An analytical approach to the implementation of genetically modified crops

Public scepticism towards genetically modified (GM) crops is increasing. To address this, the risks and benefits of GM crops must be examined across scientific disciplines, and be discussed with the authorities, the agricultural industry and the consumers. In a feasibility study we have systematically analysed the challenges of the development and marketing of GM crops in Europe. A life-cycle inventory was used together with established technology foresight techniques in an interdisciplinary and empirical framework. The approach taken in this study established a dialogue between stakeholders and provided a framework for discussions about the future direction of GM crops.     

Renegotiating GM crop regulation. Targeted gene-modification technology raises new issues for the oversight of genetically modified crops

Targeted genetic modification, which enables scientists to genetically engineer plants more efficiently and precisely, challenges current process-based regulatory frameworks for genetically modified crops.In 2010, more than 85% of the corn acreage and more than 90% of the soybean acreage in the USA was planted with genetically modified (GM) crops (USDA, 2010). Most of those crops contained transgenes from other species, such as bacteria, that confer resistance to herbicides or tolerance to insect pests, and that were introduced into plant cells using Agrobacterium or other delivery methods. The resulting ‘transformed'' cells were regenerated into GM plants that were tested for the appropriate expression of the transgenes, as well as for whether the crop posed an unacceptable environmental or health risk, before being approved for commercial use. The scientific advances that enabled the generation of these GM plants took place in the early 1980s and have changed agriculture irrevocably, as evidenced by the widespread adoption of GM technology. They have also triggered intense debates about the potential risks of GM crops for human health and the environment and new forms of regulation that are needed to mitigate this. There is also continued public resistance to GM crops, particularly in Europe.Plant genetic engineering is at a technological inflection pointPlant genetic engineering is at a technological inflection point. New technologies enable more precise and subtler modification of plant genomes (Weinthal et al, 2010) than the comparably crude methods that were used to create the current stock of GM crops (Fig 1A). These methods allow scientists to insert foreign DNA into the plant genome at precise locations, remove unwanted DNA sequences or introduce subtle modifications, such as single-base substitutions that alter the activity of individual genes. They also raise serious questions about the regulation of GM crops: how do these methods differ from existing techniques and how will the resulting products be regulated? Owing to the specificity of these methods, will resulting products fall outside existing definitions of GM crops and, as a result, be regulated similarly to conventional crops? How will the definition and regulation of GM crops be renegotiated and delineated in light of these new methods?Open in a separate windowFigure 1Comparing traditional transgenesis, targeted transgenesis, targeted mutagenesis and gene replacement. (A) In traditional transgenesis, genes introduced into plant cells integrate at random chromosomal positions. This is illustrated here for a bacterial gene that confers herbicide resistance (Herb^r). The plant encodes a gene for the same enzyme, however due to DNA-sequence differences between the bacterial and plant forms of the gene, the plant gene does not confer herbicide resistance (Herb^s). (B) The bacterial herbicide-resistance gene can be targeted to a specific chromosomal location through the use of engineered nucleases. The nucleases recognize a specific DNA sequence and create a chromosome break. The bacterial gene is flanked by sequences homologous to the target site and recombines with the plant chromosome at the break site, resulting in a targeted insertion. (C) Engineered nucleases can be used to create targeted gene knockouts. In this illustration, a second nuclease recognizes the coding sequence of the Herb^s gene. Cleavage and repair in the absence of a homologous template creates a mutation (orange). (D) A homologous DNA donor can be used to repair targeted breaks in the Herb^s gene. This allows sequence changes to be introduced into the native plant gene that confer herbicide resistance. Only a single base change is needed in some instances.Of the new wave of targeted genetic modification (TagMo) techniques, one of the most thoroughly developed is TagMo, which uses engineered zinc-finger nucleases or meganucleases to create DNA double-stranded breaks at specific genomic locations (Townsend et al, 2009; Shukla et al, 2009; Gao et al, 2010). This activates DNA repair mechanisms, which genetic engineers can use to alter the target gene. If, for instance, a DNA fragment is provided that has sequence similarity with the site at which the chromosome is broken, the repair mechanism will use this fragment as a template for repair through homologous recombination (Fig 1B). In this way, any DNA sequence, for instance a bacterial gene that confers herbicide resistance, can be inserted at the site of the chromosome break. TagMos can also be used without a repair template to make single-nucleotide changes. In this case, the broken chromosomes are rejoined imprecisely, creating small insertions or deletions at the break site (Fig 1C) that can alter or knock out gene function.TagMo technology would, therefore, challenge regulatory policies both in the USA and, even more so, in the [EU]…The greatest potential of TagMo technology is in its ability to modify native plant genes in directed and targeted ways. For example, the most widely used herbicide-resistance gene in GM crops comes from bacteria. Plants encode the same enzyme, but it does not confer herbicide resistance because the DNA sequence is different. Yet, resistant forms of the plant gene have been identified that differ from native genes by only a few nucleotides. TagMo could therefore be used to transfer these genes from a related species into a crop to replace the existing genes (Fig 1D) or to exchange specific nucleotides until the desired effect is achieved. In either case, the genetic modification would not necessarily involve transfer of DNA from another species. TagMo technology would, therefore, challenge regulatory policies both in the USA and, even more so, in the European Union (EU). TagMo enables more sophisticated modifications of plant genomes that, in some cases, could be achieved by classical breeding or mutagenesis, which are not formally regulated. On the other hand, TagMo might also be used to introduce foreign genes without using traditional recombinant DNA techniques. As a result, TagMo might fall outside of existing US and EU regulatory definitions and scrutiny.In the USA, federal policies to regulate GM crops could provide a framework in which to consider the way TagMo-derived crops might be regulated (Fig 2; Kuzma & Meghani, 2009; Kuzma et al, 2009; Thompson, 2007; McHughen & Smyth, 2008). In 1986, the Office of Science and Technology Policy established the Coordinated Framework for the Regulation of Biotechnology (CFRB) to oversee the environmental release of GM crops and their products (Office of Science and Technology Policy, 1986). The CFRB involves many federal agencies and is still in operation today (Kuzma et al, 2009). It was predicated on the views that regulation should be based on science and that the risks posed by GM crops were the “same in kind” as those of non-GM products; therefore no new laws were deemed to be required (National Research Council, 2000).Open in a separate windowFigure 2Brief history of the regulation of genetic engineering (Kuzma et al, 2009). EPA, Environmental Protection Agency; FIFRA, Federal Insecticide, Fungicide and Rodenticide Act; FDA, Food and Drug Administration; FPPA, Farmland Protection Policy Act; GMO, genetically modified organism; TOSCA, Toxic Substances Control Act; USDA, United States Department of Agriculture.Various old and existing statutes were interpreted somewhat loosely in order to oversee the regulation of GM plants. Depending on the nature of the product, one or several federal agencies might be responsible. GM plants can be regulated by the US Department of Agriculture (USDA) under the Federal Plant Pest Act as ‘plant pests'' if there is a perceived threat of them becoming ‘pests'' (similarly to weeds). Alternatively, if they are pest-resistant, they can be interpreted as ‘plant pesticides'' by the US Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act. Each statute requires some kind of pre-market or pre-release biosafety review—evaluation of potential impacts on other organisms in the environment, gene flow between the GM plant and wild relatives, and potential adverse effects on ecosystems. By contrast, the US Food and Drug Administration (FDA) treats GM food crops as equivalent to conventional food products; as such, no special regulations were promulgated under the Federal Food Drug and Cosmetic Act for GM foods. The agency established a pre-market consultation process for GM and other novel foods that is entirely voluntary.…TagMo-derived crops come in several categories relevant to regulation…Finally, and important for our discussion, the US oversight system was built mostly around the idea that GM plants should be regulated on the basis of characteristics of the end-product and not on the process that is used to create them. In reality, however, the process used to create crops is significant, which is highlighted by the fact that the USDA uses a process-based regulatory trigger (McHughen & Smyth, 2008). Instead of being inconsequential, it is important for oversight whether a plant is considered to be a result of GM.How will crops created by TagMo fit into this regulatory framework? If only subtle changes were made to individual genes, the argument could be made that the products are analogous to mutated conventional crops, which are neither regulated nor subject to pre-market or pre-release biosafety assessments (Breyer et al, 2009). However, single mutations are not without risks; for example, they can lead to an increase in expressed plant toxins (National Research Council, 1989, 2000, 2002, 2004; Magana-Gomez & de la Barca 2009). Conversely, if new or foreign genes are introduced through TagMo methods, the resulting plants might not differ substantially from existing GM crops. Thus, TagMo-derived crops come in several categories relevant to regulation: TagMo-derived crops with inserted foreign DNA from sexually compatible or incompatible species; TagMo-derived crops with no DNA inserted, for instance those in which parts of the chromosome have been deleted or genes inactivated; and TagMo-derived crops that either replace a gene with a modified version or change its nucleotide sequence (Fig 1).TagMo-derived crops with foreign genetic material inserted are most similar to traditional GM crops, according to the USDA rule on “Importation, Interstate Movement, and Release Into the Environment of Certain Genetically Engineered Organisms”, which defines genetic engineering as “the genetic modification of organisms by recombinant DNA (rDNA) techniques” (USDA, 1997). In contrast to conventional transgenesis, TagMo enables scientists to predefine the sites into which foreign genes are inserted. If the site of foreign DNA insertion has been previously characterized and shown to have no negative consequences for the plant or its products, then perhaps regulatory requirements to characterize the insertion site and its effects on the plant could be streamlined.TagMo might be used to introduce foreign DNA from sexually compatible or incompatible species into a host organism, either by insertion or replacement. For example, foreign DNA from one species of Brassica—mustard family—can be introduced into another species of Brassica. Alternatively, TagMo might be used to introduce foreign DNA from any organism into the host, such as from bacteria or animals into plants. Arguments have been put forth advocating less stringent regulation of GM crops with cisgenic DNA sequences that come from sexually compatible species (Schouten et al, 2006). Russell and Sparrow (2008) critically evaluate these arguments and conclude that cisgenic GM crops may still have novel traits in novel settings and thus give rise to novel hazards. Furthermore, if cisgenics are not regulated, it might trigger a public backlash, which could be more costly in the long run (Russell & Sparrow, 2008). TagMo-derived crops with genetic sequences from sexually compatible species should therefore still be considered for regulation. Additional clarity and consistency is needed with respect to how cisgenics are defined in US regulatory policy, regardless of whether they are generated by established methods or by TagMo. The USDA regulatory definition of a GM crops is vague, and the EPA has a broad categorical exemption in its rules for GM crops with sequences from sexually compatible species (EPA, 2001).Public failures will probably ensue if TagMo crops slip into the market under the radar without adequate oversightThe deletion of DNA sequences by TagMo to knock out a target gene is potentially of great agronomic value, as it could remove undesirable traits. For instance, it could eliminate anti-nutrients such as trypsin inhibitors in soybean that prevent the use of soy proteins by animals, or compounds that limit the value of a crop as an industrial material, such as ricin, which contaminates castor oil. Many mutagenesis methods yield similar products as TagMos. However, most conventional mutagenesis methods, including DNA alkylating agents or radioactivity, provide no precision in terms of the DNA sequences modified, and probably cause considerable collateral damage to the genome. It could be argued that TagMo is less likely to cause unpredicted genomic changes; however, additional research is required to better understand off-target effects—that is, unintended modification of other sites—by various TagMo platforms.We propose that the discussion about how to regulate TagMo crops should be open, use public engagement and respect several criteria of oversightGenerating targeted gene knockouts (Fig 1C) does not directly involve transfer of foreign DNA, and such plants might seem to warrant an unregulated status. However, most TagMos use reagents such as engineered nucleases, which are created by rDNA methods. The resulting product might therefore be classified as a GM crop under the existing USDA definition for genetic engineering (USDA, 1997) since most TagMos are created by introducing a target-specific nuclease gene into plant cells. It is also possible to deliver rDNA-derived nucleases to cells as RNA or protein, and so foreign DNA would not need to be introduced into plants to achieve the desired mutagenic outcome. In such cases, the rDNA molecule itself never encounters a plant cell. More direction is required from regulatory agencies to stipulate the way in which rDNA can be used in the process of generating crops before the regulated status is triggered.TagMo-derived crops that introduce alien transgenes or knock out native genes are similar to traditional GM crops or conventionally mutagenized plants, respectively, but TagMo crops that alter the DNA sequence of the target gene (Fig 1D) are more difficult to classify. For example, a GM plant could have a single nucleotide change that distinguishes it from its parent and that confers a new trait such as herbicide resistance. If such a subtle genetic alteration were attained by traditional mutagenesis or by screening for natural variation, the resulting plants would not be regulated. As discussed above, if rDNA techniques are used to create the single nucleotide TagMo, one could argue that it should be regulated. Regulation would then focus on the process rather than the product. If single nucleotide changes were exempt, would there be a threshold in the number of bases that can be modified before concerns are raised or regulatory scrutiny is triggered? Or would there be a difference in regulation if the gene replacement involves a sexually compatible or an incompatible species?Most of this discussion has focused on the use of engineered nucleases such as meganucleases or zinc-finger nucleases to create TagMos. Oligonucleotide-mediated mutagenesis (OMM), however, is also used to modify plant genes (Breyer et al, 2009). OMM uses chemically synthesized oligonucleotides that are homologous to the target gene, except for the nucleotides to be changed. Breyer et al (2009) argue that OMM “should not be considered as using recombinant nucleic acid molecules” and that “OMM should be considered as a form of mutagenesis, a technique which is excluded from the scope of the EU regulation.” However, they admit that the resulting crops could be considered as GM organisms, according to EU regulatory definitions for biotechnology. They report that in the USA, OMM plants have been declared non-GM by the USDA, but it is unclear whether the non-GM distinction in the USA has regulatory implications. OMM is already being used to develop crops with herbicide tolerance, and so regulatory guidelines need to be clarified before market release.In turning to address how TagMo-related oversight should proceed, two questions are central: how are decisions made and who is involved in making them? The analysis above illustrates that many fundamental decisions need to be made concerning the way in which TagMo-derived products will be regulated and, more broadly, what constitutes a GM organism for regulatory purposes. These decisions are inherently values-based in that views on how to regulate TagMo products differ on the basis of understanding of and attitudes towards agriculture, risk, nature and technology. Neglecting the values-based assumptions underlying these decisions can lead to poor decision-making, through misunderstanding the issues at hand, and public and stakeholder backlash resulting from disagreements over values.Bozeman & Sarewitz (2005) consider this problem in a framework of ‘market failures'' and ‘public failures''. GM crops have exhibited both. Market failures are exemplified by the loss of trade with the EU owing to different regulatory standards and levels of caution (PIFB, 2006). Furthermore, there has been a decline in the number of GM crops approved for interstate movement in the USA since 2001. Public failures result from incongruence between actions by decision-makers and the values of the public. Public failures are exemplified by the anti-GM sentiment in the labelling of organic foods in the USA and court challenges to the biosafety review of GM crops by the USDA''s Animal and Plant Health Inspection Service (McHughen & Smyth, 2008). These lawsuits have delayed approval of genetically engineered alfalfa and sugar beet, thus blurring the distinction between public and market failures. Public failures will probably ensue if TagMo crops slip into the market under the radar without adequate oversight.The possibility of public failures with TagMo crops highlights the benefits of an anticipatory governance-based approach, and will help to ensure that the technology meets societal needsAnticipatory governance is a framework with principles that are well suited to guiding TagMo-related oversight and to helping to avoid public failures. It challenges an understanding of technology development that downplays the importance of societal factors—such as implications for stakeholders and the environment—and argues that societal factors should inform technology development and governance from the start (Macnaghten et al, 2005).Anticipatory governance uses three principles: foresight, integration of natural and social science research, and upstream public engagement (Karinen & Guston, 2010). The first two principles emphasize proactive engagement using interdisciplinary knowledge. Governance processes that use these principles include real-time technology assessment (Guston & Sarewitz, 2002) and upstream oversight assessment (Kuzma et al, 2008b). The third principle, upstream public engagement, involves stakeholders and the public in directing values-based assumptions within technology development and oversight (Wilsdon & Wills, 2004). Justifications for upstream public engagement are substantive (stakeholders and the public can provide information that improves decisions), instrumental (including stakeholders and the public in the decision-making process leads to more trusted decisions) and normative (citizens have a right to influence decisions about issues that affect them).TagMo crop developers seem to be arguing for a ‘process-based'' exclusion of TagMo crops from regulatory oversight, without public knowledge of their development or ongoing regulatory communication. We propose that the discussion about how to regulate TagMo crops should be open, use public engagement and respect several criteria of oversight (Kuzma et al, 2008a). These criteria should include not only biosafety, but also broader impacts on human and ecological health and well-being, distribution of health impacts, transparency, treatment of intellectual property and confidential business information, economic costs and benefits, as well as public confidence and values.We also propose that the CFRB should be a starting point for TagMo oversight. The various categories of TagMo require an approach that can discern and address the risks associated with each application. The CFRB allows for such flexibility. At the same time, the CFRB should improve public engagement and transparency, post-market monitoring and some aspects of technical risk assessment.As we have argued, TagMo is on the verge of being broadly implemented to create crop varieties with new traits, and this raises many oversight questions. First, the way in which TagMo technologies will be classified and handled within the US regulatory system has yet to be determined. As these decisions are complex, values-based and have far-reaching implications, they should be made in a transparent way that draws on insights from the natural and social sciences, and involves stakeholders and the public. Second, as products derived from TagMo technologies will soon reach the marketplace, it is important to begin predicting and addressing potential regulatory challenges, to ensure that oversight systems are in place. The possibility of public failures with TagMo crops highlights the benefits of an anticipatory governance-based approach, and will help to ensure that the technology meets societal needs.So far, the EU has emphasized governance approaches and stakeholder involvement in the regulation of new technologies more than the USA. However, if the USA can agree on a regulatory system for TagMo crops that is the result of open and transparent discussions with the public and stakeholders, it could take the lead and act as a model for similar regulation in the EU and globally. Before this can happen, a shift in US approaches to regulatory policy would be needed.? Open in a separate windowJennifer KuzmaOpen in a separate windowAdam Kokotovich     

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. I. Soil-surface-active invertebrates

The effects of herbicide management of genetically modified herbicide-tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil-surface-active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface-active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.     

A novel approach to the use of genetically modified herbicide tolerant crops for environmental benefit

The proposed introduction of genetically modified herbicide tolerant (GMHT) crops, with claims of improved weed control, has prompted fears about possible environmental impacts of their widespread adoption, particularly on arable weeds, insects and associated farmland birds. In response to this, we have developed a novel weed-management system for GMHT sugar beet, based on band spraying, which exploits the flexibility offered by the broad-spectrum partner herbicides. Here, we show the results from two series of field experiments which, taken together, demonstrate that, by using this system, crops can be managed for enhanced weed and insect biomass without compromising yield, thus potentially offering food and shelter to farmland birds and other wildlife. These results could be applicable widely to other row crops, and indicate that creative use of GMHT technology could be a powerful tool for developing more sustainable farming systems in the future.     

Relevance of genetically modified crops in light of future environmental and legislative challenges to the agri-environment

A key challenge for countries like Ireland up to 2030 is to produce sufficient supplies of food, feed and fuel, without compromising on public health or negatively impacting the environment. As we progress through the technology era, certain agricultural technologies [e.g. genetically modified (GM) crops] have been championed to maximise production while minimising environmental impact. Yet, multiple arguments have been made to counter such a claim, which has led to a polarisation of opinions and a plethora of generic commentaries being made in regard to the impact of this technology. Yet, few studies within the European Union (EU) have conducted a critical needs analysis to assess the potential of specific GM traits in light of issues, such as climate change, increased environmental legislation (e.g. EU Water Framework, Nitrates Directive, proposed reform to the Pesticide Directive and Common Agricultural Policy reform), mitigating biodiversity loss and sustainable biofuel production. The goal of this study is to collate a register of GM traits such that a list of potential GM crops could be prioritised against the backdrop of the challenges facing the tillage sector. Clearly, the crops with the most significant potential for genetic modification are those that are grown widely and/or receive high applications of pesticides and fertilisers (e.g. potato, wheat, barley and maize). GM traits with significant agronomic potential include late blight resistant potato, Fusarium head blight resistant wheat and Septoria resistant wheat and herbicide‐tolerant winter oilseed rape and maize. Following on from these, crops with enhanced nitrogen‐use efficiency could provide significant input to the tillage sector in light of EU‐based restrictions on nitrogen usage, crops with elevated protein content could offset the costs of imported animal feed and crops with modified oil content/lignocellulose composition could assist in biodiesel/bioenergy production at a regional level. This study is relevant to other European countries that cultivate similar crops and like Ireland, are facing multiple challenges to their tillage sector in the near future.     

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. II. Within-field epigeal and aerial arthropods

The effects of the management of genetically modified herbicide-tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long-term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.     

The release of genetically modified crops into the environment. Part II. Overview of ecological risk assessment

Despite numerous future promises, there is a multitude of concerns about the impact of GM crops on the environment. Key issues in the environmental assessment of GM crops are putative invasiveness, vertical or horizontal gene flow, other ecological impacts, effects on biodiversity and the impact of presence of GM material in other products. These are all highly interdisciplinary and complex issues. A crucial component for a proper assessment is defining the appropriate baseline for comparison and decision. For GM crops, the best and most appropriately defined reference point is the impact of plants developed by traditional breeding. The latter is an integral and accepted part of agriculture. In many instances, the putative impacts identified for GM crops are very similar to the impacts of new cultivars derived from traditional breeding. When assessing GM crops relative to existing cultivars, the increased knowledge base underpinning the development of GM crops will provide greater confidence in the assurances plant science can give on the risks of releasing such crops.     

Invertebrates and vegetation of field margins adjacent to crops subject to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

The effects of management of genetically modified herbicide-tolerant (GMHT) crops on adjacent field margins were assessed for 59 maize, 66 beet and 67 spring oilseed rape sites. Fields were split into halves, one being sown with a GMHT crop and the other with the equivalent conventional non-GMHT crop. Margin vegetation was recorded in three components of the field margins. Most differences were in the tilled area, with fewer smaller effects mirroring them in the verge and boundary. In spring oilseed rape fields, the cover, flowering and seeding of plants were 25%, 44% and 39% lower, respectively, in the GMHT uncropped tilled margins. Similarly, for beet, flowering and seeding were 34% and 39% lower, respectively, in the GMHT margins. For maize, the effect was reversed, with plant cover and flowering 28% and 67% greater, respectively, in the GMHT half. Effects on butterflies mirrored these vegetation effects, with 24% fewer butterflies in margins of GMHT spring oilseed rape. The likely cause is the lower nectar supply in GMHT tilled margins and crop edges. Few large treatment differences were found for bees, gastropods or other invertebrates. Scorching of vegetation by herbicide-spray drift was on average 1.6% on verges beside conventional crops and 3.7% beside GMHT crops, the difference being significant for all three crops.     

The release of genetically modified crops into the environment. Part I. Overview of current status and regulations

In the past 6 years, the global area of commercially grown, genetically modified (GM) crops has increased more than 30-fold to over 52 million hectares. The number of countries involved has more than doubled. Especially in developing countries, the GM crop area is anticipated to increase rapidly in the coming years. Despite this high adoption rate and future promises, there is a multitude of concerns about the impact of GM crops on the environment. Regulatory approaches in Europe and North America are essentially different. In the EU, it is based on the process of making GM crops; in the US, on the characteristics of the GM product. Many other countries are in the process of establishing regulation based on either system or a mixture. Despite these differences, the information required for risk assessment tends to be similar. Each risk assessment considers the possibility, probability and consequence of harm on a case-by-case basis. For GM crops, the impact of non-use should be added to this evaluation. It is important that the regulation of risk should not turn into the risk of regulation. The best and most appropriate baseline for comparison when performing risk assessment on GM crops is the impact of plants developed by traditional breeding. The latter is an integral and accepted part of agriculture.     

Presence of potential allergy-related linear epitopes in novel proteins from conventional crops and the implication for the safety assessment of these crops with respect to the current testing of genetically modified crops

Mitochondria of cytoplasmic male sterile crop plants contain novel, chimeric open reading frames. In addition, a number of crops carry endogenous double-stranded ribonucleic acid (dsRNA). In this study, the novel proteins encoded by these genetic components were screened for the presence of potential binding sites (epitopes) of allergy-associated IgE antibodies, as was previously done with transgenic proteins from genetically modified crops. The procedure entails the identification of stretches of at least six contiguous amino acids that are shared by novel proteins and known allergenic proteins. These stretches are further checked for potential linear IgE-binding epitopes. Of the 16 novel protein sequences screened in this study, nine contained stretches of six or seven amino acids that were also present in allergenic proteins. Four cases of similarity are of special interest, given the predicted antigenicity of the identical stretch within the allergenic and novel protein, the IgE-binding by a peptide containing an identical stretch reported in literature, or the multiple incidence of identical stretches of the same allergen within a novel protein. These selected stretches are present in novel proteins derived from oilseed rape and radish (ORF138), rice (dsRNA), and fava bean (dsRNA), and warrant further clinical testing. The frequency of positive outcomes and the sizes of the identical stretches were comparable to those previously found for transgenic proteins in genetically modified crops. It is discussed whether novel proteins from conventional crops should be subject to an assessment of potential allergenicity, a procedure which is currently mandatory for transgenic proteins from genetically modified crops.     

A new method for evaluating flowering synchrony to support the temporal isolation of genetically modified crops from their wild relatives

Hybridization between crops and their wild relatives potentially threatens the genetic identity of the wild plants, particularly in the case of genetically modified crops. Only a few studies have examined the use of temporal isolation to prevent hybridization, and the indices used in those studies, (e.g., the days of flowering overlap), are not precise to evaluate the degree of synchrony in flowering. Here we propose a flowering similarity index that can compare the degree of flowering synchrony between two relevant species and measure the efficiency of temporal isolation. The results showed that the flowering similarity index predicts the likelihood of hybridization much better than the number of flowering-overlap days, regardless of different flowering patterns among cultivars. Thus, temporal isolation of flowering or flowering asynchrony is the most effective means in preventing hybridization between crops and their wild relatives.     

Responses of plants and invertebrate trophic groups to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

Effects of genetically modified herbicide-tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10-fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock-on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.     

Flash-photolysis studies of the electron transfer from genetically modified spinach plastocyanin to photosystem I.

Plastocyanin (Pc) has been modified by site-directed mutagenesis at two separate electron-transfer (ET) sites: Leu-12-Glu at a hydrophobic patch, and Tyr-83-His at an acidic patch. The reduction potential at pH 7.5 is decreased by 26 mV in Pc(Leu-12-Glu) and increased by 35 mV in Pc(Tyr-83-His). The latter mutant shows a 2-fold slower intracomplex ET to photosystem I (PSI) as expected from the decreased driving force. The affinity for PSI is unaffected for this mutant but is drastically decreased for Pc(Leu-12-Glu). It is concluded that the hydrophobic patch is more important for the ET to PSI.     

Respiratory tract gene transfer. Transplantation of genetically modified T-lymphocytes directly to the respiratory epithelial surface.

To evaluate the strategy for potentially treating respiratory disorders with genetically modified T-lymphocytes, the interleukin-2 (IL-2)-dependent murine T-cell line, CTLL2, was genetically altered with the Escherichia coli beta-galactosidase (beta-gal) gene (lacZ) in vitro with a retroviral vector and the modified T-cells were transplanted directly to the respiratory epithelial surface of syngeneic C57Bl/6 mice. Southern and Northern analyses confirmed that the neomycin-selected modified T-cells contained and expressed the lacZ gene. The fate of the modified T-cells (CTLL2/lacZ) was followed by flow cytometry with T-cell surface marker Thy1.2 and fluorescent beta-gal analysis. One day after transplantation (7.5 x 10(5) CTLL2/lacZ T-cells/g of body weight), 95 +/- 3% of the Thy1.2+ T-cells recovered from respiratory epithelial lining fluid (ELF) were beta-gal+. Importantly, the modified T-cells remained in the lung for some time; at 3 days, Thy1.2+ beta-gal+ T-cells represented 63 +/- 12% of ELF Thy1.2+ T-cells and 59 +/- 6% of Thy1.2+ T-cells recovered from the whole lung. At 7 days, 33 +/- 8% of the Thy 1.2+ cells in ELF and 75 +/- 6% of the Thy1.2+ cells in whole lung were Thy1.2+ beta-gal+. In contrast, the proportion of the Thy1.2+ beta-gal+ T-cells in the spleen, the major extrapulmonary lymphatic organ, never rose above 3 +/- 1% of the total Thy1.2+ cells. The number of Thy1.2+ beta-gal+ T-cells in the lung could be modified by the systemic administration of IL-2, with whole lung Thy1.2+ beta-gal+ T-cells increasing 4.6-fold 3 days after transplantation, compared with non-IL-2-treated animals. These studies suggest that direct transplantation of genetically modified T-cells into the lung is feasible and represents a viable strategy for lung-specific gene transfer.     

Stop worrying; start growing. Risk research on GM crops is a dead parrot: it is time to start reaping the benefits of GM

Opponents of genetically modified crops continue to raise concerns about risk, despite 20 years of research disproving their claims. Science should close the book on risk research and turn to studying the economic and environmental benefits of agricultural biotechnologyEver since the Asilomar Conference on ‘Recombinant DNA'' in February 1975, regulatory policies relating to recombinant DNA technology have focused on the idea that this technology implies threats to human health and the environment [1]. As a consequence, the explicit goal of these policies is to protect society and nature from an assumed hazard, or, if protection is not possible, at least to delay the implementation of the technology until scientific evidence shows it to be harmless. These policies were widely accepted at the time, as public concerns were, and still are, important. As time has gone by, the evidence for negative impacts of genetically modified (GM) crops has become weaker. However, the regulatory policies within the EU are still rigid enough to prevent most GM crops from leaving the confined laboratory setting; should some candidate occasionally overcome the hurdles posed by these policies, the precautionary principle is invoked in order to ensure further delaying in its use in the field. The reason for this over-cautious approach is widespread public resistance to GM crops, caused and amplified by interested groups that are opposed to the technology and invest heavily into lobbying against it.As time has gone by, the evidence for negative impacts of genetically modified (GM) crops has become weakerAgainst this background of political resistance, it is no surprise that the risks, costs and potential disadvantages of not growing GM crops have received little or no attention. These disadvantages become increasingly relevant as the scientific arguments for the prevailing resistance to GM crops become weaker. Twenty-five years of risk research on GM crops have established beyond reasonable doubt that biotechnology is not per se riskier than conventional plant breeding technologies [2]. The whole seemingly endless discussion about purported risks of GM crops is akin to the famous Monty Python sketch in which John Cleese is trying to return a dead parrot to shopkeeper Michael Palin, who, despite the evidence, insists that the bird is well, alive and “pining for the fjords”. Instead, we need to highlight the opportunities missed by not accepting GM crops. These include lost revenues for farmers, breeding companies and consumers, brain drain and lost technology innovations, reduced agricultural productivity and sustainability, foregone health benefits, especially reducing malnutrition, and many more realized or expected virtues of GM crops [3].In a report from 2010, the EC […]concluded that biotechnology is not per se riskier than conventional plant breeding technologiesRisk assessment and risk analysis of genetically modified organisms (GMOs) is governed by internationally accepted guidelines, developed by the Codex Alimentarius Commission (www.fao.org). One leading principle is the concept of substantial equivalence, which stipulates that any new GM variety should be assessed for its safety by comparing it with an equivalent, conventionally bred variety that has an established history of safe use [4]. Despite the fact that the Codex Alimentarius guidelines are globally endorsed, the authorization procedure for GMOs differs substantially between national jurisdictions. Europe stands out as being considerably more restrictive than countries in North and South America and parts of Asia, for example. Within the European Union (EU), a common regulatory legal framework such as Regulation (EC) No. 1829/2003, governs GM crops intended for human food and animal feed. Any party seeking approval for an edible GM crop must provide extensive scientific documentation that demonstrates that the food or feed derived thereof has no adverse effects on human and animal health or the environment, does not mislead the consumer, or does not differ from the food it is intended to replace to such an extent that its normal consumption would be nutritionally disadvantageous for the consumer.The risk assessment is conducted and compiled by the applicant, and is evaluated by the GMO Panel of the European Food Safety Authority (EFSA). The opinion of the panel should form the scientific basis when member states provide other legitimate arguments and cast their votes in the Standing Committee for Food and Animal Health of the European Commission. Thus, the decision to approve a particular GMO should be on the basis of scientific grounds. By the same logic, one might take for granted that only GMOs that have been shown to have adverse effects on animal or human health or the environment will not receive approval. In practice, however, the decision whether or not to approve a particular GMO is not solely a scientific issue. Several member states vote, in principle, against approval, irrespective of the scientific opinion delivered by the EFSA [5]. In recognition of this dead-lock, the European Commission (EC) has suggested that individual member states should have the right to restrict cultivation of a given GM crop even if there are no scientifically established risks, that is, to adopt restrictions on the basis of socio-economical or ethical grounds [6].In addition to the scientific documentation provided by the applicants who seek approval of a GM crop, public research has investigated the risks of GMOs during the past 15 years. The Directorate-General Research under the EC has spent €200 million during the past decade on such research, and several member states have initiated national research programmes specifically targeting the potential impact of the very same crops and traits that are in the European approval system [2]. A collaborative working group under the Standing Committee on Agricultural Research (SCAR) has estimated that the funds allocated to national risk research on GMOs in 13 European countries amount to at least €120 million during the past eight years (http://bmg.gv.at/home/Schwerpunkte/Gentechnik/Fachinformation_Allgemeines/SCAR_Collaborative_Working_Group_Risk_Research_on_GMOs).In a report from 2010, the EC summarized the results of 130 research projects involving more than 500 independent research groups and concluded that biotechnology is not per se riskier than conventional plant breeding technologies [2]. Further support for this position comes from the UK Farm-Scale Evaluation (FSE), which studied the potential impact of herbicide-tolerant crops on farmland biodiversity [7]. One insight from the study is that overall changes in agricultural management determine the impact of a crop on biodiversity, rather than the technology or breeding behind the crop itself [8].… it is time to look at the other side of the equation and gauge the possible benefits of adopting and growing GM cropsBetween 2008 and 2009, the EFSA GMO panel evaluated a renewal to permit the continued import, processing and cultivation of maize variety MON810 for food and feed. MON810 expresses the Cry1Ab protein from the soil-borne bacterium Bacillus thuringiensis (Bt), which confers resistance to the European corn borer, and is one of two GM crops approved for cultivation in Europe; it was first approved in 1998. As a basis for its 2009 opinion, the EFSA GMO Panel summarized 48 peer-reviewed papers on the potential risks of MON810 on animal and human health and the environment, in addition to the documentation provided by the company [9]. It found no adverse effects and concluded that MON810 is comparable with its conventionally bred parental lines. The only difference reported was that MON810 has an increased variability in lignin content, in some studies it has been found to be higher and in some studies lower. Similarly, a review by Icoz & Stotzky [10] of studies on the effects of insect-resistant Bt crops on soil ecosystems found no notable detrimental effects on microbes and other organisms in below-ground soil ecosystems. Accordingly, the authors concluded that “…available funding would be better spent on studies of the potential risks associated with the release of transgenic plants genetically engineered to express pharmaceutical and industrial products that, in contrast to Cry proteins, are targeted primarily to human beings and other higher eukaryotic organisms.”If, as 15 years of intense research and risk assessment have shown, GM crops do not pose greater risks for human health or the environment than conventionally bred varieties, it is time to look at the other side of the equation and gauge the possible benefits of adopting and growing GM crops. To that end, Fagerström & Wibe [11] analysed the potential economic consequences for Sweden of farmers not growing GM crops—herbicide-tolerant sugar beet and canola, and late blight-resistant potato—and then extended the analysis to all of the EU. They considered two rough categories of impact: effects that could be evaluated by studying market prices that show impacts for producers on work-force and capital, and demand for fertilizers, pesticides and fuel, and factors related to the cost of keeping GM crops separated from conventionally or organically grown crops during cultivation, harvest, transport, storage and processing. The latter cost arises from the European attitude of regarding GM crops and products as contaminants—as if we were dealing with toxic substances.In 2008, Sweden produced almost 2 million tons of sugar beet grown on approximately 37,000 hectares and with a production value of €70 million. The authors calculated that a shift to herbicide-tolerant sugar beet could have led to a 5–10% increase in yield. Expenditure on seeds would increase from €180 to €210 per hectare, but the cost of herbicides would decrease from €180 to €55. Taken together, the cost of input goods would decrease by 27%.Analysis of the sugar beet shows that the economic value to producers and, by extension, to society is strategically dependent on two factors: the cost of keeping GM sugar separate from conventional sugar, and the public acceptance of GM sugar. The crucial limit was found to be a separation cost of 25% of the price; at this limit, the economic value to society vanishes even if all consumers buy GM products—if public acceptance is 100%. In a realistic scenario the separation cost is ∼10% of the price and the public acceptance is ∼25% of the consumers. Thus, the economic benefit would be €1.3 million, or ∼2% of the total value of sugar beet production. If GM crops enjoyed full public acceptance, and if there were accordingly no costs of separation, the economic gain to society would amount to €10 million; about 14% of the total value of sugar beet production. Approximately 3,000 hectares of arable land—8% of the acreage of sugar beet—would be available for other uses.Similar values apply for potato and canola, so introducing these three GM crops in Sweden would yield an economic value of €30 million annually. In addition, producers would regain 10,000 hectares (ha) of arable land; using official statistics on leasing costs for arable land in Sweden, this has an annual value of approximately €2 million. This adds up to a combined annual value to society of €32 million. The accumulated value of this annual revenue over many years—the so-called capitalized value—is €1–€1.6 billion at an interest rate of 2–3%. The annual gain amounts to approximately 14, 11 and 5% of the production value for sugar beet, canola and potato, respectively. EU-wide, a shift to these three GM crops would yield a gain of ∼€2 billion annually, and would save ∼645,000 ha, which corresponds to a capitalized value in the range of €80–€120 billion.These calculations presuppose full public acceptance of GM crops; that is, a world in which consumers perceive GM crops as equal to or better than non-GM varieties. In addition, the results rest on the assumption that the benefits to the environment such as decreased use of pesticides can be measured by the cost of the pesticides. Presumably, this is an underestimate of the environmental benefits, and the societal value is therefore probably greater than the figures presented above.Other studies address the problem of missed economic benefits, often using economic models similar to those used by Fagerström & Wibe [11]. Generally, they confirm the results discussed above: the magnitudes of the unrealized benefits are similar. Matin Qaim, an agricultural economist at Göttingen University, Germany, for example, presented figures for Bt cotton adoption that would entail global welfare gains in the range of €0.5–€1.0 billion per year [12]. The biggest impact occurs in China, but India, where the relevant technology was more recently commercialized, has been catching up rapidly. It is estimated that the widespread adoption of Bt cotton in India and other countries of South Asia will result in further regional welfare gains on the order of €1 billion per year.The benefits of adopting GM oilseeds and maize are amplified by the larger international markets on which they are traded. While the annual global welfare gains at the present moderate level of adoption are estimated at €3.5 billion [13], this figure could reach approximately €7.5 billion with widespread international adoption of herbicide-tolerance and insect-resistant crops [12]. However, it is also noted that a ban on production and imports by the EU could reduce these global gains by two-thirds owing to unrealized benefits for domestic consumers and the far-reaching influence of EU policies on international trade flows and production decisions in other regions.… not adopting modern breeding tools—including biotechnology—will probably hamper the European agricultural systems facing a warmer and more variable climateLarge global welfare gains are projected for GM rice as well. Assuming that there is moderate adoption of GM rice in rice-producing regions, the combined global welfare gains are estimated to be in the region of €5 billion per year for Bt-carrying, herbicide-resistant and drought-tolerant rice varieties, with India and China gaining the most. Projected welfare gains in China alone could reach more than €3 billion when first-generation GM rice technologies are widely adopted. Both studies [11,12] highlight that available analyses probably provide lower estimates of the global welfare effects of GM crops, because other environmental and health benefits have not been properly quantified.Agriculture is blamed frequently for biodiversity loss. Several recent studies, however, demonstrate that the design of the agricultural landscape, with refuges for non-crop species, intercropping and crop rotation, can counterbalance the effects of an intensified agriculture system [14]. Hence, one of the most important consequences of better yields from herbicide and pest-resistant GM crops in Europe would be that the surplus land could be used for refuges to promote biodiversity in the farming landscape and save natural forests from deforestation or wetlands from being drained to make way for farmland. However, regulations regarding cultivation distances, as well as other measures to keep GM crops separate from conventionally bred varieties, lock GM crops into large-scale agricultural practices and, in effect, prevent intercropping. Thus, the principle of non-coexistence limits the scope for farmers to take full advantage of the benefits of present and future GM crops to further reduce the need for pesticides and increase the productivity of farmland. This line of reasoning is supported by a recent study showing that the willingness of farmers to adopt GM crops is substantially hampered by the costs and uncertainties associated with coexistence regulations, despite lower costs for chemicals [15].Historically, cereal crop varieties have been replaced by new varieties on average every 5–10 years [16]. The reasons for this turnover vary, but one underlying drive for crop replacement is the rapid loss of resistance traits. In order to maintain yield levels, farmers must either increase their use of chemicals to kill pests, or change to a new crop variety; hence the continuous breeding for resistance traits. Imminent climate changes will put further constraints on agricultural production, including an increasing need for faster and more efficient plant breeding to adapt crops to more variable local conditions [17]. If breeders fail in this regard, agro-chemical use will increase and Europe will become more dependent on imports. In Europe, the spatial variation in rainfall is expected to increase: Northern Europe can expect a more humid climate, which will constrain crop production owing to the increased severity of biotic stresses such as insect pests, fungal pathogens and the invasion of alien, noxious species, whereas crop production in southern Europe will have to be adapted to drier conditions [18,19]. Thus, not adopting modern breeding tools—including biotechnology—will probably hamper the European agricultural systems facing a warmer and more variable climate [20].Legislation that determines what constitutes a GMO was ratified in 2001. In a legal sense, a GMO is defined as an organism in which the genetic material has been altered in a way that does not occur naturally by mating or natural recombination, and refers to both plants and animals, except humans. In practice, a GMO is defined by an addendum to the Directive 2001/18EC, which lists the techniques that give rise to a GMO. Since the Directive 2001/18EC was ratified, ten years have passed, and technology has progressed further. Many of the techniques listed in the addendum have been improved or are obsolete. A recent report to the EC by the Joint Research Centre [21] describes new methods, their possible applications for plant breeding and potential implications for agriculture. One common aspect of the new techniques is that many involve the use of recombinant DNA or RNA molecules in one phase of the breeding process; however, these recombinant molecules are not present in the final product and are commonly not transmitted to the next generation.… the burden of EU legislation for GM technologies is completely out of proportion compared with other science-based endeavoursInterestingly, European scientists at public and private institutions are at the forefront of technological development concerning new breeding. In this respect the situation is similar to the history of plant transformation technologies first developed at European universities [22], but now mainly used outside Europe [23]. By way of illustration, BASF, the company that developed the Amflora potato, announced recently that it is halting research on GM crops in Europe. Ultimately, the development and success of scientific know-how and new technology in Europe, as well as the adoption of new techniques and crops, will depend on the decisions made by European legislators who are discussing GM technologies and their ratification.As a comparison, other genetically engineered products, such as biopharmaceuticals, are approved for humans and food-producing animals after ordinary science-based safety assessments [23], without the ideological stigmatization and biased decision-making processes seen for GM crops.Our review of the state-of-affairs of GM crops in Europe raises several fundamental issues. First, the burden of EU legislation for GM technologies is completely out of proportion compared with other science-based endeavours. This is manifested by the substantially longer time required for a GM product to reach approval within the European legal framework (45 months), compared with GMO-exporting countries such as the USA, Canada or Brazil (27 months) [24]. In addition, these European approval times are only valid for importing commodities; approvals for cultivation in Europe take substantially longer. It took 14 years for the Amflora potato, for example, which is only the second GM crop to be approved in Europe. Not only are rules more restrictive in Europe, but only the largest companies in the seed and plant breeding business have the financial capacity to go through the lengthy and costly procedure required for approving a GM crop variety. This hampers small and medium business and prevents business spin-offs from plant research.Second, research priorities in regard to the environmental impacts of agriculture are not directed in a productive way; risk research in Europe is not helping to develop sustainable agriculture for the future. The paradigm that stipulates that biotechnology is inherently risky, and singles out one plant breeding technology as the basis for risk research, is putting a massive regulatory burden on a technology that could enhance sustainability. As a consequence, any future risk research on GMOs in Europe should address the costs of this burden and the risks of not using biotechnology. We conclude that the research programmes set up in the EU to address the potential risks of GM crops are no longer scientifically motivated inquiries. The scientific community has already settled the relevant questions regarding potential risks associated with GM crops approved under legislation; what is going on is a political game. In this game, the so-called precautionary principle is used, in absurdum, to delay any launch of a GM crop far beyond the limit of reasonable scientific doubts.Third, it is time to acknowledge the distinct imbalance with respect to the costs and benefits of GM crops: lobbyists who benefit from demonizing GM crops are not the ones who have to carry the costs. Hence, it is not the hyped risks of GM crops that are a problem in the EU, it is the submissive attitude of politicians and policy-makers towards organizations who insist that GM crops are risky. It is then ordinary consumers who pay the costs and do not receive the benefits. This submissiveness manifests in the prevailing policy that GM products should be kept separate from non-GM products, as well as the incessant calls for regulations about labelling and traceability. As shown above, the potential benefit to the European economy from adopting GM crops is substantial. But these potential benefits vanish altogether when the costs of maintaining separation and consumer resistance are brought into play as a result of misinformation campaigns.… research priorities in regard to the environmental impacts of agriculture are not directed in a productive way…Risk research on GM crops in Europe has to come to an end, as do futile battles about disasters that will not happen. A dead parrot is a dead parrot, both in Monty Python sketches and in science. The way to sustainable and productive agriculture is not by maintaining expensive, parallel production systems, using different sets of crop varieties, and relying on expensive regulations for their coexistence. Instead, agricultural systems should use the best available technology at all stages, including plant breeding. It is clear that the approval and decision process within the EU for GM crops is not science-based. The risk assessment and approval process, where the outcome is dominated by the opinions of a few self-interested stakeholder organizations with special interests is unique. It is alarming that decision-making bodies kow-tow to this non-science-based paradigm.? Open in a separate windowTorbjörn FagerströmOpen in a separate windowChristina DixeliusOpen in a separate windowUlf MagnussonOpen in a separate windowJens F Sundström     

Prevention of aerobic spoilage of maize silage by a genetically modified killer yeast, Kluyveromyces lactis, defective in the ability to grow on lactic acid.

In this study, we propose a new process of adding a genetically modified killer yeast to improve the aerobic stability of silage. Previously constructed Kluyveromyces lactis killer strain PCK27, defective in growth on lactic acid due to disruption of the gene coding for phosphoenolpyruvate carboxykinase, a key enzyme for gluconeogenesis, inhibited the growth of Pichia anomala inoculated as an aerobic spoilage yeast and prevented a rise in pH in a model of silage fermentation. This suppressive effect of PCK27 was not only due to growth competition but also due to the killer protein produced. From these results, we concluded that strain PCK27 can be used as an additive to prolong the aerobic stability of maize silage. In the laboratory-scale experiment of maize silage, the addition of a killer yeast changed the yeast flora and significantly reduced aerobic spoilage.