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Genetically modified maize
Genetically modified maize
Genetically modified maize
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Genetic engineering
 
Genetically modified organisms
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Transgenic maize containing a gene from the bacteria Bacillus thuringiensis

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

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Herbicide-resistant maize

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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 of 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]

Insect-resistant corn

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

Bt maize/corn

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Bt maize/Bt corn is a variant of maize that has been genetically altered to express one or more proteins from the bacterium Bacillus thuringiensis[8] including Delta endotoxins. The protein is poisonous to certain insect pests. Spores of the bacillus are widely used in organic gardening,[9] although GM corn is not considered organic. The European corn borer causes about a billion dollars in damage to corn crops each year.[10]

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]

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][14]

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.[15]

The Philippine Government has promoted Bt corn, hoping for insect resistance and higher yields.[16]

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.[17][18]: 285ff  Corn genetically modified to produce VIP was first approved in the US in 2010.[19]

A 2018 study found that Bt-corn protected nearby fields of non-Bt corn and nearby vegetable crops, reducing the use of pesticides on those crops. Data from 1976 to 1996 (before Bt corn was widespread) was compared to data after it was adopted (1996–2016). They examined levels of the European corn borer and corn earworm. Their larvae eat a variety of crops, including peppers and green beans. Between 1992 and 2016, the amount of insecticide applied to New Jersey pepper fields decreased by 85 percent. Another factor was the introduction of more effective pesticides that were applied less often.[20]

Sweet Corn

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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]

Cuba

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While Cuba's agriculture is largely focused on organic production, as of 2010, the country had developed a variety of genetically modified corn that is resistant to the palomilla moth.[23]

Drought-resistant maize

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In 2013 Monsanto launched the first transgenic drought tolerance trait in a line of corn hybrids called DroughtGard.[24] 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[25] and by China in 2013.[26]

Health Safety

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In regular corn crops, insects promote fungal colonization by creating "wounds," or holes, in corn kernels. These wounds are favored by fungal spores for germination, which subsequently leads to mycotoxin accumulation in the crop that can be carcinogenic and toxic to humans and other animals. This can prove to be especially devastating in developing countries with drastic climate patterns such as high temperatures, which favor the development of toxic fungi. In addition, higher mycotoxin levels leads to market rejection or reduced market prices for the grain. GM corn crops encounter fewer insect attacks, and thus, have lower concentrations of mycotoxins. Fewer insect attacks also keep corn ears from being damaged, which increases overall yields.[27]

Products in development

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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.[28] While breeding cultivars for resistance to MSV isn't done in the public, the private sector, international research centers, and national programmes have done all of the breeding.[29] As of 2014, there have been a few MSV-tolerant cultivars released in Africa. A private company Seedco has released 5 MSV cultivars.[30]

Research has been done on adding a single E. coli gene to maize to enable it to be grown with an essential amino acid (methionine).[31][32]

Refuges

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US Environmental Protection Agency (EPA) regulations require farmers who plant Bt corn to plant non-Bt corn nearby (called a refuge), with the logic that pests will infest the non-Bt corn and thus will not evolve a resistance to the Bt toxin.[33] 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.[34] 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.[33] 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.[33]

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, but pest organisms that develop on the modified strain are eliminated.[35]

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.[36][37]

Resistance

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Resistant strains of the European corn borer have developed in areas with defective or absent refuge management.[35][33] In 2012, a Florida field trial demonstrated that army worms were resistant to Bt maize 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.[38]

Regulation

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Main article: Regulation of the release of genetic modified organisms

Regulation of GM crops varies between countries, with some of the most-marked differences occurring between the US and Europe. Regulation varies in a given country depending on intended uses.[39][40]

Controversy

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Main article: Genetically modified food controversies

There is a scientific consensus[41][42][43][44] that currently available food derived from GM crops poses no greater risk to human health than conventional food,[45][46][47][48][49] but that each GM food needs to be tested on a case-by-case basis before introduction.[50][51][52] Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe.[53][54][55][56] The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation.[57][58][59][60]

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.[61][62][63][64] However, no reports of ill effects from GM food have been documented in the human population.[65][66][67]

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.[64][68][69]

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 pursue farmers who retain seeds of off-patent varieties.[70] These controversies have led to litigation, international trade disputes, protests and to restrictive legislation in most countries.[71]

Introduction of Bt maize led to significant reduction of mycotoxin-related poisoning and cancer rates, as they were significantly less prone to contain mycotoxins (29%), fumonisins (31%) and thricotecens (37%), all of which are toxic and carcinogenic.[72]

Effects on nontarget insects

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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.[8] While cyt proteins are toxic towards the insect order Diptera (flies), certain cry proteins selectively target lepidopterans (moths and butterflies), while other cyt selectively target Coleoptera.[73] As a toxic mechanism, cry proteins bind to specific receptors on the membranes of mid-gut (epithelial) cells, resulting in rupture of those cells. Any organism that lacks the appropriate gut receptors cannot be affected by the cry protein, and therefore Bt.[74][75] Regulatory agencies assess the potential for the transgenic plant to impact nontarget organisms before approving commercial release.[76][77]

A 1999 study found that in a lab environment, pollen from Bt maize dusted onto milkweed could harm the monarch butterfly.[78][79] 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.[80] 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".[81][82][83] 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."[84]

Gene flow

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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.

In 2009 the government of Mexico created a regulatory pathway for genetically modified maize,[85] but because Mexico is the center of diversity for maize, gene flow could affect a large fraction of the world's maize strains.[86][87] A 2001 report in Nature presented evidence that Bt maize was cross-breeding with unmodified maize in Mexico.[88] 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".[89] A 2005 large-scale study failed to find any evidence of contamination in Oaxaca.[90] However, other authors also found evidence of cross-breeding between natural maize and transgenic maize.[91]

A 2004 study found Bt protein in kernels of refuge corn.[92]

In 2017, a large-scale study found "pervasive presence of transgenes and glyphosate in maize-derived food in Mexico"[93]

Food

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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."[94] However, the French government applies the precautionary principle with respect to GMOs.[95][96][97]

A review by Food Standards Australia New Zealand and others of the same study concluded that the results were due to chance alone.[98][99]

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.[100] The paper did not discuss safety implications or find any health problems. FSANZ agency published a comment pointing out a number of inconsistencies in the paper, most notably that it "does not provide any evidence that GM foods are the source of the protein".[101]

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.[102]

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Main article: Starlink corn recall

StarLink contains Cry9C, which had not previously been used in a GM crop.[103] 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.[104]: 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.[105]: 3  As a result, PGS split its application into separate permits for use in food and use in animal feed.[103][106] Starlink was approved by the EPA for use in animal feed only in May 1998.[104]: 15 

StarLink corn was subsequently found in food destined for consumption by humans in the US, Japan, and South Korea.[104]: 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.[107][108] 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,[104]: 15–16  which was later bought by Bayer.[109]

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.[110] However, the CDC studied the blood of these 28 individuals and concluded there was no evidence of hypersensitivity to the Starlink Bt protein.[111]

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."[112]

The US corn supply has been monitored for the presence of the Starlink Bt proteins since 2001.[113]

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.[114]

Corporate espionage

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On 19 December 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.[115]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Genetically modified maize

View on Grokipedia
from Grokipedia
Genetically modified maize refers to varieties of corn (Zea mays) engineered via recombinant DNA technology primarily to confer resistance to insects, such as the European corn borer, or tolerance to herbicides like glyphosate. Commercialization began in the mid-1990s, with the first herbicide-tolerant and insect-resistant strains approved for planting in 1996, rapidly expanding to dominate global production due to enhanced agronomic performance. In the United States, where maize is a staple crop, adoption rates exceed 90% of planted acreage for varieties incorporating these traits, enabling higher yields—averaging 22% increases—and substantial reductions in insecticide applications by 37%, as evidenced by comprehensive meta-analyses of field trials. These benefits extend to decreased mycotoxin contamination from pests and lower farmer exposure to chemicals, supporting sustainable intensification amid growing food demands. Rigorous assessments by bodies like the National Academy of Sciences conclude that GM maize is as safe for human consumption and the environment as conventional counterparts, with no validated evidence of unique health risks or significant non-target effects after decades of scrutiny and billions of tons consumed. Persistent controversies, often amplified by advocacy groups despite contradictory empirical data from peer-reviewed studies, center on unsubstantiated fears of allergenicity, gene flow, or monopolistic seed practices, yet regulatory approvals and long-term monitoring affirm their overall safety and efficacy.

History

Early research and development

The initial attempts to genetically transform maize (Zea mays) date to 1966, when researchers Coe and Sarkar injected genomic DNA from purple maize into immature kernels and apical meristems of white plants, observing transient pigmentation changes but no stable integration or . Subsequent efforts in the 1970s focused on establishing systems essential for regeneration, with Green and Phillips in 1975 achieving plant regeneration from inbred line A188 protoplasts, laying groundwork for later genetic manipulation. By 1985, Armstrong and Green developed friable, embryogenic Type II cultures using L-proline supplementation, which proved highly responsive to transformation due to their totipotent nature, contrasting with less regenerable Type I calli. The late 1980s marked a surge in DNA delivery techniques, as maize's recalcitrance to Agrobacterium-mediated transformation—due to its monocot —necessitated alternative methods. In 1986, Fromm et al. reported stable nptII gene integration via of Black Mexican Sweet suspension culture protoplasts, though plants were non-regenerable. That same year, Ohta demonstrated pollen-mediated uptake of exogenous DNA, achieving reported high-efficiency transformation. Particle bombardment emerged as a breakthrough: Klein et al. in 1988 successfully delivered plasmid DNA encoding selectable (nptII) and screenable markers into intact maize suspension cells and Black Mexican Sweet protoplasts using high-velocity microprojectiles, confirming transient via GUS assays. Rhodes et al. also achieved stable transformation of protoplasts that year, regenerating calli with integrated genes. Stable, fertile transgenic maize plants were first realized in 1990 through biolistic methods on embryogenic cultures. Fromm et al. bombarded SC82 and SC719 genotypes, recovering kanamycin-resistant, fertile R0 plants transmitting the bar herbicide-resistance to progeny at Mendelian ratios. Independently, Gordon-Kamm et al. used microprojectile bombardment on Type II calli from elite inbreds like A188 × B73, integrating selectable markers and regenerating fertile plants with stable inheritance. These milestones overcame maize's regeneration barriers, enabling targeted trait insertion, though efficiencies remained low (typically <1%) and genotype-dependent, spurring refinements in selectable markers and promoters for broader applicability.

Commercial introduction in the 1990s

The commercial introduction of genetically modified maize began in the United States in 1996, following regulatory approvals for insect-resistant varieties engineered to produce (Bt) δ-endotoxins targeting lepidopteran pests like the European corn borer. The U.S. Environmental Protection Agency (EPA) approved Monsanto's YieldGard corn (MON 810 event) in 1995, enabling commercial planting the following year, which marked the first widespread adoption of GM maize hybrids. These varieties incorporated the cry1Ab gene from Bt kurstaki, conferring resistance without the need for broad-spectrum insecticides, and were deregulated by the U.S. Department of Agriculture (USDA) after field trials demonstrated efficacy and safety. In parallel, early herbicide-tolerant maize lines emerged toward the late 1990s, with Novartis (now ) introducing LibertyLink maize tolerant to glufosinate in 1997, followed by Monsanto's glyphosate-tolerant varieties approved for commercial use in 1998. These traits allowed post-emergence herbicide application, simplifying weed control and integrating with no-till farming practices. Initial planting of GM maize in 1996 covered approximately 1 million hectares in the U.S., representing about 15% of total corn acreage, with rapid expansion driven by yield benefits and reduced pest management costs. By the end of the decade, stacked traits combining Bt insect resistance and herbicide tolerance began entering the market, such as Monsanto's YieldGard Plus in 1999, further accelerating adoption rates to over 25% of U.S. corn acreage. Commercial releases were initially confined to North America, with approvals in Canada mirroring the U.S. timeline, while European and other regions lagged due to stricter regulatory hurdles. Empirical data from early adoption showed yield increases of 5-10% in Bt maize fields under high pest pressure, supporting the technology's economic viability without evidence of widespread ecological disruption in initial assessments.

Expansion and adoption post-2000

The adoption of genetically modified maize accelerated markedly after 2000, as farmers in major producing regions selected varieties offering insect resistance, herbicide tolerance, and later stacked traits for improved yields and reduced production costs. In the United States, where GM maize was first commercialized, insect-resistant Bt varieties occupied 19% of corn acreage in 2000, rising to 52% by 2010 and 86% by 2024; herbicide-tolerant varieties increased from 34% in 2000 to 91% by 2023, with stacked traits dominating over 80% of plantings by the mid-2010s. This trend extended to South America, where Argentina approved insect-resistant maize in 1998 and achieved widespread adoption equivalent to levels that conventional hybrids took 27 years to reach, within just 13 years. Brazil authorized commercial GM maize planting in 2008, with adoption surpassing 80% of its maize area by 2013 and stabilizing above 88% through 2023, driven by farmer demand for traits addressing regional pest pressures and weed challenges. Paraguay followed suit, reaching 80% GM maize adoption by 2023. Globally, GM maize planted area expanded from approximately 10 million hectares in the early 2000s to 68.4 million hectares by 2023, representing over half of total maize cultivation in adopting countries and comprising the second-largest GM crop category after soybeans. The United States accounted for the largest share at 34.8 million hectares in 2024, or 50.9% of the global total, followed by Brazil and Argentina as key contributors to hemispheric growth. Stacked events integrating multiple traits became standard by the 2010s, facilitating further uptake amid rising demand for efficient crop protection without proportional increases in chemical inputs. Regulatory approvals proliferated, with over 200 maize events authorized worldwide by 2023, enabling tailored varieties for diverse agroecological zones.

Genetic Engineering Methods

Transformation techniques for maize

Particle bombardment, or biolistics, represents the earliest and historically dominant technique for maize transformation, involving the acceleration of DNA-coated microprojectiles—typically gold or tungsten particles—into target plant cells using a gene gun device. This physical method bypasses biological barriers to DNA delivery and was first demonstrated to achieve transient gene expression in intact maize suspension culture cells in 1989, followed by stable transformation of embryogenic callus in 1990, enabling the recovery of fertile transgenic plants expressing selectable marker genes like bar for herbicide resistance. Biolistics has facilitated the commercial development of numerous GM maize varieties, particularly through bombardment of immature embryos or friable embryogenic callus derived from elite inbred lines, though it often results in multiple transgene copies and potential rearrangements due to random integration. Transformation efficiencies via biolistics vary by genotype and protocol but typically range from 1% to 10% in optimized systems, with osmotic treatments or tissue preconditioning enhancing DNA uptake and stable event recovery. Agrobacterium tumefaciens-mediated transformation, leveraging the bacterium's natural T-DNA transfer mechanism, emerged as a complementary approach for maize in the mid-1990s after overcoming monocot-specific barriers through superbinary vectors, acetosyringone induction of virulence genes, and use of immature zygotic embryos as explants. This method was first reported to yield efficient, low-copy-number transgenic events in the maize inbred A188 in 1996, with protocols co-cultivating embryos for 2-3 days to promote T-DNA integration via the host's wound-response pathways. Agrobacterium offers advantages in producing cleaner integration sites compared to biolistics, reducing silencing risks, and has become preferred for stacking multiple traits in commercial pipelines, achieving efficiencies of 4-20% in responsive temperate genotypes like B104, though tropical lines often require further optimization such as sonication-assisted or hydroxyproline-rich glycoprotein enhancements. Both techniques rely on subsequent tissue culture regeneration via somatic embryogenesis, with immature embryos (10-14 days post-pollination) as the standard target due to their totipotency, though direct immature embryo systems minimize somaclonal variation. Emerging refinements include baby boom (Bbm) and Wuschel2 (Wus2) morphogenic genes to enable transformation without prolonged callus phases, shortening timelines to 8-12 weeks and broadening genotype applicability beyond highly responsive lines. Other physical methods like electroporation of protoplasts or pollen have been explored but remain less efficient and non-routine for stable maize transgenics. Protocol success hinges on factors including explant quality, selectable agents (e.g., phosphinothricin or hygromycin), and vector design, with peer-reviewed advancements emphasizing genotype-independent tools to accelerate trait deployment in diverse maize germplasm.

Key genes and traits engineered

The primary genes engineered into maize (Zea mays) confer traits such as insect resistance, herbicide tolerance, and abiotic stress tolerance, enabling targeted agronomic improvements. Insect resistance typically involves cry genes derived from Bacillus thuringiensis (Bt), which encode delta-endotoxins that disrupt insect midgut function upon ingestion, specifically targeting lepidopteran pests like the European corn borer (Ostrinia nubilalis) and fall armyworm (Spodoptera frugiperda). For instance, the cry1Ab gene in event MON810 produces Cry1Ab protein, providing protection against above-ground lepidopteran larvae. Similarly, cry1F expresses Cry1F protein effective against corn earworm (Helicoverpa zea) and southwestern corn borer (Diatraea grandiosella), though efficacy against some pests like western bean cutworm has declined over time due to resistance evolution. Herbicide tolerance is predominantly achieved through modifications to the epsps gene, which encodes 5-enolpyruvylshikimate-3-phosphate synthase, an enzyme in the shikimate pathway targeted by glyphosate. The bacterial cp4 epsps gene from Agrobacterium sp. strain CP4 produces a glyphosate-insensitive variant, as in Roundup Ready maize events like NK603, allowing post-emergence application of glyphosate for broad-spectrum weed control without crop damage. Alternative variants include mepsps (maize-optimized EPSPS) in event GA21 and dgt-28 epsps from Streptomyces sviceus in events like DAS-ز625-8, which confer tolerance via prokaryotic EPSPS enzymes with altered binding affinity. Overexpression of codon-optimized epsps alleles, such as TIPS-OsEPSPS under the ZmUbi promoter, has demonstrated up to threefold tolerance to recommended glyphosate doses in field trials. Abiotic stress tolerance, particularly drought, involves genes like cspB from Bacillus subtilis in event MON87460 (DroughtGard), which encodes cold shock protein B to stabilize cellular processes, RNA chaperoning, and membrane protection under water-limited conditions, resulting in yield preservation during severe drought episodes. This trait integrates with selectable markers like nptII (neomycin phosphotransferase II) for transformation efficiency, though the primary agronomic benefit stems from cspB expression. Stacked constructs often combine these genes, such as cry1A.105 with cry3Bb1 for dual lepidopteran and coleopteran (e.g., corn rootworm) resistance in events like MON88017, or cry1Ab/cry1Ac fusions for broadened spectrum activity. These modifications are introduced via Agrobacterium-mediated transformation or particle bombardment, with expression driven by constitutive promoters like CaMV 35S or maize-specific ubi promoters to ensure tissue-specific or whole-plant efficacy.

Major Traits and Varieties

Herbicide-tolerant maize

Herbicide-tolerant maize expresses transgenes that confer resistance to specific broad-spectrum herbicides, permitting post-emergence applications to control weeds while minimizing damage to the crop itself. This trait simplifies weed management by allowing farmers to use non-selective herbicides like glyphosate or glufosinate, which inhibit essential plant enzymes or metabolic pathways in susceptible weeds. The primary mechanism for glyphosate tolerance involves the CP4 EPSPS gene derived from species, which encodes an enzyme variant insensitive to glyphosate's inhibition of the shikimate pathway, essential for aromatic amino acid synthesis. For glufosinate tolerance, the pat or bar gene from soil bacteria like Streptomyces encodes phosphinothricin acetyltransferase, which acetylates and detoxifies the herbicide, preventing its interference with glutamine synthetase and subsequent ammonia accumulation. Commercial glyphosate-tolerant varieties, branded as Roundup Ready by Monsanto (now Bayer), include events like GA21 and NK603, with GA21 receiving U.S. regulatory approval in 1997 following petitions by Monsanto and DeKalb Genetics Corporation. NK603 maize was approved for cultivation in the U.S. in 2000 and for import into the EU, expressing the CP4 EPSPS protein to enable glyphosate use at rates up to 3.36 kg acid equivalent per hectare without yield penalty. Glufosinate-tolerant LibertyLink maize, developed by Bayer CropScience, features events such as T25, approved in the U.S. in 1998, which incorporates the pat gene for tolerance to glufosinate-ammonium applications up to 1,000 g active ingredient per hectare. Stacked traits combining herbicide tolerance with insect resistance, such as NK603 × T25, have also gained approvals, allowing flexibility in herbicide choice. Adoption of herbicide-tolerant maize has been widespread, particularly in the U.S., where it comprised over 90% of planted corn acreage by 2020, often in stacked configurations with Bt traits. Empirical data indicate that effective weed control via these traits boosted U.S. maize yields by approximately 3,700 kg per hectare in 2005, equivalent to about $255 per hectare in added value at contemporary prices, primarily through reduced weed competition. Studies attribute yield gains to simplified herbicide regimes replacing multiple narrower-spectrum applications, with pre- and post-emergence glyphosate use enabling no-till practices that preserve soil structure and moisture. However, prolonged reliance on glyphosate has contributed to the evolution of resistance in over 50 weed species globally, including key maize competitors like Amaranthus spp. and Conyza canadensis, necessitating integrated management to sustain efficacy. Regulatory assessments, including those by the EPA and EFSA, have confirmed no unintended adverse effects on maize composition or agronomic performance from these modifications, with tolerance limited to the targeted herbicide. In regions like South America and Africa, adoption has expanded for smallholder farmers, correlating with reduced labor for manual weeding and herbicide costs, though outcomes vary with local weed pressures and management practices. Overall, herbicide-tolerant maize has facilitated shifts toward conservation tillage, cutting fuel and erosion, but demands vigilant resistance monitoring to avoid diminished returns from over-reliance on single modes of action.

Insect-resistant Bt maize

Insect-resistant Bt maize varieties are genetically engineered to express one or more insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt), which target specific lepidopteran and coleopteran pests by disrupting their midgut epithelium upon ingestion, leading to larval paralysis and death. The primary Bt toxins used include Cry1Ab or Cry1F for lepidopteran pests such as the European corn borer (Ostrinia nubilalis), and Cry3Bb1, mCry3A, or Cry34/35Ab1 for coleopteran pests like the western corn rootworm (Diabrotica virgifera virgifera). These proteins are produced throughout the plant, providing season-long protection without requiring external insecticide applications. The first commercial Bt maize, expressing Cry1Ab for ECB resistance, was developed by Monsanto and approved for planting in the United States in 1996 under the trade name YieldGard. Subsequent varieties incorporated additional toxins, such as Cry3Bb1 introduced in 2003 for rootworm control, and pyramided stacks combining multiple Bt proteins to delay resistance evolution. In Europe, MON 810 (Cry1Ab) was approved in 1998, though adoption has been limited due to regulatory and market factors. Field studies demonstrate near-complete efficacy against ECB, with Bt maize reducing larval tunneling by up to 100% compared to non-Bt controls in Central European trials, resulting in yield increases of 10-15%. For western corn rootworm, initial efficacy exceeded 90% post-2003 introduction, but pooled field data show a decline to about 80% by 2016 due to resistance development in some U.S. Midwest populations. Pyramided traits maintain higher efficacy against resistant strains, with area-wide suppression of ECB populations observed following widespread adoption. Adoption of Bt maize reached over 80% of U.S. corn acres by the mid-2010s, driven by yield gains of 5-24% over non-Bt hybrids in surveys and experiments, alongside reductions in insecticide applications by up to 37% for targeted pests. Globally, Bt maize contributed to cumulative production increases equivalent to 72% from yield benefits and 28% from input savings through 2016. Resistance management strategies, mandated by the U.S. EPA since 1998, include non-Bt refuges (5-20% of acreage) to preserve susceptible alleles and high-dose/refuge pyramids to slow evolutionary adaptation. Despite these, field-evolved resistance to single-toxin traits has occurred in rootworm by 2009 and ECB in isolated cases, attributed to refuge non-compliance and continuous planting without rotation. Scientific reviews find no verified adverse effects on human health from Bt proteins in maize, as they are degraded in the digestive tract and lack toxicity to mammals. Environmentally, Bt maize shows minimal impact on non-target invertebrates compared to insecticide-sprayed conventional maize, with reduced overall pesticide use and no significant changes in soil microbial communities or biodiversity in meta-analyses. However, Bt protein persistence in soil and potential toxicity to aquatic detritivores warrant ongoing monitoring.

Drought- and stress-tolerant varieties

Genetically modified maize varieties tolerant to drought incorporate transgenes that enhance physiological responses to water deficit, primarily by stabilizing cellular proteins and maintaining metabolic functions under stress. The leading commercial example is event MON 87460, developed by Monsanto (now ), which expresses the cspB gene derived from Bacillus subtilis. This cold shock protein B protects proteins from denaturation during dehydration, enabling sustained growth and yield when irrigation or rainfall is limited. The trait was deregulated by the U.S. Department of Agriculture in 2011 and first marketed as DroughtGard hybrids in 2013, targeting U.S. Corn Belt regions prone to variable precipitation. Field evaluations of MON 87460 hybrids have demonstrated empirical yield benefits under managed drought conditions. In rainfed trials across multiple U.S. locations from 2009 to 2012, these varieties maintained grain yields 5 to 10 bushels per acre higher than non-transgenic comparators during severe water stress, equivalent to a 5-8% advantage, while showing no yield penalty in non-stress environments. Independent assessments, including those by the European Food Safety Authority in 2012, confirmed enhanced agronomic performance without unintended compositional changes beyond the intended trait. A 2024 study in sub-Saharan Africa reported MON 87460 hybrids yielding up to 24% more under high-to-severe drought compared to conventional hybrids under low-to-moderate stress, attributing gains to reduced susceptibility rather than maximal yield boosts. These outcomes stem from randomized, replicated plots simulating reproductive-stage drought, underscoring causal links between the transgene and resilience via protein homeostasis rather than generalized vigor. Beyond the United States, MON 87460 has been integrated into African breeding programs through the Water Efficient Maize for Africa (WEMA) initiative, a public-private partnership involving Monsanto, CIMMYT, and national seed companies. This project licenses the trait royalty-free for smallholder farmers, combining it with insect resistance for stacked protection in drought-prone regions. Varieties incorporating MON 87460 received regulatory approval for cultivation in South Africa in 2023 under the TELA (Tropicalization of Leading Agronomic traits for drought and Efficiency in Africa) extension of WEMA, enabling commercial release to mitigate yield losses from erratic rainfall. Adoption data indicate limited but growing uptake, with DroughtGard hybrids comprising under 5% of U.S. corn acreage by 2018, reflecting targeted use in water-variable agroecologies rather than widespread replacement of conventional breeding approaches. For broader abiotic stresses beyond drought, such as heat or salinity, commercial GM maize remains scarce, with most advancements confined to research-stage transgenics expressing genes like DREB or NAC transcription factors for multi-stress tolerance. These experimental lines have shown promise in greenhouse and plot trials for combined drought-heat resilience, but lack large-scale field validation or market approval as of 2025, prioritizing single-trait drought engineering for regulatory and economic feasibility. Empirical data from such studies emphasize that GM stress tolerance augments, rather than supplants, agronomic practices like hybrid selection and irrigation management.

Stacked and specialty traits

Stacked traits in genetically modified maize refer to varieties incorporating multiple transgenic events, typically combining insect resistance (such as Bt toxins targeting lepidopteran and coleopteran pests) with herbicide tolerance (e.g., to glyphosate or glufosinate), achieved through conventional breeding crosses of single-event lines or direct multi-gene transformation. This stacking broadens pest management efficacy and reduces reliance on single-mode interventions, with regulatory assessments confirming compositional equivalence to non-GM counterparts in most cases. For instance, the variety 12-5 × IE034 stacks cry1Ab for insect resistance and epsps for glyphosate tolerance, demonstrating stable inheritance and no unintended genetic disruptions via breeding. Another example is Roundup Ready YieldGard corn, derived from crossing herbicide-tolerant and Bt events, approved for commercial use since the early 2000s. Adoption of stacked GM maize has risen sharply due to enhanced agronomic performance; in the United States, stacked varieties (often combining multiple Bt and herbicide-tolerance traits) comprised 83% of corn acres by 2023, reflecting farmer preferences for integrated resistance profiles amid evolving pest pressures. Globally, stacked events dominate approvals, with over 90% of U.S. corn being genetically engineered overall, predominantly in multi-trait configurations that minimize cross-resistance risks through diversified Bt proteins. Specialty traits in GM maize focus on output modifications altering grain composition for nutritional, feed, or industrial applications, distinct from input traits like pest resistance. Examples include lysine-enriched kernels, where transgenic expression boosts free lysine accumulation, improving swine growth rates, feed conversion, and carcass yields by 5-10% in feeding trials without affecting human safety. Phytase-producing GM maize, engineered to secrete the enzyme in kernels, enhances phosphorus bioavailability in animal diets, reducing supplemental phosphate needs by up to 40% and manure phosphorus excretion, thereby mitigating environmental runoff. These traits undergo rigorous compositional analysis, showing no substantive equivalence deviations beyond the targeted modification, though adoption remains niche (under 5% of total GM maize) due to market segmentation and regulatory hurdles in feed chains. Industrial specialty lines, such as those optimized for starch profiles or enzyme production, support sectors like bioethanol but face limited commercialization outside major producers.

Commercialization and Market Dynamics

Approved and marketed products

Numerous genetically modified maize varieties featuring herbicide tolerance, insect resistance, or stacked traits have been approved for commercial marketing worldwide, with the United States hosting the largest market and highest adoption rates exceeding 90% of planted acreage as of 2024. These products are developed primarily by companies such as Monsanto (now Bayer), Syngenta, Dow AgroSciences (now Corteva), and Pioneer, and are regulated through safety assessments by agencies including the USDA, EPA, and FDA in the US. Key early commercial products include:
Event CodeProduct/TraitDeveloperFirst Approval (Country)Primary Markets
MON810YieldGard (Bt insect resistance against corn borer)Monsanto1996 (USA)US, Canada, Europe (limited cultivation), Argentina, Brazil
NK603Roundup Ready Corn 2 (glyphosate herbicide tolerance)Monsanto2000 (USA)US, Canada, Japan (import), EU
GA21Roundup Ready Corn (glufosinate herbicide tolerance)Syngenta1998 (USA)US, Canada, EU
Bt11Agrisure CB/LL (Bt insect resistance and glufosinate tolerance)Syngenta1996 (USA)US, Canada, South Africa
TC1507Herculex I (Bt insect resistance against corn borer and rootworm)Dow AgroSciences/Pioneer2001 (USA)US, Brazil, Canada
Stacked trait varieties, combining multiple resistances (e.g., MON89034 × TC1507 × NK603 for dual Bt and herbicide tolerance), dominate current markets, comprising over 50% of US GM maize plantings by 2024 due to enhanced agronomic performance. Specialized products include Enogen (SYN-E3272-5), engineered for high alpha-amylase expression to improve ethanol production efficiency, marketed by Syngenta since 2011 primarily in the US for industrial use. In emerging markets, drought-tolerant varieties like TELA hybrids (e.g., incorporating MON87460), developed through partnerships including Monsanto and the African Agricultural Technology Foundation, received commercial release approvals in Nigeria in January 2024 and Ethiopia in February 2025, targeting smallholder farmers in sub-Saharan Africa. China's recent approvals for GM maize cultivation, including events like MON87460 × MON87411 for insect and herbicide resistance, entered commercial stages in 2024, with varieties from developers like Origin Agritech projected for broader planting. Overall, over 300 GM maize events have regulatory approvals globally, though commercial marketing is concentrated in 20+ countries with permissive policies, emphasizing traits proven to sustain yields under pest and weed pressures. In 2023, genetically modified maize occupied approximately 69.3 million hectares globally, representing about 34% of the total worldwide maize planting area. This area increased by 4.68% from the previous year, driven primarily by expansions in major producing countries such as the United States and Brazil. Adoption rates vary significantly by region. In the United States, over 90% of maize acres were planted with herbicide-tolerant or stacked trait varieties in 2024. Brazil and similarly exhibit high penetration rates exceeding 85% for GM maize hybrids. In contrast, the European Union maintains negligible adoption due to regulatory restrictions, with commercial cultivation limited to trace amounts in a few member states like Spain and Portugal.
Country/RegionApproximate GM Maize Adoption Rate (%)YearSource
United States902024
Brazil>852023
Argentina>852023
~852023
<12023
Trends indicate sustained growth in the and select developing countries, with cumulative approvals for 209 distinct GM maize events across multiple nations as of 2024. Recent regulatory approvals in signal potential for rapid expansion there, projecting up to 581 million mu (about 38.7 million hectares) under GM maize if adoption mirrors patterns in other adopters. However, resistance from consumer groups and regulatory hurdles in regions like parts of and have slowed uptake, though pilot programs in countries such as the show annual increases of around 31% in GM maize adoption among smallholder farmers. Overall, global GM maize area has expanded from near zero in 1996 to its current scale, reflecting agronomic advantages despite ongoing debates over long-term impacts.

Economic scale and projections

In 2024, genetically modified maize occupied approximately 68.4 million hectares globally, accounting for a major share of the 210 million hectares dedicated to all GM crops. This hectarage reflects high rates in leading producers, where GM varieties comprised over 90% of maize plantings in the United States (covering more than 86 million acres) and similar proportions in and . In 2020, the most recent year with detailed farm-level data, GM maize spanned 60.77 million hectares, or 33% of total global maize area, with stacked herbicide-tolerant and insect-resistant traits driving the majority of cultivation. Economic benefits at the farm level have been driven by yield gains and input cost reductions, yielding $1.55 billion in net income globally from GM in 2020, with the contributing 62% of this figure. Cumulative farm income from GM maize technologies reached $20.2 billion from 1996 to 2020, primarily from insect-resistant varieties that boosted production by 47.9 million tonnes in 2020 alone through an average yield increase of 17.7% over the period. These gains, equivalent to $70.50 per in the for insect-resistant traits, underscore the technology's role in enhancing productivity without proportional increases in planted area. Projections forecast sustained growth in GM maize adoption, supported by expanded approvals for stacked traits and regulatory progress in emerging markets. The global GMO corn market, valued at $270.2 billion in 2024, is expected to expand to $408.4 billion by 2032, reflecting a 5.3% driven by demand for higher-yielding varieties amid population pressures. Continued integration of drought-tolerant and other stress-resistant traits could further amplify these trends, particularly in and , where hectarage is projected to rise with improved frameworks.

Agronomic and Economic Benefits

Yield enhancements and productivity gains

Genetically modified maize varieties engineered for insect resistance, such as Bt maize expressing Bacillus thuringiensis toxins, reduce damage from lepidopteran pests like the European corn borer and Asian corn borer, which can cause yield losses of 10-30% in susceptible conventional varieties. Empirical field trials and meta-analyses indicate that Bt maize typically delivers yield gains of 5-25% compared to non-Bt counterparts under comparable conditions, with higher benefits observed in regions with high pest pressure. For instance, a 2018 analysis of genetically engineered maize hybrids reported an average yield increase of 10.1%, equivalent to 0.7 metric tons per hectare. In Vietnam, adoption of GM maize varieties resulted in yield improvements of 30.4% over conventional equivalents, based on on-farm data from 2015-2018. Herbicide-tolerant maize, enabling the use of or for post-emergence , minimizes competition from weeds that can reduce yields by 20-50% if unmanaged. Studies in the Corn Belt have found that genetically modified maize adoption positively impacts yields, with econometric models attributing part of the observed increases to improved weed management practices. A of global GM crop impacts, including maize, estimated average yield enhancements of 22% attributable to GM technologies, driven by both insect resistance and herbicide tolerance traits. These gains are particularly pronounced in stacked traits combining Bt and herbicide tolerance, where synergistic effects from reduced pest and weed pressures compound productivity benefits. Drought- and stress-tolerant GM maize varieties, such as those incorporating the MON87460 trait, sustain yields under water-limited conditions by enhancing water use efficiency and root architecture. Field evaluations in water-stressed environments have shown yield protections of 5-15% relative to conventional , helping to stabilize output amid variable rainfall. Overall, while conventional breeding and agronomic improvements contribute to maize yield trends, GM traits have provided measurable incremental gains, with US corn yields rising from approximately 120 bushels per acre in 1996 to over 170 bushels per acre by 2020, partly due to widespread GM adoption exceeding 90% for key traits. Critics, such as the , argue that Bt maize contributes only about 4% to US yield increases since the mid-1990s, emphasizing the role of non-GM factors, though broader peer-reviewed syntheses support higher attributions under pest-prone scenarios.

Pesticide and input reductions

Insect-resistant Bt maize varieties have substantially decreased applications by expressing Cry proteins toxic to lepidopteran pests such as the . In the United States, adopters of insect-resistant maize used 0.013 kg/ha less on average from 1998 to 2011, representing an 11.2% decline relative to non-adopters. Cumulatively, Bt maize displaced 41 million kilograms of s between 1996 and 2011. Globally, from 1996 to 2020, insect-resistant maize traits reduced active ingredient use by 85.4 million kilograms, a 41.2% decrease, with a 53.1% reduction observed in 2020 alone compared to conventional varieties. Herbicide-tolerant maize initially contributed to modest reductions in herbicide quantities, with U.S. adopters applying 1.2% less (0.03 kg/ha) from 1998 to 2011 versus non-adopters, alongside a 9.8% lower environmental impact . However, herbicide use trended upward over time among adopters, exceeding non-adopters by 2011, attributable to glyphosate-resistant weeds necessitating alternative or additional applications. A meta-analysis of , encompassing maize, reported an overall 37% reduction in pesticide use, though herbicide-tolerant traits showed inconsistent quantity decreases. These reductions have lowered associated input costs, including fuel for spraying. Globally, insect-resistant saved 90.2 million liters of fuel from 1996 to 2020 due to fewer applications. In , where GM insect-resistant covers 91% of acreage, farmers reduced spray runs from five to two per crop, yielding cumulative fuel savings of 369 million liters between 2008 and 2020 and a 56% drop in use. Herbicide-tolerant varieties facilitate reduced , further cutting fuel and labor inputs, though empirical quantification varies by region and practice adoption.

Farmer profitability and cost savings

Adoption of genetically modified (GM) , particularly insect-resistant (IR) Bt varieties and herbicide-tolerant (HT) traits, has delivered net positive profitability for farmers worldwide through a combination of yield enhancements and production cost reductions. Globally, the use of GM IR generated $67.8 billion in additional farm income from 1996 to 2020, equivalent to an average increase of $30 per , with 72% of benefits from higher yields (averaging 17.7%) and 28% from cost savings, primarily reduced applications totaling 85.4 million kilograms cumulatively. HT contributed further through lower costs, including reduced and fuel use, yielding additional income of approximately $12.7 billion in major markets like the . These gains persist despite elevated seed premiums, as the return on investment averages $3.76 per invested globally, rising to $5.22 in developing . In the United States, where GM maize occupies over 80% of planted area, Bt traits provided $34.3 billion in cumulative income gains, with average per- benefits of $81.5 from 7% yield increases and savings of 38 million kilograms. HT and stacked traits added value via simplified weed management, saving 2,257 million liters of fuel and reducing environmental impacts from tillage. In , Brazilian farmers realized $7.86 billion from Bt maize (1996-2020), averaging $53.7 per from yield gains of 4.7-20.1% and fuel savings of 369 million liters, while Argentine producers benefited from HT stacked traits yielding up to $102 per in second-crop systems. European and African contexts highlight benefits for smaller operations. In Spain, Bt maize adoption increased farm income by €50-100 per hectare through 10-20% yield gains and pesticide cost reductions of €20-40 per hectare. South African smallholder farmers experienced up to 32% yield improvements and $93.6 per hectare net gains with Bt white maize, alongside 30-50% drops in pesticide use, amplifying profitability relative to larger commercial farms. In the Philippines, Bt maize raised incomes by 20-30%, driven by 20-34% higher yields.
Region/CountryTraitAvg. Income Gain (USD/ha)Key Cost Savings
Bt81.5Insecticide: 38M kg reduced (1996-2020)
Bt53.7Fuel: 369M liters saved
Bt93.6 (small farms higher)Pesticide use: 30-50% lower
ArgentinaHT Stacked102.4Tillage/fuel reductions
Bt~70 (equiv.)Pesticide: €20-40/ha
These figures derive from farm-level analyses accounting for self-selection and regional variations, confirming consistent net profitability across scales, though benefits are tempered in areas with emerging pest resistance requiring integrated .

Environmental Effects

Biodiversity and non-target organism impacts

A systematic review of 76 studies published between 1996 and 2020 found that the cultivation of Bt maize, which expresses insecticidal Cry proteins targeting lepidopteran pests like the European corn borer, results in small and predominantly neutral effects on the abundance and ecological function of non-target invertebrate communities in maize fields, including predators, parasitoids, and decomposers. This analysis, encompassing field trials across multiple continents, indicated no consistent negative shifts in species diversity or population densities of beneficial arthropods such as ladybirds, lacewings, and ground beetles, with effects often attributable to reduced insecticide applications rather than the Bt trait itself. A 2007 meta-analysis of 42 field experiments similarly reported higher abundances of non-target invertebrates in Bt maize fields compared to non-Bt fields treated with chemical insecticides, attributing this to the specificity of Bt toxins, which degrade rapidly in the environment and spare most non-lepidopteran species. Field studies on soil-dwelling non-target organisms, including earthworms, collembolans, and microbial communities, have demonstrated negligible long-term impacts from Bt maize residues. For instance, Cry protein accumulation in soil from Bt maize root exudates and plant debris occurs at low concentrations that do not disrupt microbial diversity or enzyme activities essential for nutrient cycling, as confirmed by multi-year monitoring in European and North American trials. populations and reproduction rates remain comparable between Bt and conventional maize plots, with any transient reductions linked to lower pesticide use in Bt systems rather than direct . Broader biodiversity assessments, including arthropod community structure in adjacent habitats, show no significant adverse effects from GM maize adoption. A three-year field study in China comparing transgenic Cry1Ab/2Aj maize to conventional varieties found insignificant differences in the diversity indices (Shannon-Wiener and Simpson) of non-target arthropods, encompassing over 100 species across orders like and . Meta-analyses further indicate that Bt maize indirectly supports by suppressing target pests, thereby reducing the need for broad-spectrum sprays that harm non-target species, leading to net increases in pollinator and natural enemy populations in some agroecosystems. While isolated studies report minor sublethal effects on specific non-target herbivores sensitive to Cry proteins, these are rare, context-dependent, and outweighed by overall ecological stability, with no evidence of cascading at landscape scales.

Soil health and sustainability outcomes

Herbicide-tolerant genetically modified maize varieties, such as those expressing CP4 EPSPS for resistance, have facilitated widespread adoption of no-till and reduced- practices, which preserve by minimizing mechanical disturbance. These practices reduce by up to 90% in some U.S. corn fields compared to conventional , enhancing long-term and water retention. From 1996 to 2020, the use of such GM maize contributed to an estimated avoidance of 955 million tons of globally through conservation . Bt maize, engineered for insect resistance via Cry proteins, generally shows no long-term detrimental effects on microbial communities, with meta-analyses indicating neutral impacts on bacterial diversity and activities essential for nutrient cycling. Short-term shifts in or microbial composition have been observed following residue incorporation, attributed to differences in quality rather than the Bt toxin itself, which degrades rapidly in . Studies over multiple seasons confirm that Bt maize residues do not significantly alter overall microbial or functions compared to non-GM counterparts. Sustainability outcomes include improved , with no-till GM maize systems sequestering an additional 0.3-0.5 tons of organic carbon per hectare annually in key producing regions. This has led to a net reduction in agriculture's , equivalent to removing 15.2 million cars from the road annually from 1996-2020 due to lower fuel use in operations. Reduced reliance on broad-spectrum insecticides with Bt maize further supports invertebrate populations, indirectly benefiting microbial habitats, though residues require monitoring for potential minor effects on specific fungal communities in high-use scenarios. Overall, empirical data from field trials indicate that GM maize promotes metrics over conventional systems when integrated with conservation practices.

Gene flow management and resistance mitigation

Gene flow from genetically modified (GM) maize to non-GM cultivars or wild relatives occurs primarily through pollen dispersal, which is wind-mediated and decreases exponentially with distance, typically limited to 1-3% at 50 meters and near zero beyond several kilometers under standard conditions. Management strategies emphasize spatial and temporal isolation, such as planting GM and non-GM fields at sufficient distances (e.g., 200-600 meters depending on regulations) or staggering planting dates to desynchronize pollen shed, thereby reducing adventitious presence below thresholds like 0.9% in the European Union. In Mexico, where teosinte (Zea mays ssp. parviglumis) coexists as a wild relative, experimental crosses demonstrate low gene flow rates of approximately 2.7% from maize to teosinte under controlled conditions, with transgene persistence limited by selection against unfit hybrids in natural populations. Atmospheric models predict and validate these patterns, enabling site-specific risk assessments for coexistence without evidence of widespread ecological disruption from introgression. To mitigate insect resistance in Bt maize, which expresses Bacillus thuringiensis (Bt) toxins targeting lepidopteran pests like the , the high-dose/refuge (HD/R) strategy is mandated by regulatory bodies such as the U.S. Environmental Protection Agency. This approach requires GM fields to produce Bt toxin levels sufficiently high (at least 25 times the for susceptible pests) to kill heterozygous resistant individuals, while adjacent or intermixed non-Bt refuges (typically 20% of acreage for corn borer-targeted traits) sustain susceptible pest populations for with rare survivors from Bt fields, thereby delaying resistance evolution. Field monitoring since Bt maize commercialization in 1996 has confirmed the strategy's efficacy, with no widespread resistance in the after over two decades, as rare resistant alleles are swamped by susceptible mates from refuges. Innovations like "refuge-in-the-bag" (pre-mixed seeds) enhance compliance but require vigilant monitoring, as isolated cases of resistance in other pests underscore the need for adherence. Herbicide resistance mitigation in glyphosate- or glufosinate-tolerant GM relies on integrated weed management (IWM), including herbicide rotation, multiple modes of action, and cultural practices like or cover crops to reduce selection pressure on any single trait. Stacked traits combining tolerance to multiple herbicides (e.g., glyphosate plus 2,4-D or ) in single hybrids provide short-term flexibility, enabling diversified weed control programs that have sustained efficacy in high-adoption regions, though over-reliance risks accelerating multi-resistant weeds without IWM. Empirical data from U.S. fields show that diversified herbicide use in GM systems has limited resistance incidence compared to reliance, emphasizing proactive stewardship over trait stacking alone. Overall, these evidence-based protocols, informed by models, have preserved GM durability without documented systemic failures attributable to unmanaged or resistance.

Health and Safety Evidence

Human health assessments and consumption data

Regulatory bodies including the U.S. Food and Drug Administration (FDA), the (EFSA), and the (WHO) have evaluated numerous genetically modified (GM) maize events for human consumption, applying principles of substantial equivalence and targeted compositional analysis to assess , allergenicity, and nutritional profiles. These assessments consistently determine that approved GM maize varieties are as safe as their conventional counterparts, with no identified hazards unique to genetic modification. For instance, EFSA's 2024 review of maize DP910521 found no toxicological concerns and equivalence in agronomic and compositional traits to non-GM maize. Similarly, the FDA's voluntary pre-market consultation process for GM crops, including maize, confirms compliance with safety standards equivalent to non-GM foods. Peer-reviewed systematic reviews and consensus reports reinforce these findings, reporting no substantiated evidence of adverse health effects from GM maize consumption. The U.S. National Academies of Sciences, , and Medicine's 2016 analysis of over 1,000 studies concluded that GM crops, including , present no greater risk to health than conventional varieties, based on evaluations of allergenicity, , and long-term exposure. A 2022 of animal and studies on GM food consumption identified no significant adverse events linked to GM maize, attributing the absence of reported risks to rigorous pre-market testing rather than alone. Epidemiological data from populations with high GM crop intake further support safety, showing no correlations between GM maize-derived food consumption and increased incidence of cancer, reproductive disorders, or other diseases over periods exceeding 25 years. In the United States, where GM maize adoption reached 92% of planted acreage by 2023, derived products form a substantial dietary component, including (used in ~60% of processed foods), , oil, and ethanol-derived sweeteners, contributing an estimated 193 pounds of GM ingredients per person annually as of early adoption data. Globally, human maize consumption averages 18.5 kg per capita per year, with GM varieties comprising the majority in major producers like the U.S., , and , yet WHO reports no verified negative health outcomes from such intake since commercialization in 1996. Time-series epidemiological analyses in high-adoption regions detect no disease patterns attributable to GM maize, underscoring the empirical safety record amid trillions of meals consumed.

Animal feeding trials and long-term studies

Numerous short-term animal feeding trials, typically 90 days in duration, have evaluated the safety of genetically modified (GM) maize varieties, including those expressing Bt toxins or herbicide tolerance traits, in species such as rats, mice, , and . These studies consistently report no significant differences in growth performance, organ weights, , clinical chemistry, or between animals fed GM maize and those fed isogenic non-GM controls. For instance, trials with chickens and fed GM maize event DP-915635-4 demonstrated nutritional equivalence and absence of adverse health effects on growth or organ function. Longer-term studies, extending beyond 90 days or across multiple generations, further support these findings. A 7-year feeding trial in cynomolgus macaques consuming expressing Cry1Ab/Cry2Aj and G10evo-EPSPS proteins showed no impacts on immune function, metabolic profiles, or reproductive outcomes in dams and offspring, as assessed via metagenomic and metabolomic analyses. Similarly, multi-generational studies and extended feeding experiments have found no evidence of , carcinogenicity, or reproductive harm attributable to consumption. A 2022 systematic review of 87 studies on GM food consumption, including , identified mostly non-significant differences in health parameters between GM-fed and control groups, though it noted isolated reports of adverse events like histopathological changes in 22 studies; however, these were attributed to low statistical power and variability in study designs rather than conclusive evidence of risk. Regulatory panels, such as the , have reviewed such data for specific GM events (e.g., MZHG0JG, DP910521) and concluded equivalence in safety to conventional , with no identified post-market monitoring needs for health. Some contested studies, like the 2012 Séralini rat trial alleging tumor development from NK603 GM , reported higher mortality and organ pathologies but faced criticism for inadequate sample sizes, lack of dose-response data, and reliance on historical controls, leading to initial retraction and limited acceptance in subsequent peer reviews. Overall, the preponderance of peer-reviewed evidence from controlled trials affirms the safety of GM in diets.

Regulatory toxicology reviews

Regulatory agencies worldwide, including the (EFSA), the U.S. (FDA), and , conduct toxicology reviews for genetically modified (GM) maize varieties as part of pre-market safety assessments. These reviews evaluate potential toxic effects through targeted testing of novel proteins (e.g., Cry proteins from in Bt maize), compositional equivalence to non-GM counterparts, and whole-food feeding studies in . Acute oral toxicity tests on purified proteins typically show no adverse effects at doses exceeding expected human exposure by orders of magnitude, due to the proteins' rapid degradation in mammalian digestion and lack of specific receptors in non-target organisms. Subchronic and chronic feeding trials, often 90-day rodent studies mandated by regulators like EFSA, compare GM maize diets to isogenic non-GM controls, assessing endpoints such as body weight, organ pathology, hematology, and . For instance, EFSA's GMO Panel reviewed maize MON 87419, expressing a modified Cry protein, and found no toxicologically significant differences in these parameters across tested groups, concluding equivalence in safety to conventional maize. Similar outcomes were reported for maize MON 95275 and DP51291, where molecular, agronomic, and toxicological data supported approvals without identified hazards. Allergenicity assessments, integrated into toxicology reviews, test for to known allergens and IgE reactivity, consistently yielding negative results for GM maize traits like those in Bt11 or NK603 varieties. FDA consultations for events such as YieldGard (MON810) confirmed no concerns based on submitted data, including and evaluations. While some critiques question the sufficiency of whole-food studies versus isolated protein tests, regulatory frameworks prioritize substantial equivalence and targeted , with over 100 GM crop approvals worldwide showing no verified toxic effects attributable to genetic modification.

Controversies and Scientific Debates

Alleged health risks and debunked studies

Alleged concerns regarding the health effects of genetically modified (GM) maize have primarily focused on potential , carcinogenicity, and allergenicity from traits such as tolerance (e.g., glyphosate-resistant NK603) and resistance (e.g., Bt proteins). These claims often stem from animal feeding studies or assays suggesting organ damage, reproductive issues, or immune responses, but comprehensive regulatory evaluations by bodies like the (EFSA) and the U.S. (FDA) have consistently found GM maize compositionally equivalent to conventional varieties, with no evidence of unique hazards to human health after toxicological testing. A widely cited but ultimately debunked study by Séralini et al. (2012) reported higher tumor incidence and mortality in Sprague-Dawley rats fed Roundup-tolerant NK603 maize over two years, attributing effects to the GM trait and associated glyphosate residues. The paper, published in Food and Chemical Toxicology, was retracted in November 2013 due to inconclusive results, inadequate statistical power from small sample sizes (10 rats per group), and ethical concerns over prolonging animal suffering from unchecked tumor growth. Independent reviews highlighted flaws including the use of a rat strain genetically prone to spontaneous mammary tumors (up to 80% in controls by age two), absence of dose-response relationships, and comparable tumor patterns in control groups when reanalyzed, rendering claims of causation unsubstantiated. The study was republished in 2014 in Environmental Sciences Europe without revisions to methodology or data, but experts maintained that it failed basic standards for long-term rodent carcinogenicity testing, such as those outlined by the (OECD). Other alleged risks, such as Bt Cry proteins causing gut inflammation or allergies in humans, have been tested in multiple feeding trials and dismissed due to lack of bioavailability (Bt toxins degrade in the digestive tract) and no observed adverse effects in livestock consuming billions of tons of Bt maize annually since 1996. A 2018 meta-analysis of 21 years of field and lab data on GM maize traits found no toxicological differences from non-GM counterparts, while regulatory renewals for events like MON 87427 (as of 2025) confirm no new hazards or exposure changes post-market. Claims from non-peer-reviewed or advocacy-linked sources, including in vitro cell studies suggesting Bt toxicity, have not replicated in vivo and are contradicted by epidemiological data showing no rise in health issues correlated with GM maize adoption. Overall, meta-analyses and long-term primate studies (e.g., seven-year macaque feeding trial) affirm safety, with no verified causal links to human disease.

Biodiversity and ecosystem concerns

Concerns regarding the and ecosystem impacts of genetically modified (GM) maize cultivation center on potential effects on non-target organisms, to wild or native relatives, and disruptions to soil microbial communities, though extensive field data indicate these risks are generally minimal and context-specific. Studies on Bt maize, engineered to produce Cry proteins toxic to target pests such as the (Ostrinia nubilalis), demonstrate small and predominantly neutral effects on non-target communities in fields, with meta-analyses of over 40 experiments showing higher abundances of beneficial arthropods like predators and parasitoids compared to insecticide-treated non-Bt maize. This outcome stems from reduced applications of broad-spectrum insecticides, which preserve pollinators and natural enemies, thereby supporting higher trophic levels in agroecosystems. Initial laboratory-based alarms about Bt pollen harming monarch butterflies (Danaus plexippus) via milkweed contamination have been refuted by field-scale assessments quantifying negligible exposure and no detectable population declines attributable to GM maize. Gene flow from GM maize to wild relatives poses a localized risk in centers of origin like Mexico, where transgenes have been detected in native landraces and teosinte (Zea mays ssp. parviglumis) at low frequencies (e.g., up to 1-2% in some surveys), potentially accelerating erosion of traditional through hybridization and selection pressures. Outside such regions, where maize lacks close wild progenitors, transgene persistence in feral populations is rare due to poor fitness of escaped GM volunteers and natural dynamics favoring over invasion. Management strategies, including buffer zones and temporal isolation, have proven effective in limiting cross-pollination rates to below 1% at distances over 100 meters in commercial settings. Evaluations of soil ecosystems reveal no persistent shifts in bacterial or fungal diversity linked to GM maize traits, with rhizosphere communities exhibiting comparable alpha-diversity and functional stability to those under conventional maize across multi-year trials. Herbicide-tolerant varieties may indirectly influence microbial guilds via altered weed management, but these effects mirror those from conventional tillage and do not indicate broad ecological disruption. Long-term monitoring since commercialization in 1996 supports the absence of systemic harm, with some evidence of net benefits from decreased contamination and enhanced retention through higher yields. Claims of widespread ecosystem degradation often originate from advocacy groups with documented anti-GM biases, contrasting with peer-reviewed syntheses emphasizing empirical null or positive outcomes.

Socioeconomic and policy criticisms

Critics contend that protections, particularly utility patents on genetically modified maize traits, confer excessive to a handful of firms, such as (formerly ) and , enabling them to dictate seed pricing and terms of use. These patents typically prohibit farmers from saving and replanting seeds, necessitating annual purchases that elevate costs—GM maize seeds can command premiums of 50-100% over conventional varieties—while fostering dependency on proprietary inputs like associated herbicides. This structure, opponents argue, entrenches corporate control over global seed supplies, with four companies holding over 60% of the U.S. corn seed market by the early , potentially stifling and independent breeding efforts. Non-adopting and organic farmers face socioeconomic risks from cross-pollination, which can contaminate fields and trigger lawsuits from seed patent holders, even in cases of unintentional exposure. Between 1997 and 2010, one major firm pursued 144 such actions against U.S. farmers, imposing financial burdens that disproportionately affect smaller operations unable to afford or buffer zones. In developing countries, where smallholders predominate, barriers—including upfront costs and limited credit access—may exacerbate income disparities, as wealthier producers capture yield benefits while poorer ones remain sidelined, with no conclusive evidence that GM maize resolves broader agrarian inequities. Policy frameworks promoting GM maize commercialization have drawn scrutiny for inadequate safeguards against overreliance, exemplified by the rapid proliferation of Bt rootworm-resistant varieties in the U.S. . A 2025 analysis of 12 years of field data across 10 states, published in Science, revealed that farmers' tendency to plant Bt maize beyond economically optimal levels—driven by perceived benefits—accelerated rootworm resistance, yielding net losses estimated at $2-3 billion annually in reduced efficacy and remedial inputs. Internationally, trade policies under agreements like the USMCA have been criticized for pressuring importing nations, such as , to accept GM maize despite domestic preferences for non-GM varieties in staple foods like tortillas, prioritizing exporter interests over local agricultural and preservation.

Regulation and Governance

Frameworks in major adopting countries

In the United States, the primary regulatory framework for genetically modified (GM) maize is the Coordinated Framework for Regulation of Biotechnology, established in 1986 and updated in 2017, which coordinates oversight among three agencies: the U.S. Department of Agriculture (USDA) for plant pest risks and agriculture, the Environmental Protection Agency (EPA) for pesticidal traits like Bt proteins in maize, and the Food and Drug Administration (FDA) for food and feed safety. This product-based approach evaluates GM maize varieties for novel hazards rather than the genetic modification method itself, requiring developers to submit data on molecular characterization, toxicity, allergenicity, and compositional equivalence to conventional maize; approvals, such as for MON 810 Bt maize in 1996, have enabled over 90% adoption of GM traits in U.S. maize acreage by 2024. Deregulation by USDA's Animal and Plant Health Inspection Service (APHIS) follows field trials and risk assessments confirming no increased plant pest risks, with no pre-market approval needed for contained uses. Brazil, the second-largest producer of GM maize with over 66 million hectares planted in 2023, regulates GM crops under the Biosafety Law (Law No. 11.105/2005), administered by the National Technical Commission on (CTNBio), an independent scientific body that conducts risk assessments focusing on human health, environmental impacts, and . Developers must submit dossiers including agronomic data, toxicity studies, and gene stability analyses; CTNBio approvals, such as for herbicide-tolerant maize in 2008, are valid nationwide without further state-level vetoes, though the National Council (CNBS) reviews for policy alignment. This framework emphasizes technical expertise over political considerations, facilitating rapid commercialization—GM maize now comprises about 85% of Brazil's harvested area—and includes mandatory labeling for products containing over 1% GM material since 2003. Argentina's framework, governed by Resolution 1,439/1991 and subsequent updates like Resolution 43/2015 for gene-edited crops without foreign DNA, relies on the National Advisory Commission on (CONABIA), a multidisciplinary body assessing environmental release and commercialization based on case-by-case risk evaluations of , resistance development, and ecological effects. For GM maize events like NK603 (approved 2001), applicants provide multi-year field data and molecular profiling; CONABIA's product-oriented process, informed by international standards, has supported GM occupying over 90% of Argentina's 6 million hectares by 2022, with no mandatory segregation for non-GM markets. The system distinguishes GMOs from conventional breeding outcomes, exempting the latter from oversight if no transgenes are present. In , GM maize regulation falls under Health Canada's Food Directorate for novel food safety and the Canadian Food Inspection Agency (CFIA) for environmental and feed assessments, using a voluntary notification process for low-risk traits but requiring pre-market authorizations for those posing potential allergenicity or risks, as with Bt maize approved in 1996. Assessments compare GM varieties to non-GM counterparts for nutritional equivalence and unintended effects, without distinguishing the modification technique; by 2024, GM traits cover about 80% of Canada's maize production, supported by streamlined rules for gene-edited crops lacking novel proteins since 2016 amendments. No mandatory labeling exists, as approvals deem products substantially equivalent. South Africa's GMO Act of 1997 establishes a precautionary framework via the Executive Council for GMO Use, advised by risk and committees, mandating environmental, health, and socio-economic impact assessments for GM maize releases, such as Bt varieties commercialized since 1998. Approvals require contained trials followed by general releases with monitoring; however, a 2024 ruling overturned authorization for a drought-tolerant GM event, citing inadequate application of the and procedural flaws, highlighting tensions between scientific evidence and judicial oversight in a where GM constitutes around 85% of plantings.

International approvals and trade barriers

Genetically modified maize varieties have received regulatory approvals for cultivation, , and use in and feed across numerous countries, primarily those employing science-based frameworks. As of 2024, over 30 countries have approved GM maize events, including the , , , , , and , where stacked traits for insect resistance and herbicide tolerance dominate commercial planting. In these jurisdictions, approvals follow evaluations by bodies such as the U.S. , Environment , and Brazil's National Technical Commission on Biosafety, confirming no increased risks compared to conventional based on compositional analyses, , and agronomic data. Global planting area for GM exceeded 60 million hectares in 2023, led by the U.S. (approximately 90% of its acreage), , and , reflecting broad acceptance where economic benefits like yield stability and are empirically demonstrated. In the , approvals for GM maize import and processing occur under Directive 2001/18/EC and Regulation (EC) No 1829/2003, but cultivation remains restricted. The has authorized over 50 GM maize events for food and feed since 2004, including renewals and new varieties like MON 87427 in 2025, following opinions finding equivalence to non-GM counterparts. However, no new cultivation approvals have been granted since MON810 (Bt maize) in 1998, with 19 member states opting out under Article 26(1) of Directive 2001/18/EC as of 2023, citing socioeconomic or environmental concerns unsubstantiated by risk assessments. Cultivation is limited to (over 100,000 hectares annually), , , Czechia, and , comprising less than 0.1% of EU maize area. Trade barriers have arisen from divergent regulatory philosophies, often challenged via international agreements. The 2003-2006 WTO dispute (DS291) saw the , , and prevail against the EU's de facto moratorium on GM approvals from 1998-2003, with the panel ruling that import bans on approved varieties like Bt maize lacked support, violating Sanitary and Phytosanitary Agreement obligations. More recently, under the USMCA, a 2024 dispute resolved in U.S. favor ruled 's 2023 decree banning GM maize for human consumption (e.g., tortillas) and glyphosate use unscientific, as Mexico failed to provide evidence of risks beyond those addressed in approvals elsewhere; Mexico repealed import restrictions in February 2025 while maintaining a domestic planting ban. These rulings underscore that barriers not grounded in empirical hazard data impede trade, with U.S. exports of GM maize to valued at over $5 billion annually pre-dispute. In Africa, approvals lag, with only , , and a few others permitting GM maize cultivation, though import tolerances exist in others, limiting intra-continental trade.

Recent policy shifts and bans

In , a 2020 presidential initiated a phaseout of genetically modified (GM) imports and use by 2024, citing health and environmental concerns, though subsequent revisions in 2023 focused the ban on GM for human consumption, particularly in tortillas, while allowing limited use in . This policy triggered a USMCA dispute filed by the in 2023, arguing the restrictions violated commitments, as GM constitutes over 90% of U.S. corn exports to . An panel ruled in December 2024 that Mexico's import prohibitions on GM for food and feed were unjustified, prompting Mexico to repeal the import ban in February 2025, ensuring continued access to U.S. supplies critical for its industry. Despite the import reversal, enshrined a constitutional on GM cultivation in March 2025, approved by the of , reinforcing prior restrictions on planting to protect native varieties and , even as domestic scientists advocate distinguishing gene-edited crops from traditional GMOs for faster approvals. This cultivation ban, effective nationwide, contrasts with the trade-mandated openness to imports, creating a that may expose ambiguities in enforcement for processed products. In the , regulatory approvals for GM maize imports and use in food and feed continued in 2025, with the authorizing varieties like DPØØ512Ø-9 on September 22, 2025, for a 10-year period, permitting processing but explicitly prohibiting cultivation within the bloc. Similar authorizations for three additional GM corn events followed, reflecting a procedural shift under updated that may lift a de facto moratorium on new GM approvals, though cultivation remains restricted or opted out by most member states under Directive 2015/412. South Africa's Supreme Court of Appeal overturned the approval of a drought-tolerant GM maize event in August 2025, invalidating the decision by regulatory authorities due to procedural flaws in , marking a setback for commercial release and prompting reviews of prior GMO authorizations. Meanwhile, emerging markets showed mixed trajectories: initiated public consultations in October 2025 for confined field trials of GM maize MON-ØØØ34, potentially advancing toward environmental release under its biosafety framework, while signaled a possible easing of its longstanding moratorium on GM food crops, including maize, amid U.S. trade negotiations.

Future Prospects

Pipeline developments and new traits

In the pipeline for genetically modified maize, developers prioritize stacked traits for enhanced pest resistance, alongside improvements in abiotic stress tolerance and nutrient efficiency to boost yield stability amid climate variability. Major agribusiness firms such as Bayer, Corteva Agriscience, and Syngenta lead these efforts, with recent regulatory approvals signaling commercialization of advanced insecticidal stacks. Syngenta's Durastak trait stack, approved by the U.S. EPA and launched in March 2025, incorporates three modes of action targeting corn rootworm, delivering 50% greater protection than prior single-trait options while enhancing standability and yield potential through reduced . Bayer's MON 95379 event, deregulated by the USDA on October 8, 2025, expresses to control lepidopteran pests including and corn earworm, building on existing Bt technologies for broader-spectrum efficacy in tropical and subtropical regions. Corteva plans near-term releases of reduced-stature maize hybrids engineered for resistance via modified pathways, with longer-horizon developments focusing on multi-disease stacks against pathogens like gray and northern corn leaf blight. Efforts to engineer nitrogen use efficiency (NUE) involve transgenic insertion of genes promoting architecture and nitrogen remobilization, as in constructs reducing nitrogen content by up to 50% while recycling foliar nitrogen to vegetative tissues, potentially cutting needs by 20-30% without yield penalties in field trials. pipelines feature transgenic lines overexpressing glycine betaine biosynthesis genes, which accumulated 2-3-fold higher osmoprotectants in stressed plants, improving photosynthetic rates and under water deficits compared to non-transgenic controls. These traits often integrate with herbicide tolerance for hybrids, addressing grower demands for simplified management, though full commercialization timelines extend 3-7 years post-deregulation pending stacked event stability and multi-country approvals.

Integration with advanced breeding tools

Advanced breeding tools, including CRISPR-Cas9 genome editing and genomic selection, have been integrated into maize breeding programs to complement transgenic genetic modification (GM) techniques, enabling more precise trait stacking and accelerated development of improved varieties. Transgenic GM introduces foreign genes, such as those conferring insect resistance from Bacillus thuringiensis (Bt), but often involves random insertion and lengthy backcrossing to minimize linkage drag; CRISPR-Cas9 addresses this by allowing targeted edits to endogenous maize genes, facilitating the refinement of GM lines or the introduction of complementary modifications without additional transgenes. For instance, multiplex CRISPR editing has been applied to generate maize lines with multiple simultaneous modifications, such as enhanced drought tolerance and yield stability, which can be stacked with existing GM traits like herbicide tolerance. This integration leverages the strengths of both approaches: GM provides novel traits from non-maize sources that editing alone cannot replicate, while precision tools reduce off-target effects and breeding time from years to generations. A 2023 study demonstrated /Cas9's capacity to produce over 1,000 edited maize variants targeting yield-related genes, which were then crossed into GM backgrounds to optimize complex polygenic traits like use . Similarly, the BREEDIT pipeline combines with high-throughput phenotyping to iteratively edit and select for multi-gene improvements in GM maize, achieving up to 20-30% gains in traits such as disease resistance when integrated with transgenic pest protection. Genomic selection models, informed by dense marker arrays, further enhance this by predicting performance of GM-edited hybrids, shortening cycles by identifying superior combinations early. Empirical outcomes include field-tested maize lines where CRISPR-edited reductions in content improved forage digestibility in Bt GM varieties, validated in trials showing 15% higher conversion rates without yield penalties. These advancements, pioneered in programs by institutions like since around 2016, have enabled the release of regulatory-exempt edited-GM hybrids in regions with flexible frameworks, though full commercialization often requires case-by-case evaluation due to stacked modifications. Challenges persist in delivery efficiency for polyploid maize, but variants of are emerging to enable transgene-free refinements, potentially expanding GM maize's adaptability to climate stressors.

References

  1. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/genetically-modified-maize
  2. https://www.nature.com/articles/s41598-018-21284-2
  3. https://www.fda.gov/food/agricultural-biotechnology/science-and-history-gmos-and-other-food-modification-processes
  4. https://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states
  5. https://www.ers.usda.gov/data-products/charts-of-note/chart-detail?chartId=110141
  6. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111629
  7. https://pmc.ncbi.nlm.nih.gov/articles/PMC7061863/
  8. https://www.nationalacademies.org/based-on-science/foods-made-with-gmos-do-not-pose-special-health-risks
  9. https://www.ars.usda.gov/news-events/news/research-news/2022/genetically-modified-corn-does-not-damage-non-target-organisms/
  10. https://doi.org/10.1007/s11032-021-01225-0
  11. https://pubmed.ncbi.nlm.nih.gov/37309443/
  12. https://doi.org/10.1007/BF00396083
  13. https://doi.org/10.1038/319791a0
  14. https://doi.org/10.1126/science.2832947
  15. https://doi.org/10.2307/3869124
  16. https://pmc.ncbi.nlm.nih.gov/articles/PMC10236110/
  17. https://ejbpc.springeropen.com/articles/10.1186/s41938-018-0051-2
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC9578716/
  19. https://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states/recent-trends-in-ge-adoption
  20. https://www.isaaa.org/resources/publications/briefs/17/default.html
  21. https://www.ers.usda.gov/sites/default/files/_laserfiche/publications/43731/13396_eib11_1_.pdf
  22. https://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=20476
  23. https://chilebio.cl/wp-content/uploads/2015/09/Quince-a%25C3%25B1os-de-cultivos-transg%25C3%25A9nicos-en-Argentina-15-Years-of-GM-Crops-in-Argentina-Versi%25C3%25B3n-en-ingl%25C3%25A9s.pdf
  24. https://www.researchgate.net/publication/359274849_GENETICALLY_MODIFIED_CORN_IN_BRAZIL_HISTORICAL_RESULTS_AND_PERSPECTIVES
  25. https://gm.agbioinvestor.com/downloads/9
  26. https://pgeconomics.co.uk/pdf/Globalimpactbiotechcropsfinalreportoctober2022.pdf
  27. https://www.isaaa.org/gmapprovaldatabase/
  28. https://pmc.ncbi.nlm.nih.gov/articles/PMC1062012/
  29. https://pubmed.ncbi.nlm.nih.gov/16667039/
  30. https://www.sciencedirect.com/science/article/pii/S0168945296045001
  31. https://www.nature.com/articles/nbt0696-745
  32. https://pubmed.ncbi.nlm.nih.gov/24243211/
  33. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.860971/full
  34. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.766702/full
  35. https://pmc.ncbi.nlm.nih.gov/articles/PMC8553389/
  36. https://clintonwhitehouse5.archives.gov/media/pdf/btmaize.pdf
  37. https://19january2021snapshot.epa.gov/sites/static/files/2015-08/documents/are_bt_crops_safe.pdf
  38. https://lgpress.clemson.edu/publication/managing-insect-pests-in-field-corn-using-transgenic-bt-technology/
  39. https://www.efsa.europa.eu/en/efsajournal/pub/2480
  40. https://www.isaaa.org/gmapprovaldatabase/gene/default.asp?GeneID=165
  41. https://pmc.ncbi.nlm.nih.gov/articles/PMC7680544/
  42. https://www.efsa.europa.eu/en/efsajournal/pub/2936
  43. https://pmc.ncbi.nlm.nih.gov/articles/PMC6356232/
  44. https://pmc.ncbi.nlm.nih.gov/articles/PMC9680014/
  45. https://www.isaaa.org/gmapprovaldatabase/gmtrait/default.asp?TraitID=1&GMTrait=Glufosinate%2520herbicide%2520tolerance
  46. https://onlinelibrary.wiley.com/doi/full/10.1002/ps.1008
  47. https://pmc.ncbi.nlm.nih.gov/articles/PMC9229215/
  48. https://hh-ra.org/wp-content/uploads/2017/03/Dill-Glyphosate-resistant-crops.pdf
  49. https://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=102
  50. https://www.fao.org/food/food-safety-quality/gm-foods-platform/browse-information-by/oecd-unique-identifier/oecd-unique-identifier-details/en/?ui=169503
  51. https://www.aphis.usda.gov/sites/default/files/97_09901p.pdf
  52. https://enveurope.springeropen.com/articles/10.1186/s12302-016-0070-0
  53. http://croplifeeurope.eu/wp-content/uploads/2021/01/nk603_key_facts_20150604.pdf
  54. https://pmc.ncbi.nlm.nih.gov/articles/PMC5598231/
  55. http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states/documentation
  56. http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states/recent-trends-in-ge-adoption
  57. https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2811&context=usdaarsfacpub
  58. https://agbioforum.org/wp-content/uploads/2021/02/AgBioForum-18-2-221.pdf
  59. https://pmc.ncbi.nlm.nih.gov/articles/PMC9291076/
  60. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.7730
  61. https://www.tandfonline.com/doi/full/10.1080/21645698.2025.2466915?af=R
  62. https://pmc.ncbi.nlm.nih.gov/articles/PMC10202092/
  63. https://www.cabidigitallibrary.org/doi/pdf/10.5555/20093074625
  64. https://pmc.ncbi.nlm.nih.gov/articles/PMC8231513/
  65. https://entomology.mgcafe.uky.edu/ef130
  66. https://pmc.ncbi.nlm.nih.gov/articles/PMC7915852/
  67. https://www.epa.gov/regulation-biotechnology-under-tsca-and-fifra/insect-resistance-management-bt-plant-incorporated
  68. https://www.nature.com/scitable/knowledge/library/use-and-impact-of-bt-maize-46975413/
  69. https://academic.oup.com/jee/article/116/2/275/6968981
  70. https://pps.agriculturejournals.cz/pdfs/pps/2012/10/04.pdf
  71. https://www.news.iastate.edu/news/too-much-good-thing-overuse-making-bt-corn-less-effective-against-rootworm
  72. https://www.pnas.org/doi/10.1073/pnas.1720692115
  73. https://www.ncbi.nlm.nih.gov/books/NBK424544/
  74. https://www.sciencedirect.com/science/article/pii/S221191241830049X
  75. https://www.pnas.org/doi/10.1073/pnas.2422337122
  76. https://pmc.ncbi.nlm.nih.gov/articles/PMC4413729/
  77. https://environmentalevidencejournal.biomedcentral.com/articles/10.1186/s13750-022-00272-0
  78. https://www.sciencedirect.com/science/article/pii/S0147651321009179
  79. https://www.canada.ca/en/health-canada/services/food-nutrition/genetically-modified-foods-other-novel-foods/approved-products/drought-tolerant-corn-87460.html
  80. https://acsess.onlinelibrary.wiley.com/doi/abs/10.2135/cropsci2013.07.0452
  81. https://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=98
  82. https://www.aatf-africa.org/breakthrough-study-shows-mon-87460-gene-enhances-maize-yield-under-drought-stress/
  83. https://www.sciencedirect.com/science/article/pii/S1687157X24000519
  84. https://www.cimmyt.org/projects/water-efficient-maize-for-africa-wema/
  85. https://www.aatf-africa.org/press-release-delivering-transgenic-drought-tolerant-and-insect-protected-maize-varieties-to-african-farmers/
  86. https://www.ers.usda.gov/amber-waves/2019/march/drought-tolerant-corn-in-the-united-states-research-commercialization-and-related-crop-production-practices
  87. https://pmc.ncbi.nlm.nih.gov/articles/PMC8617808/
  88. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.872566/full
  89. https://pmc.ncbi.nlm.nih.gov/articles/PMC8225737/
  90. https://www.isaaa.org/resources/publications/pocketk/42/default.asp
  91. https://pmc.ncbi.nlm.nih.gov/articles/PMC5595772/
  92. https://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-019-1956-y
  93. https://www.foodstandards.gov.au/consumer/gmfood/stackedgene
  94. https://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=21172
  95. https://www.isaaa.org/resources/publications/pocketk/41/default.asp
  96. https://www.tandfonline.com/doi/full/10.1080/21645698.2025.2472451?af=R
  97. https://www.isaaa.org/gmapprovaldatabase/crop/default.asp?CropID=6
  98. https://www.fda.gov/food/agricultural-biotechnology/gmo-crops-animal-food-and-beyond
  99. https://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=85
  100. https://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=86
  101. https://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=89
  102. https://www.isaaa.org/gmapprovaldatabase/eventslist/default.asp?CropID=6
  103. https://www.fas.usda.gov/data/nigeria-nigeria-becomes-second-african-country-approve-biotech-corn-commercial-planting
  104. https://www.fas.usda.gov/data/ethiopia-ethiopia-becomes-latest-african-country-approve-biotech-corn-commercial-production
  105. https://www.fas.usda.gov/data/china-new-genetically-modified-corn-and-soybean-variety-registration-list-published
  106. https://originagritech.com/origin-agritech-gmo-corn-hybrid-is-the-one-and-only-triple-stack-trait-corn-selected-for-national-demo-plot-being-grown-there-in-anticipation-of-2023-commercial-launch/
  107. https://www.sciencedirect.com/science/article/pii/S2095311924003332
  108. https://thehealthsciencesacademy.org/wp-content/uploads/2024/04/Global-GM-Crop-Area-Review_Feb2024.pdf
  109. https://pmc.ncbi.nlm.nih.gov/articles/PMC11944432/
  110. https://www.isaaa.org/blog/entry/default.asp?BlogDate=8/21/2024
  111. https://www.cell.com/molecular-plant/fulltext/S1674-2052%2824%2900078-9
  112. https://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=21375
  113. https://www.seedworld.com/latam/2025/07/21/adoption-record-transgenic-crops-reached-210-million-hectares-in-2024/
  114. https://www.nongmoproject.org/blog/the-gmo-high-risk-list-corn/
  115. https://www.gmiresearch.com/report/gmo-corn-market-analysis-industry-research/
  116. https://www.isaaa.org/blog/entry/default.asp?BlogDate=10/31/2024
  117. https://pmc.ncbi.nlm.nih.gov/articles/PMC7657581/
  118. https://pmc.ncbi.nlm.nih.gov/articles/PMC4218791/
  119. https://www.researchgate.net/publication/362118505_The_yield_and_price_effects_of_growing_genetically_modified_corn_evidence_from_the_US_corn_belt
  120. https://www.ucs.org/sites/default/files/2019-10/failure-to-yield.pdf
  121. https://geneticliteracyproject.org/2023/05/12/does-gmo-corn-increase-crop-yields-more-than-20-years-of-data-confirm-it-does-and-provides-substantial-health-and-safety-benefits/
  122. https://pmc.ncbi.nlm.nih.gov/articles/PMC5020710/
  123. https://enveurope.springeropen.com/articles/10.1186/2190-4715-24-24
  124. https://pmc.ncbi.nlm.nih.gov/articles/PMC9397136/
  125. https://pubmed.ncbi.nlm.nih.gov/17556584/
  126. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0002118
  127. https://pmc.ncbi.nlm.nih.gov/articles/PMC9572736/
  128. https://pmc.ncbi.nlm.nih.gov/articles/PMC5790416/
  129. https://link.springer.com/article/10.1007/s44279-025-00180-0
  130. https://pmc.ncbi.nlm.nih.gov/articles/PMC9559318/
  131. https://www.isaaa.org/resources/publications/pocketk/57/default.asp
  132. https://pmc.ncbi.nlm.nih.gov/articles/PMC12388455/
  133. https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.0020128
  134. https://journals.asm.org/doi/10.1128/AEM.71.11.6719-6729.2005
  135. https://geneticliteracyproject.org/2020/01/24/gmo-sustainability-advantage-glyphosate-sparks-no-till-farming-preserving-soil-carbon/
  136. https://www.fda.gov/food/agricultural-biotechnology/how-gmo-crops-impact-our-world
  137. https://pmc.ncbi.nlm.nih.gov/articles/PMC8965377/
  138. https://pmc.ncbi.nlm.nih.gov/articles/PMC7519140/
  139. https://enveurope.springeropen.com/articles/10.1186/s12302-021-00506-x
  140. https://www.isws.illinois.edu/docs/default-source/atmospheric-science/wang-pollen-application.pdf
  141. https://pmc.ncbi.nlm.nih.gov/articles/PMC3496990/
  142. https://experts.umn.edu/en/publications/success-of-the-high-doserefuge-resistance-management-strategy-aft
  143. https://repository.lsu.edu/entomology_pubs/762/
  144. https://bioone.org/journals/weed-science/volume-68/issue-2/wsc.2020.6/Modeling-the-Sustainability-and-Economics-of-Stacked-Herbicide-Tolerant-Traits/10.1017/wsc.2020.6.full
  145. https://pmc.ncbi.nlm.nih.gov/articles/PMC5250645/
  146. https://www.fda.gov/food/agricultural-biotechnology/how-gmos-are-regulated-united-states
  147. https://www.efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2024.8887
  148. https://www.who.int/news-room/questions-and-answers/item/food-genetically-modified
  149. https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2024.8887
  150. https://www.nationalacademies.org/news/2016/05/genetically-engineered-crops-experiences-and-prospects-new-report
  151. https://enveurope.springeropen.com/articles/10.1186/s12302-021-00578-9
  152. https://www.ncbi.nlm.nih.gov/books/NBK424534/
  153. http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states
  154. https://www.ewg.org/news-insights/news/americans-eat-their-weight-genetically-engineered-food
  155. https://link.springer.com/article/10.1007/s12571-022-01288-7
  156. https://www.who.int/news/item/23-06-2005-current-gm-foods-can-bring-benefits-but-safety-assessments-must-continue
  157. https://pmc.ncbi.nlm.nih.gov/articles/PMC10417801/
  158. https://jasbsci.biomedcentral.com/articles/10.1186/2049-1891-4-37
  159. https://pmc.ncbi.nlm.nih.gov/articles/PMC4015968/
  160. https://www.sciencedirect.com/science/article/pii/S0278691524002825
  161. https://www.sciencedirect.com/science/article/pii/S0278691525001875
  162. https://pubs.acs.org/doi/10.1021/acs.jafc.5c06423
  163. https://pmc.ncbi.nlm.nih.gov/articles/PMC7009398/
  164. https://enveurope.springeropen.com/articles/10.1186/s12302-020-0296-8
  165. https://www.tandfonline.com/doi/full/10.3109/10408444.2013.842956
  166. https://foodsystems.org/wp-content/uploads/2021/01/cry1ab_en_ffs.pdf
  167. https://pmc.ncbi.nlm.nih.gov/articles/PMC9853084/
  168. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2024.8886
  169. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2024.9059
  170. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2021.6347
  171. https://pmc.ncbi.nlm.nih.gov/articles/PMC11702926/
  172. https://www.sciencedirect.com/science/article/abs/pii/S0160412011000055
  173. https://www.efsa.europa.eu/en/efsajournal/pub/9380
  174. https://www.sciencedirect.com/science/article/pii/S0278691512005637
  175. https://www.nature.com/articles/nature.2013.14268
  176. https://pmc.ncbi.nlm.nih.gov/articles/PMC4524344/
  177. https://enveurope.springeropen.com/articles/10.1186/s12302-015-0048-3
  178. https://pmc.ncbi.nlm.nih.gov/articles/PMC3001031/
  179. https://pmc.ncbi.nlm.nih.gov/articles/PMC7211868/
  180. https://www.pnas.org/doi/10.1073/pnas.1817664116
  181. https://www.nature.com/articles/s41598-020-72805-x
  182. https://pmc.ncbi.nlm.nih.gov/articles/PMC11434164/
  183. https://www.sciencedirect.com/science/article/abs/pii/S0929139319305785
  184. https://www.ars.usda.gov/ARSUserFiles/50701000/cswq-0012-158141.pdf
  185. https://pubmed.ncbi.nlm.nih.gov/17522828/
  186. https://usrtk.org/wp-content/uploads/2024/11/DOSSIER-MAIZ-2024-ENGfinal-5.pdf
  187. https://www.ers.usda.gov/amber-waves/2023/august/expanded-intellectual-property-protections-for-crop-seeds-increase-innovation-and-market-power-for-companies
  188. https://scholarship.law.tamu.edu/cgi/viewcontent.cgi?article=1224&context=lawreview
  189. https://www.farmaid.org/issues/gmos/gmos-top-5-concerns-for-family-farmers/
  190. https://environmentalevidencejournal.biomedcentral.com/articles/10.1186/2047-2382-3-24
  191. https://food.ec.europa.eu/system/files/2016-10/gmo_rep-stud_gmo-survey_2010_aut_impacts.pdf
  192. https://ag.purdue.edu/news/2025/02/midwestern-field-trials-suggest-overuse-of-rootworm-resistant-corn-reduces-farmers-profits.html
  193. https://usrtk.org/gmo/trade-panel-us-can-compel-mexico-to-accept-gm-corn/
  194. https://www.wilsoncenter.org/article/gmo-corn-case-and-north-american-integration-sin-maiz-no-hay-pais-meets-king-corn
  195. https://www.epa.gov/regulation-biotechnology-under-tsca-and-fifra/genetically-modified-organisms
  196. https://www.ncbi.nlm.nih.gov/books/NBK424533/
  197. https://apps.fas.usda.gov/newgainapi/api/Report/DownloadReportByFileName?fileName=Agricultural%20Biotechnology%20Annual_Brasilia_Brazil_BR2023-0027.pdf
  198. https://pmc.ncbi.nlm.nih.gov/articles/PMC12111335/
  199. https://www.sciencedirect.com/science/article/pii/S0963996920300788
  200. https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.834589/full
  201. https://apps.fas.usda.gov/newgainapi/api/Report/DownloadReportByFileName?fileName=Agricultural%20Biotechnology%20Annual_Buenos%20Aires_Argentina_AR2022-0023.pdf
  202. https://pubmed.ncbi.nlm.nih.gov/26552666/
  203. https://www.canada.ca/en/health-canada/services/food-nutrition/genetically-modified-foods-other-novel-foods.html
  204. https://pmc.ncbi.nlm.nih.gov/articles/PMC5033218/
  205. https://cban.ca/gmos/issues/regulation/
  206. https://www.grainsa.co.za/the-regulatory-management-of-gmos-in-south-africa
  207. https://www.theeastafrican.co.ke/tea/sustainability/climate/why-south-africa-s-apex-court-reversed-gmo-approval-4806818
  208. https://geneticliteracyproject.org/2024/11/13/citing-the-precautionary-principle-south-african-high-court-rescinds-approval-of-drought-tolerant-gmo-corn/
  209. https://www.asil.org/insights/volume/4/issue/5/regulation-genetically-modified-foods
  210. https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2025.9380
  211. https://biosafety-info.net/articles/policy-and-regulation/majority-of-eu-member-states-opt-out-of-gm-crop-cultivation-2/
  212. https://royalsociety.org/news-resources/projects/gm-plants/what-gm-crops-are-currently-being-grown-and-where/
  213. https://www.theguardian.com/science/2006/feb/08/gm.wto
  214. https://ustr.gov/about-us/policy-offices/press-office/press-releases/2024/december/united-states-prevails-usmca-dispute-biotech-corn
  215. https://www.reuters.com/markets/commodities/after-trade-dispute-mexico-officially-bans-planting-gm-corn-2025-02-26/
  216. https://www.congress.gov/crs-product/R48083
  217. https://pmc.ncbi.nlm.nih.gov/articles/PMC11042066/
  218. https://cban.ca/gmos/issues/trade/canada-and-us-challenge-mexicos-ban-on-gm-corn/
  219. https://grains.org/mexico-gm-corn-ban-dispute-ends-in-win-for-u-s-corn-exporters/
  220. https://www.ofimagazine.com/news/mexico-officially-repeals-gm-corn-import-ban
  221. https://www.world-grain.com/articles/21021-mexico-officially-repeals-biotech-imports-corn-ban
  222. https://www.seedworld.com/latam/2025/03/24/mexico-approves-constitutional-ban-on-planting-genetically-modified-corn/
  223. https://geneticliteracyproject.org/2025/10/23/mexican-scientists-call-for-quick-approvals-of-gene-edited-crops-even-as-restrictions-persist-on-gmo-agriculture/
  224. https://www.bdlaw.com/publications/mexico-bans-the-cultivation-of-genetically-modified-corn-opening-door-for-other-restrictions-in-the-future/
  225. https://millingmea.com/eu-authorises-gm-maize-dp51291-for-food-and-feed-use/
  226. https://www.global-agriculture.com/global-agriculture/eu-approves-three-new-genetically-modified-corn-varieties-for-food-and-feed-global-impact-likely/
  227. https://www.politico.eu/article/gm-laws-to-pave-the-way-for-lifting-of-eu-approvals-ban/
  228. https://www.tandfonline.com/doi/full/10.1080/00139157.2025.2518738
  229. https://capitalethiopia.com/2025/10/26/environment-authority-initiates-public-hearing-for-environmental-release-of-gm-maize-mon-89/
  230. https://m.economictimes.com/news/economy/agriculture/us-trade-talks-may-be-cracking-indias-opposition-to-gm-crops/articleshow/124541629.cms
  231. https://www.dtnpf.com/agriculture/web/ag/crops/article/2025/10/01/companies-reveal-seeds-traits-coming
  232. https://www.seedworld.com/us/2025/10/08/a-new-corn-trait-wins-usda-deregulation/
  233. https://www.syngenta-us.com/newsroom/news_release_detail?id=229376
  234. https://www.dtnpf.com/agriculture/web/ag/crops/article/2024/10/24/seed-trait-companies-reveal-coming
  235. https://www.sciencedirect.com/science/article/pii/S2667064X25000429
  236. https://academic.oup.com/plcell/article/37/7/koaf139/8205499
  237. https://www.agriculturejournal.org/volume12number3/advancements-in-crop-yield-improvement-through-genetic-engineering/
  238. https://pmc.ncbi.nlm.nih.gov/articles/PMC11477287/
  239. https://pmc.ncbi.nlm.nih.gov/articles/PMC10236071/
  240. https://pmc.ncbi.nlm.nih.gov/articles/PMC9990078/
  241. https://www.sciencedirect.com/science/article/pii/S2468014124001675
  242. https://www.biochemjournal.com/archives/2025/vol9issue10S/PartM/S-9-10-99-905.pdf
  243. https://pmc.ncbi.nlm.nih.gov/articles/PMC12052613/
  244. https://www.news.iastate.edu/news/isu-researchers-part-nationwide-project-make-sweet-corn-even-better
  245. https://link.springer.com/chapter/10.1007/978-3-031-46150-7_11
  246. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1478398/full
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