non-GM Crops Research Articles

Preliminary development of a genetic strategy to prevent transgene escape by blocking effective pollen flow from transgenic plants.

Genetic modification (GM) of plants has great potential in the production of food and industrial compounds, and in molecular pharming. One of the greatest public concerns regarding this technology is effective pollen flow, in which wind- or insect-borne transgenic pollen is able to fertilise either non-GM crops of the same species, or closely related weed species, and lead to viable seed formation. In this paper we describe a novel concept, based on epigenetic inheritance (imprinting) and post-transcriptional gene silencing (PTGS)/RNA interference (RNAi), designed to prevent transgene escape via pollen flow from transgenic plants. A key advantage of this strategy is that it would allow all seeds from self-pollinated transgenic plants to be harvested and re-sown, without the need for specific treatments, while retaining all of the transgenes present in the parent. Thus, this strategy is not a Genetic Use Restriction Technology (GURT) and if implemented would not prevent seed saving by end-users.

Governing the Co-Existence of GM Crops: Ex-Ante Regulation and Ex-Post Liability under Uncertainty and Irreversibility

The future institutional environment for the co-existence of genetically modified (GM) crops, conventional crops and organic crops in Europe combines measures of ex-ante regulation and ex-post liability rules. Against this background we ask the following two questions: How does ex-ante regulation and ex-post liability under irreversibility and uncertainty affect the adoption of GM crops? What are the implications for regional agglomeration of GM and non-GM crops? Ex-ante regulations and ex-post liabilities for using GM crops will induce additional costs. These costs are modelled in a classical way. The model is advanced by including irreversibility and uncertainty and taking into account transaction costs of negotiating possible solutions with neighbouring farmers which are assumed to be partially irreversible. The results show that the design of ex-ante regulation and ex-post liability increases the value of waiting and results in less immediate adoption of the GM technology. Additionally, the rules and regulations in the EU do provide incentives for the regional agglomeration of GM and non-GM crops that are mainly driven by the irreversibility effect of the ex-ante regulatory and ex-post liability costs.

EU biotech crop regulations and environmental risk: a case of the emperor's new clothes?

European Union Commissioner for the Environment Stavros Dimas recently hailed 'upgraded' non-genetically modified (GM) crops as an alternative to GM crops. A comparative analysis of the environmental risks associated with such non-GM herbicide-resistant crops and GM herbicide-resistant crops is presented here. The analysis highlights serious weaknesses in the European Union (EU) regulatory framework, and the contradictory policy of the EU Commission on the precautionary principle is also shown. The continued political stance of ignoring these regulatory and policy inconsistencies is examined and found to be flawed. It is postulated that, even in the face of these flaws and coupled with recent statements from the UK drawing attention to inconsistencies in the EU regulatory framework, the EU will continue to ignore the real and present environmental risks associated with upgraded non-GM crops for biopolitical reasons.

Sources of uncertainty in the quantification of genetically modified oilseed rape contamination in seed lots

Testing of seed and grain lots is essential in the enforcement of GM labelling legislation and needs reliable procedures for which associated errors have been identified and minimised. In this paper we consider the testing of oilseed rape seed lots obtained from the harvest of a non-GM crop known to be contaminated by volunteer plants from a GM herbicide tolerant variety. The objective was to identify and quantify the error associated with the testing of these lots from the initial sampling to completion of the real-time PCR assay with which the level of GM contamination was quantified. The results showed that, under the controlled conditions of a single laboratory, the error associated with the real-time PCR assay to be negligible in comparison with sampling error, which was exacerbated by heterogeneity in the distribution of GM seeds, most notably at a small scale, i.e. 25 cm3. Sampling error was reduced by one to two thirds on the application of appropriate homogenisation procedures.

A Proposed Risk Assessment Method for Genetically Modified Plants

An essential step in the development of products based on genetically modified plants (GMPs) is an assessment of safety, including an evaluation of the potential impact of the crop and practices related to its cultivation on the environment and human or animal health. The purpose of this safety assessment is to compare information about the GMP with that from a non-GM crop. However, at present this risk analysis may be faulty because there is no widely accepted and specific risk assessment method to evaluate GMPs that uses quantifiable parameters and allows for a comparative analysis among different technologies. This paper introduces a risk analysis method that focuses on the identification and evaluation of risks associated with the field release and cultivation of GMPs. Two tools bolster this proposed risk assessment method: (1) worksheets to compile Evidence of Risks, and (2) a Matrix of Assessment. The first tool identifies potential hazards related to the use of a specific GMP. This preformatted worksheet assigns values to the level of risk and its significance in terms of the activity to be developed. The second tool provides a structure to observe the potential hazards that illustrates what approach supports the use of GMPs in a manner as safe as any other traditional technology. To better understand this proposed risk assessment method, it is presented in a digital format (www.cnpma.embrapa.br/forms/gmp_ram.php3) (GMPRAM v.1.1. software) where the two tools are linked so that the user can fill in the worksheets and automatically observe the results in the matrix. Compared to current processes, this proposed method represents a less subjective and more transparent process for risk assessment.

Directed microspore‐specific recombination of transgenic alleles to prevent pollen‐mediated transmission of transgenes

A major challenge for future genetically modified (GM) crops is to prevent undesired gene flow of transgenes to plant material intended for another use. Recombinase-mediated auto excision of transgenes directed by a tightly controlled microspore-specific promoter allows efficient removal of either the selectable marker gene or of all introduced transgenes during microsporogenesis. This way, transgene removal becomes an integral part of the biology of pollen maturation, not requiring any external stimulus such as chemical induction by spraying. We here show the feasibility of engineering transgenic plants to produce pollen devoid of any transgene. Highly efficient excision of transgenes from tobacco pollen was achieved with a potential failure rate of at most two out of 16,800 seeds (0.024%). No evidence for either premature activation or absence of activation of the recombinase system was observed under stress conditions in the laboratory. This approach can prevent adventitious presence of transgenes in non-GM crops or related wild species by gene flow. Such biological containment may help the deployment and management of coexistence practices to support consumer choice and will promote clean molecular farming for the production of high-value compounds in plants.

Assessment of Real-time PCR Based Methods for Quantification of Pollen-mediated Gene Flow from GM to Conventional Maize in a Field Study

Maize is one of the main crops worldwide and an increasing number of genetically modified (GM) maize varieties are cultivated and commercialized in many countries in parallel to conventional crops. Given the labeling rules established e.g. in the European Union and the necessary coexistence between GM and non-GM crops, it is important to determine the extent of pollen dissemination from transgenic maize to other cultivars under field conditions. The most widely used methods for quantitative detection of GMO are based on real-time PCR, which implies the results are expressed in genome percentages (in contrast to seed or grain percentages). Our objective was to assess the accuracy of real-time PCR based assays to accurately quantify the contents of transgenic grains in non-GM fields in comparison with the real cross-fertilization rate as determined by phenotypical analysis. We performed this study in a region where both GM and conventional maize are normally cultivated and used the predominant transgenic maize Mon810 in combination with a conventional maize variety which displays the characteristic of white grains (therefore allowing cross-pollination quantification as percentage of yellow grains). Our results indicated an excellent correlation between real-time PCR results and number of cross-fertilized grains at Mon810 levels of 0.1-10%. In contrast, Mon810 percentage estimated by weight of grains produced less accurate results. Finally, we present and discuss the pattern of pollen-mediated gene flow from GM to conventional maize in an example case under field conditions.

Co-existence of agricultural production systems

Strategies and best practices for the co-existence of GM and non-GM crops need to be developed and implemented with the participation of farmers and other stakeholders. According to the principle of 'subsidiarity', decisions should be made by the lowest authority possible. When applying this concept to the case of GM crops, the affected society should determine their use and management in a regional decision-making process. Public participation is better accomplished at a lower level, and democratic deficits in decision-making on GMOs are better resolved, enabling farmers to manage or avoid GM crops. Ultimately, voluntary GMO-free zones might be a tool for sustainable co-existence and GM-free production and GMO-free zones might create a specific image for marketing regional products and services, such as tourism.

Methodological scheme for designing the monitoring of genetically modified crops at the regional scale

According to EC regulations the deliberate release of genetically modified (GM) crops into the agro-environment needs to be accompanied by environmental monitoring to detect potential adverse effects, e.g. unacceptable levels of gene flow from GM to non-GM crops, or adverse effects on single species or species groups thus reducing biodiversity. There is, however, considerable scientific and public debate on how GM crops should be monitored with sufficient accuracy, discussing questions of potential adverse effects, agro-environmental variables or indicators to be monitored and respective detection methods; Another basic component, the appropriate number and location of monitoring sites, is hardly considered. Currently, no consistent GM crop monitoring approach combines these components systematically. This study focuses on and integrates spatial agro-environmental aspects at a landscape level in order to design monitoring networks. Based on examples of environmental variables associated with the cropping of Bt-Maize (Zea maize L.), herbicide-tolerant (HT) winter oilseed rape (Brassica napus L.), HT sugar beet (Beta vulgaris L.), and starch-modified potato (Solanum tuberosum L.), we develop a transferable framework and assessment scheme that comprises anticipated adverse environmental effects, variables to be measured and monitoring methods. These we integrate with a rule-based GIS (geographic information system) analysis, applying widely available spatial area and point information from existing environmental networks. This is used to develop scenarios with optimised regional GM crop monitoring networks.

Consultative Opinion on Liability of Public and Private Actors for Genetic Contamination of Non-GM Crops

An abridged version of the Consultative Opinion is presented here. For details of the full text readers are advised to contact the ICEAC.

Persistence of seeds from crops of conventional and herbicide tolerant oilseed rape ( Brassica napus )

A series of rotation experiments at five sites over four years has explored the environmental and agronomic implications of growing herbicide tolerant oilseed rape and sugar beet. This paper reports on the population dynamics of volunteer rape (Brassica napus). The experiments compared four winter oilseed rape (WOSR) cultivars: a conventional cultivar (Apex) and three developmental cultivars either genetically modified (GM) to be tolerant to glyphosate or glufosinate, or conventionally bred to be tolerant to herbicides of the imidazolinone group. Seed losses at harvest averaged 3575 seeds m(-2) but ranged from less than 2000 up to more than 10000 seeds m(-2). There was a rapid decline in seed numbers during the first few months after harvest, resulting in a mean loss of seeds of 60%. In subsequent seasons, the seedbank declined much more slowly at four of the five sites (ca 20% per year) and the models predicted 95% seed loss after approximately 9 years. Seed decline was much faster at the fifth site. There were no clear differences between the four cultivars in either the numbers of seeds shed at harvest or in their subsequent persistence. The importance of the persistence of GM rape seeds, in the context of the coexistence of GM and non-GM crops and the role of good management practices that minimize seed persistence, are discussed.

The Myth of Coexistence: Why Transgenic Crops Are Not Compatible With Agroecologically Based Systems of Production

The coexistence of genetically modified (GM) crops and non-GM crops is a myth because the movement of transgenes beyond their intended destinations is a certainty, and this leads to genetic contamination of organic farms and other systems. It is unlikely that transgenes can be retracted once they have escaped, thus the damage to the purity of non-GM seeds is permanent. The dominant GM crops have the potential to reduce biodiversity further by increasing agricultural intensification. There are also potential risks to biodiversity arising from gene flow and toxicity to nontarget organisms from herbicide-resistant (HT) and insect-resistant (Bt) crops. Unless whole regions are declared GM agriculture free, the development of distinct systems of agriculture (GM and non-GM) will be impossible as GM agriculture emerges at the expense of all other forms of production.

Safety Risks for Animals Fed Genetic Modified (GM) Plants

GM plants are widely grown all over the world, but many constraints still tend to discourage their use in Europe. Potential risks suggested to be associated with the use of GM are unexpected gene effects, allergenic potential, antibiotic resistance, gene flow. GM feed safety is presently evaluated by adopting the concept of GM substantial equivalence, by comparison with non-GM isogenic crops. Comparison is based on a wide spectrum of chemical components and on livestock performance. From the available experimental data, currently utilized GM plants appear safe and show no effects on animals or animal products. Hence, although they potentially exist, safety risks caused by the use of GM plants appear to be so low as be negligible in comparison with their potential benefits, if appropriately designed. GM plants represent a valuable option for future breeding, to increase yield while reducing the use of pesticides, improve plant adaptation to unfavourable environments, and produce better quality crops, also from a nutritional point of view. Nonetheless, GM crops are novel foods and the assessment of their safety using a scientific sound approach seems essential to protect the environment, as well as the health of humans and livestock.

Spatial aspects of gene flow between rapeseed varieties and volunteers

GENESYS models the effects of regional cropping systems on gene flow between cropped and volunteer rape plants. Its sensitivity to field patterns and cropping system input variables was analysed using Monte Carlo simulations of which the output was analysed by regression trees and linear regressions. The studied simulated output variable was the harvest contamination of conventional crops by genetically modified seeds. The study showed that field characteristics (areas, shapes, distances and orientation) have little effect compared with cropping systems. Gene flow increased with the area of the pollen- and seed-producing field and decreased with the area of the gene-receiving field; it increased for elongated vs. square fields and decreased with the distance between fields. The sensitivity analysis identified the distance and time during which cropping systems influence harvest contamination in various field plants. The harvest purity of a cluster of fields was influenced by the cropping history of the fields located less than 200 to 400 m around the cluster, and of three past years in addition to the ongoing analysed year for major variables such as crop succession or sowing date. The analysis of these major variables pointed to strategies for reducing gene flow, such as increasing the time between successive rape varieties; avoiding high-risk crops such as genetically modified (GM) rape and set-aside in the neighbouring fields for the year preceding the cultivation of a non-GM crop as well as the year during which the non-GM rape is grown; delaying the sowing of non-GM rape.

Evolution of weed beet ( Beta vulgaris L.) seed bank: Quantification of seed survival, dormancy, germination and pre-emergence growth

Weed beet is an important weed of sugar beet crops. Weed and cropped beets can cross easily and the management of weed beet is therefore crucial in the case of the advent of GM sugar beet, especially herbicide-tolerant cultivars, in order to ensure the co-existence of GM and non-GM crops and to avoid the appearance of herbicide-resistant weed beet. The inability of weed beet to compete in most other crops of the rotation makes the seed bank evolution a crucial stage of the life-cycle because in the rotation, sugar beet is at the most cultivated only every 3 years. The present study used seed burial experiments and laboratory analyses to characterise each step of the evolution of the weed beet seed bank and the external factors that could modify seed persistence in the soil. A monthly seed mortality of 10% was observed between October and December, while mortality was nil during the other seasons. Equations were then developed to describe the observed seasonal variations in seed survival. Seed dormancy also varied with season: the proportion of non-dormant seeds increased during winter (appearance of secondary dormancy) and decreased during the remaining seasons (loss of dormancy). In addition, the germinating seeds decreased with seed age and seed depth, while the presence of light stimulated germination. These observations were also translated into equations. Last, the pre-emergence hypocotyl growth and its variability were studied according to seed age, but no significant effect was observed. The results confirm the importance of the effects of cropping system on the evolution of the weed seed bank, especially the effect of soil tillage, which determines the date and conditions of seed burial, seed excavation and germination stimulation.

The co-existence between transgenic and non-transgenic maize in the European Union: a focus on pollen flow and cross-fertilization

The ongoing discussion on the co-existence between genetically modified (GM) and non-GM crops becomes more important in the European Union (EU). With the recent inscription of 17 GM maize varieties in the common EU catalogue of varieties of agricultural plant species, the acreage of transgenic maize for market purposes is expected to increase in some European countries. In the EU, specific tolerance thresholds have been established for the adventitious and technically unavoidable presence of GM material in non-GM produce, and member states are elaborating legal frames to cope with co-existence. As maize is a cross-pollinated crop relying on wind for the dispersal of its pollen, technical management measures will be imposed to reduce cross-fertilization between transgenic and non-transgenic maize. Various biological, physical and analytical parameters have been identified to play a role in the study of cross-fertilization in maize. This variability may hamper the comparison between research results and may complicate the definition of appropriate isolation distances and/or pollen barriers in order to limit out-crossing. The present review addresses these parameters and proposes containment measures in order to not exceed the legal labeling thresholds in maize.

Unleashing problem solvers: from assessment to designing research

|^an transgenes be kept on a leash? ask Marvier ^-^ and Van Acker in preceding review article (pp 99-106). No, they answer, the movement of transgenes beyond their intended destination is a virtual certainty, and furthermore it is unlikely that transgenes can be retracted once they have escaped. Would these bold statements engage students, revealing realities and complexities of genetically modified (GM) crops? How can we use critical analyses presented by these authors to guide our undergraduates towards developing their own analytical skills? Students' abilities to analyze controversial subjects are often limited by their lack of understanding of basic sci? ence fundamental to issue. In this case, their approach to debate about GM crops may be driven by common misconceptions about, for example, gene expression, traits, or even difference between an allele and a mutation. Students may not know that genes flow between non-GM crops, a normal, commonly occurring process. Hence, a common belief is that traditional methods of crop breeding are completely safe, while all transgenic crops are potentially dangerous (Beringer 2000; CSU 2004). Ideally, we want students to understand body of knowledge surrounding a subject so they can transfer and apply their knowledge to solve novel, complex problems. In this two-step approach to scientific teaching, we use Marvier and Van Acker's paper as context for assessing students' comprehension and problem-solving abilities. We then provide instructors with a framework for thinking about what these assessments mean and how they could form basis of a researchable question.

Genetically modified crops and agricultural landscapes: spatial patterns of contamination

A crucial question facing the global agri-food system is whether genetically modified (GM) crops can co-exist with traditional crops. The purpose of this paper is to clarify how the presence of GM crops and changes in the probability of genetic transfer between crops on an agricultural landscape can result in non-GM crop contamination. To investigate this issue, we develop and analyze a spatial simulation model of GM crop introduction and expansion. The GM crop has certain well-defined transfer characteristics related to space and location relative to other crops, and these help determine the rate at which individual fields become “contaminated” by the GM crop. We find that in many cases, careful attention needs to be paid to the spatial arrangement of GM crops in relation to non-GM crops in order to ensure that GM contamination is not ubiquitous. The relative ease of system-wide cross-pollination of farmland by GM crops indicates that significant external costs could be imposed on a typical farmer because of the inability to certify produce for sale in potentially lucrative GM-free markets. The analysis suggests that the potential for market failure in this industry may justify a need for government action, and that innovative and flexible regulatory structures will be needed to handle the wide range of co-mingling risks posed by differing crops.

Employing a composite gene-flow index to numerically quantify a crop’s potential for gene flow: an Irish perspective

Guidelines to ensure the efficient coexistence of genetically modified (GM) and conventional crops are currently being considered across the European Union. The purpose of this strategy is to describe the measures a farmer must adopt to minimize the admixture of GM and non-GM crops. Minimizing pollen/seed-mediated gene flow between GM and non-GM crops is central to successful coexistence. However no system is currently available to permit the numeric quantification of a crop's propensity for pollen/seed-mediated gene flow. The provision of such a system could permit a background level of gene flow, specific for a particular conventional crop, to be calculated. Here we present a gene flow index model implemented using the principal arable crops in Ireland as a model dataset. The objective of this research was to establish a baseline gene flow data set for Ireland's primary conventional crops through the provision of a simple numerical index. This Gene Flow Index (GFI) incorporates four strands of crop-mediated gene flow (crop pollen-to-crop, crop pollen-to-wild, crop seed-to-volunteer and crop seed-to-feral) into a format that permits the calculation of a crop's gene flow potential. Responsive to regional parameters, we have applied the model to sugar beet, oilseed rape, potato, ryegrass, maize, wheat and barley. We propose that the attained indices will highlight those crops that require additional measures in order to minimize gene flow in accordance with anticipated coexistence guidelines.

Orientation, Feeding, and Ovipositional Behavior of Diamondback Moth,Plutella xylostella(Lepidoptera: Plutellidae), on Transgenic Cabbage Expressing Cry1Ab Toxin ofBacillus thuringiensis(Berliner)

In the past few years, a number of transgenic plants expressing Bacillus thuringiensis (Bt) proteins have been commercialized throughout the world, particularly in the developed countries. In developing countries, the process of commercializing insect-resistant transgenic crops has begun and is likely to gain momentum in the near future. Resource-poor farmers who are unable to afford the cost of genetically modified (GM) seed fear that the pests will avoid GM fields and instead attack their non-GM fields. A study was conducted in India to elucidate whether pests will avoid the transgenic Bt crop and congregate in the fields with non-GM crops. Transgenic Bt cabbage and nontransgenic cabbage were compared for their suitability for oviposition, larval feeding, and orientation by the diamondback moth, Plutella xylostella, in the laboratory. Data presented in this study show that adult P. xylostella were equally attracted to transgenic and nontransgenic cabbage plants. Larval attraction to both types of plants was also equally high. After hatching on the transgenic cabbage plants, first instar larvae suffered 100% mortality and, therefore, did not move to nearby nontransgenic plants. However, the larvae released on the nontransgenic plant were attracted to transgenic plant placed in its vicinity and suffered heavy mortality.