modified food and global welfare" edited by Colin Carter, GianCarlo Moschini and Ian Sheldon, pp 201-224. Volume 10 in Frontiers of Economics and Globalization Series. Bingley, UK: Emerald Group Publishing
  36. ^ American Association for the Advancement of Science (AAAS), Board of Directors (2012). Legally Mandating GM Food Labels Could Mislead and Falsely Alarm Consumers
  37. ^
  38. ^
  39. ^ American Medical Association (2012). Report 2 of the Council on Science and Public Health: Labeling of Bioengineered Foods
  40. ^ FAO, 2004. State of Food and Agriculture 2003–2004. Agricultural Biotechnology: Meeting the Needs of the Poor. Food and Agriculture Organization of the United Nations, Rome. "Currently available transgenic crops and foods derived from them have been judged safe to eat and the methods used to test their safety have been deemed appropriate. These conclusions represent the consensus of the scientific evidence surveyed by the ICSU (2003) and they are consistent with the views of the World Health Organization (WHO, 2002). These foods have been assessed for increased risks to human health by several national regulatory authorities (inter alia, Argentina, Brazil, Canada, China, the United Kingdom and the United States) using their national food safety procedures (ICSU). To date no verifiable untoward toxic or nutritionally deleterious effects resulting from the consumption of foods derived from genetically modified crops have been discovered anywhere in the world (GM Science Review Panel). Many millions of people have consumed foods derived from GM plants - mainly maize, soybean and oilseed rape - without any observed adverse effects (ICSU)."
  41. ^ Other sources:
    • World Health Organization. Food safety: 20 questions on genetically modified foods. Accessed December 22, 2012.
    • United States Institute of Medicine and National Research Council (2004). Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects. National Academies Press. Free full-text. National Academies Press. See pp11ff on need for better standards and tools to evaluate GM food.
    • Tamar Haspel for the Washington Post. October 15, 2013. Genetically modified foods: What is and isn’t true
    • Winter CK and Gallegos LK (2006). Safety of Genetically Engineered Food. University of California Agriculture and Natural Resources Communications, Publication 8180.
    • Dr. Christopher Preston, AgBioWorld 2011. Peer Reviewed Publications on the Safety of GM Foods.
  42. ^
  43. ^
  44. ^
  45. ^ a b
  46. ^ Andrew Pollack for the New York Times. April 13, 2010 Study Says Overuse Threatens Gains From Modified Crops
  47. ^
  48. ^
  49. ^ Wesseler, J. (ed.) (2005): Environmental Costs and Benefits of Transgenic Crops. Dordrecht, NL: Springer Press
  50. ^
  51. ^ Dorsch, J.A. et al. Cry1a Toxins of Bacillus Thuringiensis Bind Specifically to a Region Adjacent to the Membrane-Proximal Extracellular Domain of Bt-R-1 in Manduca Sexta: Involvement of a Cadherin in the Entomopathogenicity of Bacillus Thuringiensis. Insect Biochemistry and Molecular Biology 32, 1025-1036 (2002)
  52. ^
  53. ^
  54. ^ Losey JE et al. (1999) Transgenic pollen harms monarch larvae. Nature 399: 214
  55. ^
  56. ^
  57. ^
  58. ^
  59. ^
  60. ^
  61. ^ GMO Compass. 5 June 2009 Mexico: controlled cultivation of genetically modified maize
  62. ^ Mike Shanahan for Science and Development Network, 10 November 2004. Warning issued on GM maize imported to Mexico - SciDev.Net
  63. ^ Katie Mantell for Science and Development Network, 30 November 2001 GM maize found ‘contaminating’ wild strains - SciDev.Net
  64. ^
  65. ^
  66. ^
  67. ^
  68. ^
  69. ^
  70. ^ EFSA Minutes of the 55th Plenary Meeting of the Scientific Panel on Genetically Mofified Organisms Held on 27-28 January 2010 IN Parma, Italy, Annex 1, Vendemois et al. 2009 European Food Safety Authority report, Retrieved 27 July 2012
  71. ^
  72. ^
  73. ^ Alain de Weck: Une protéine pesticide OGM (Cry1ab) dans le sang de femmes gravides et de leur fœtus? Un travail bâclé et un scénario catastrophe très probablement inexistant
  74. ^
  75. ^
  76. ^
  77. ^
  78. ^ a b c d Michael R. Taylor and Jody S. Tick of Resources for the Future, Pew Initiative on Food and Biotechnology. The StarLink Case: Issues for the Future
  79. ^ "While EPA had no specific data to indicate that Cry9C was an allergen, the protein expressed in StarLink corn did exhibit certain characteristics (i.e. relative heat stability and extended time to digestion) that were common to known food allergens such as those found in peanuts, eggs, etc. EPA’s concern was that StarLink corn may be a human food allergen and in the absence of more definitive data, EPA has not made a decision whether or not to register the human food use." Staff, EPA. November 2000 Executive Summary: EPA Preliminary Evaluation of Information Contained in the October 25, 2000 Submission from Aventis Cropscience
  80. ^ Plant Genetic Systems (America) Inc.: PP 7G4921 Federal Register Vol. 62, No. 228, November 26, 1997 pp 63169 bottom of middle column - 63170 right column; see especially p63169 top of right column
  81. ^ King D, Gordon A. Contaminant found in Taco Bell taco shells. Food safety coalition demands recall (press release), vol 2001. Washington, DC: Friends of the Earth, 2000. 3 November 2001.
  82. ^
  83. ^ Agricultural Biotechnology: Updated Benefit Estimates, Janet E. Carpenter and Leonard )P. Gianessi 2001, National Center for Food and Agricultural Policy
  84. ^ Staff, EPA review committee. LLP Incidents
  85. ^
  86. ^ FIFRA Scientific Advisory Panel Report No. 2001-09, July 2001
  87. ^
  88. ^
  89. ^


See also

On December 19, 2013 six Chinese citizens were indicted in Iowa on charges of plotting to steal genetically modified seeds worth tens of millions of dollars from Monsanto and DuPont. Mo Hailong, director of international business at the Beijing Dabeinong Technology Group Co., part of the Beijing-based DBN Group, was accused of stealing trade secrets after he was found digging in an Iowa cornfield.[90]

Corporate espionage

In 2005, aid sent by the UN and the US to Central American nations also contained some StarLink corn. The nations involved, Nicaragua, Honduras, El Salvador and Guatemala refused to accept the aid.[89]

The US corn supply has been monitored for the presence of the Starlink Bt proteins since 2001.[88]

A subsequent review of these tests by the Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel points out that while "the negative results decrease the probability that the Cry9C protein is the cause of allergic symptoms in the individuals examined ... in the absence of a positive control and questions regarding the sensitivity and specificity of the assay, it is not possible to assign a negative predictive value to this."[87]

Fifty-one people reported adverse effects to the FDA; US Centers for Disease Control (CDC), which determined that 28 of them were possibly related to Starlink.[85] However, the CDC studied the blood of these 28 individuals and concluded there was no evidence of hypersensitivity to the Starlink Bt protein.[86]

StarLink corn was subsequently found in food destined for consumption by humans in the US, Japan, and South Korea.[79]:20–21 This corn became the subject of the widely publicized Starlink corn recall, which started when Taco Bell-branded taco shells sold in supermarkets were found to contain the corn. Sales of StarLink seed were discontinued.[82][83] The registration for Starlink varieties was voluntarily withdrawn by Aventis in October 2000. (Pioneer had been bought by AgrEvo which then became Aventis CropScience at the time of the incident,[79]:15–16 which was later bought by Bayer[84]

StarLink contains Cry9C, which had not previously been used in a GM crop.[78] Starlink's creator, Plant Genetic Systems had applied to the US Environmental Protection Agency (EPA) to market Starlink for use in animal feed and in human food.[79]:14 However, because the Cry9C protein lasts longer in the digestive system than other Bt proteins, the EPA had concerns about its allergenicity, and PGS did not provide sufficient data to prove that Cry9C was not allergenic.[80]:3 As a result PGS split its application into separate permits for use in food and use in animal feed.[78][81] Starlink was approved by the EPA for use in animal feed only in May 1998.[79]:15

Starlink corn recalls

In January 2013, the European Food Safety Authority released all data submitted by Monsanto in relation to the 2003 authorisation of maize genetically modified for glyphosate tolerance.[77]

A 2011 Canadian study looked at the presence of CryAb1 protein (BT toxin) in non-pregnant women, pregnant women and fetal blood. All groups had detectable levels of the protein, including 93% of pregnant women and 80% of fetuses at concentrations of 0.19 ± 0.30 and 0.04 ± 0.04 mean ± SD ng/ml, respectively.[72] The paper did not discuss safety implications or find any health problems. The paper was found to be unconvincing by multiple authors and organizations.[73][74][75] In a swine model, Cry1Ab-specific antibodies were not detected in pregnant sows or their offspring and no negative effects from feeding Bt maize to pregnant sows were observed.[76]

A review by Food Standards Australia New Zealand and others of the same study concluded that the results were due to chance alone.[70][71]

The French High Council of Biotechnologies Scientific Committee reviewed the 2009 Vendômois et al. study and concluded that it "..presents no admissible scientific element likely to ascribe any haematological, hepatic or renal toxicity to the three re-analysed GMOs."[69] However, the French government applies the precautionary principle with respect to GMOs.


A 2004 study found Bt protein in kernels of refuge corn.[68]

In 2009 the government of Mexico created a regulatory pathway for genetically modified maize,[61] but because Mexico is the center of diversity for maize, gene flow could affect a large fraction of the world's maize strains.[62][63] A 2001 report in Nature presented evidence that Bt maize was cross-breeding with unmodified maize in Mexico.[64] The data in this paper was later described as originating from an artifact. Nature later stated, "the evidence available is not sufficient to justify the publication of the original paper".[65] A 2005 large-scale study failed to find any evidence of contamination in Oaxaca.[66] However, other authors also found evidence of cross-breeding between natural maize and transgenic maize.[67]

Gene flow is the transfer of genes and/or alleles from one species to another. Concerns focus on the interaction between GM and other maize varieties in Mexico, and of gene flow into refuges.

Gene flow

A 1999 study found that in a lab environment, pollen from Bt maize dusted onto milkweed could harm the monarch butterfly.[54][55] Several groups later studied the phenomenon in both the field and the laboratory, resulting in a risk assessment that concluded that any risk posed by the corn to butterfly populations under real-world conditions was negligible.[56] A 2002 review of the scientific literature concluded that "the commercial large-scale cultivation of current Bt–maize hybrids did not pose a significant risk to the monarch population".[57][58][59] A 2007 review found that "nontarget invertebrates are generally more abundant in Bt cotton and Bt maize fields than in nontransgenic fields managed with insecticides. However, in comparison with insecticide-free control fields, certain nontarget taxa are less abundant in Bt fields."[60]

[53][52] proteins are toxic towards the insect orders cyt While [8] Critics claim that Bt proteins could target predatory and other beneficial or harmless insects as well as the targeted pest. These proteins have been used as organic sprays for insect control in France since 1938 and the USA since 1958 with no ill effects on the environment reported.

Effects on nontarget insects

Critics have objected to GM crops on ecological, economic and health grounds. The economic issues derive from those organisms that are subject to intellectual property law, mostly patents. The first generation of GM crops lose patent protection beginning in 2015. Monsanto has claimed it will not to pursue farmers who retain seeds of off-patent varieties.[48] These controversies have led to litigation, international trade disputes, protests and to restrictive legislation in most countries.[49]

GM crops provide a number of ecological benefits, but there are also concerns for their overuse, stalled research outside of the Bt seed industry, proper management and issues with Bt resistance arising from their misuse.[45][46][47]

Broad scientific consensus holds that food derived from GM crops poses no greater risk to human health than conventional food.[36][37][38][39][40][41] The scientific rigor of the studies regarding human health has been disputed due to alleged lack of independence and due to conflicts of interest involving governing bodies and some of those who perform and evaluate the studies.[42][43][44][45]


Regulation of GM crops varies between countries, with some of the most-marked differences occurring between the USA and Europe. Regulation varies in a given country depending on intended uses.[34][35]


In November 2009, Monsanto scientists found the pink bollworm had become resistant to first-generation Bt cotton in parts of Gujarat, India - that generation expresses one Bt gene, Cry1Ac. This was the first instance of Bt resistance confirmed by Monsanto anywhere in the world.[30][31] Bollworm resistance to first generation Bt cotton has been identified in the Australia, China, Spain and the United States.[32] In 2012, a Florida field trial demonstrated that army worms were resistant to pesticide-containing GM corn produced by Dupont-Dow; armyworm resistance was first discovered in Puerto Rico in 2006, prompting Dow and DuPont to voluntarily stop selling the product on the island.[33]

Resistant strains of the European corn borer have developed in areas with defective or absent refuge management.[26][29]


Seed bags containing both Bt and refuge seed have been approved by the EPA in the United States. These seed mixtures were marketed as "Refuge in A Bag" (RIB) to increase farmer compliance with refuge requirements and reduce additional work needed at planting from having separate Bt and refuge seed bags on hand. The EPA approved a lower percentage of refuge seed in these seed mixtures ranging from 5 to 10%. This strategy is likely to reduce the likelihood of Bt-resistance occurring for corn rootworm, but may increase the risk of resistance for lepidopteran pests, such as European corn borer. Increased concerns for resistance with seed mixtures include partially resistant larvae on a Bt plant being able to move to a susceptible plant to survive or cross pollination of refuge pollen on to Bt plants that can lower the amount of Bt expressed in kernels for ear feeding insects.[27][28]

Unmodified crops received most of the economic benefits of Bt corn in the US in 1996-2007, because of the overall reduction of pest populations. This reduction came because females laid eggs on modified and unmodified strains alike.[26]

The theory behind these refuges is to slow the evolution of resistance to the pesticide. EPA regulations also require seed companies to train farmers how to maintain refuges, to collect data on the refuges and to report that data to the EPA.[24] A study of these reports found that from 2003 to 2005 farmer compliance with keeping refuges was above 90%, but that by 2008 approximately 25% of Bt corn farmers did not keep refuges properly, raising concerns that resistance would develop.[24]

US Environmental Protection Agency (EPA) regulations require farmers who plant Bt corn to plant non-Bt corn nearby (called a "refuge") to provide a location to harbor vulnerable pests.[24] Typically, 20% of corn in a grower's fields must be refuge; refuge must be at least 0.5 miles from Bt corn for lepidopteran pests, and refuge for corn rootworm must at least be adjacent to a Bt field.[25]


In 2007, South African researchers announced the production of transgenic maize resistant to maize streak virus (MSV), although it has not been released as a product.[23]

Products in development

GM sweet corn varieties include "Attribute", the brand name for insect-resistant sweet corn developed by Syngenta.[21] and Performance Series™ insect-resistant sweet corn developed by Monsanto. [22]

Sweet corn

In 2013 Monsanto launched the first transgenic drought tolerance trait in a line of corn hybrids called DroughtGard.[18] The MON 87460 trait is provided by the insertion of the cspB gene from the soil microbe Bacillus subtilis; it was approved by the USDA in 2011[19] and by China in 2013.[20]

Drought resistance

Approved Bt genes include single and stacked (event names bracketed) configurations of: Cry1A.105 (MON89034), CryIAb (MON810), CryIF (1507), Cry2Ab (MON89034), Cry3Bb1 (MON863 and MON88017), Cry34Ab1 (59122), Cry35Ab1 (59122), mCry3A (MIR604), and Vip3A (MIR162), in both corn and cotton.[15][16]:285ff Corn genetically modified to produce VIP was first approved in the US in 2010.[17]

In 1996, the first GM maize producing a Bt Cry protein was approved, which killed the European corn borer and related species; subsequent Bt genes were introduced that killed corn rootworm larvae.[14]

The Bt protein is expressed throughout the plant. When a vulnerable insect eats the Bt-containing plant, the protein is activated in its gut, which is alkaline. In the alkaline environment the protein partially unfolds and is cut by other proteins, forming a toxin that paralyzes the insect's digestive system and forms holes in the gut wall. The insect stops eating within a few hours and eventually starves.[13]

In recent years, traits have been added to ward off Corn ear worms and root worms, the latter of which annually causes about a billion dollars in damages.[11][12]

[10] causes about a billion dollars in damage to corn crops each year.European corn borer The [9]

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