Genetically modified crops: success, safety assessment, and public concern

With the emergence of transgenic technologies, new ways to improve the agronomic performance of crops for food, feed, and processing applications have been devised. In addition, ability to express foreign genes using transgenic technologies has opened up options for producing large quantities of commercially important industrial or pharmaceutical products in plants. Despite this high adoption rate and future promises, there is a multitude of concerns about the impact of genetically modified (GM) crops on the environment. Potential contamination of the environment and food chains has prompted detailed consideration of how such crops and the molecules that they produce can be effectively isolated and contained. One of the reasonable steps after creating a transgenic plant is to evaluate its potential benefits and risks to the environment and these should be compared to those generated by traditional agricultural practices. The precautionary approach in risk management of GM plants may make it necessary to monitor significant wild and weed populations that might be affected by transgene escape. Effective risk assessment and monitoring mechanisms are the basic prerequisites of any legal framework to adequately address the risks and watch out for new risks. Several agencies in different countries monitor the release of GM organisms or frame guidelines for the appropriate application of recombinant organisms in agro-industries so as to assure the safe use of recombinant organisms and to achieve sound overall development. We feel that it is important to establish an internationally harmonized framework for the safe handling of recombinant DNA organisms within a few years.This is IMTECH Communication No. 038/2005.     

转基因耐除草剂作物的环境风险及管理

自1996年第1例转基因作物在美国商业化种植, 其在全球的种植面积一直处于持续、快速增长的趋势。2010年, 全球转基因作物种植总面积达1.48×10⁸ hm², 所种植的转基因作物主要是耐除草剂和抗虫作物, 其中耐除草剂作物占种植总面积的81%。耐除草剂作物的种植为杂草的高效控制提供了新的手段, 但其可能带来的生态环境风险也引起了全世界各国的广泛关注和争议。该文在总结归纳前人研究的基础上, 针对耐除草剂作物的基因漂移、杂草化及对生物多样性的影响等当前人们普遍关注的环境风险问题, 系统讨论了相关的风险评价程序和方法, 概括和分析了当前耐除草剂作物的环境风险研究进展和管理措施, 以期为我国转基因耐除草剂作物的开发、风险评价及管理提供依据。     

Transgenic plants and biosafety: science, misconceptions and public perceptions

One usually thinks of plant biology as a non-controversial topic, but the concerns raised over the biosafety of genetically modified (GM) plants have reached disproportionate levels relative to the actual risks. While the technology of changing the genome of plants has been gradually refined and increasingly implemented, the commercialization of GM crops has exploded. Today's commercialized transgenic plants have been produced using Agrobacterium tumefaciens-mediated transformation or gene gun-mediated transformation. Recently, incremental improvements of biotechnologies, such as the use of green fluorescent protein (GFP) as a selectable marker, have been developed. Non-transformation genetic modification technologies such as chimeraplasty will be increasingly used to more precisely modify germplasm. In spite of the increasing knowledge about genetic modification of plants, concerns over ecological and food biosafety have escalated beyond scientific rationality. While several risks associated with GM crops and foods have been identified, the popular press, spurred by colorful protest groups, has left the general public with a sense of imminent danger. Reviewed here are the risks that are currently under research. Ecological biosafety research has identified potential risks associated with certain crop/transgene combinations, such as intra- and interspecific transgene flow, persistence and the consequences of transgenes in unintended hosts. Resistance management strategies for insect resistance transgenes and non-target effects of these genes have also been studied. Food biosafety research has focused on transgenic product toxicity and allergenicity. However, an estimated 3.5 x 10(12) transgenic plants have been grown in the U.S. in the past 12 years, with over two trillion being grown in 1999 and 2000 alone. These large numbers and the absence of any negative reports of compromised biosafety indicate that genetic modification by biotechnology poses no immediate or significant risks and that resulting food products from GM crops are as safe as foods from conventional varieties. We are increasingly convinced that scientists have a duty to conduct objective research and to effectively communicate the results--especially those pertaining to the relative risks and potential benefits--to scientists first and then to the public. All stakeholders in the technology need more effective dialogues to better understand risks and benefits of adopting or not adopting agricultural biotechnologies.     

转基因植物环境监测进展

近20年来,转基因植物的商业化应用规模越来越大,而转基因生物安全问题依然是转基因植物产业进一步发展的最主要制约因素。转基因植物在商业化应用之前虽然预先进行了风险评估,但是,包括环境监测在内的风险管理措施是确保转基因植物安全应用的必要手段。在转基因作物大规模应用近20年之后,其在靶标生物抗性、对生物多样性的影响、基因漂移、在生态系统中的长期存留等方面产生的环境风险已经渐渐显现出来,表明风险评估无法为转基因植物应用提供足够的安全保障,还必须通过开展系统而长期的环境监测,明确转基因植物在生产应用后的实际环境影响。联合国环境规划署和欧盟等已经制定了转基因植物环境监测的法规和技术指南,一些国家实施了系统的转基因植物环境监测。对转基因植物所产生的环境风险以及环境监测应包括的内容进行了综述。     

Biosafety management and commercial use of genetically modified crops in China

As a developing country with relatively limited arable land, China is making great efforts for development and use of genetically modified (GM) crops to boost agricultural productivity. Many GM crop varieties have been developed in China in recent years; in particular, China is playing a leading role in development of insect-resistant GM rice lines. To ensure the safe use of GM crops, biosafety risk assessments are required as an important part of the regulatory oversight of such products. With over 20 years of nationwide promotion of agricultural biotechnology, a relatively well-developed regulatory system for risk assessment and management of GM plants has been developed that establishes a firm basis for safe use of GM crops. So far, a total of seven GM crops involving ten events have been approved for commercial planting, and 5 GM crops with a total of 37 events have been approved for import as processing material in China. However, currently only insect-resistant Bt cotton and disease-resistant papaya have been commercially planted on a large scale. The planting of Bt cotton and disease-resistant papaya have provided efficient protection against cotton bollworms and Papaya ringspot virus (PRSV), respectively. As a consequence, chemical application to these crops has been significantly reduced, enhancing farm income while reducing human and non-target organism exposure to toxic chemicals. This article provides useful information for the colleagues, in particular for them whose mother tongue is not Chinese, to clearly understand the biosafety regulation and commercial use of genetically modified crops in China.     

The ecological risks of transgenic plants.

Biotechnologies have been utilized "ante litteram" for thousands of years to produce food and drink and genetic engineering techniques have been widely applied to produce many compounds for human use, from insulin to other medicines. The debate on genetically modified (GM) organisms broke out all over the world only when GM crops were released into the field. Plant ecologists, microbiologists and population geneticists carried out experiments aimed at evaluating the environmental impact of GM crops. The most significant findings concern: the spread of transgenes through GM pollen diffusion and its environmental impact after hybridisation with closely related wild species or subspecies; horizontal gene transfer from transgenic plants to soil microbes; the impact of insecticide proteins released into the soil by transformed plants on non-target microbial soil communities. Recent developments in genetic engineering produced a technology, dubbed "Terminator", which protects patented genes introduced in transgenic plants by killing the seeds in the second generation. This genetic construct, which interferes so heavily with fundamental life processes, is considered dangerous and should be ex-ante evaluated taking into account the data on "unexpected events", as here discussed, instead of relying on the "safe until proven otherwise" claim. Awareness that scientists, biotechnologists and genetic engineers cannot answer the fundamental question "how likely is that transgenes will be transferred from cultivated plants into the natural environment?" should foster long-term studies on the ecological risks and benefits of transgenic crops.     

Field trials and tribulations--making sense of the regulations for experimental field trials of transgenic crops in Europe

Transgenic plants that are being developed for commercial cultivation must be tested under field conditions to monitor their effects on surrounding wildlife and conventional crops. Developers also use this opportunity to evaluate the performance of transgenic crops in a typical environment, although this is a matter of commercial necessity rather than regulatory compliance. Most countries have adapted existing regulations or developed new ones to deal specifically with transgenic crops and their commodities. The European Union (EU) is renowned, or perhaps notorious, for having the broadest and most stringent regulations governing such field trials in the world. This reflects its nominal adherence to the precautionary approach, which assumes all transgenic crops carry an inherent risk. Therefore, field trials in the EU need to demonstrate that the risk associated with deploying a transgenic crop has been reduced to the level where it is regarded as acceptable within the narrowly defined limits of the regulations developed and enforced (albeit inconsistently) by national and regional governments, that is, that there is no greater risk than growing an equivalent conventional crop. The involvement of national and regional competent authorities in the decision-making process can add multiple layers of bureaucracy to an already-intricate process. In this review, we use country-based case studies to show how the EU, national and regional regulations are implemented, and we propose strategies that could increase the efficiency of regulation without burdening developers with further unnecessary bureaucracy.     

Environmental risk assessment of transgenic miraculin-accumulating tomato in a confined field trial in Japan

The commercial use of genetically modified (GM) crops requires prior assessment of the risks to the environment when these crops are grown in the field or distributed. Assessments protocols vary across countries and GM crop events, but there is a common need to assess environmental biosafety. In this study, we conducted an environmental risk assessment in a confined field of GM tomato plants that can produce miraculin, a taste-altering protein that causes sour tastes to be perceived as sweet, for practical use in Japan. The evaluation was conducted for 1) competitiveness (the ability to compete with wild plants for nutrients, sunlight, and growing areas and prevent their growth) and 2) the production of toxic substances (the ability to produce substances that interfere with the habitat and growth of wild plants, animals, and microorganisms). Investigations of plant morphology and growth characteristics as well as tolerance to low temperature during early growth and overwintering for assessment endpoints related to competitiveness showed no biologically meaningful difference between GM tomato and non-GM tomato. In addition, harmful substances in plant residues and root secretions were assessed by the plow-in method, succeeding crop test and soil microflora tests, and it was determined that GM tomato does not exhibit an increase in harmful substances. Based on these results, it was concluded that GM miraculin-accumulating tomato is comparable to conventional tomato and is unlikely to have unintended adverse effects in the natural environment of Japan.     

Genetically modified organisms and risks of their introduction

The major goal of this review is to assess food risks of the introduction of genetically modified (GM) crops. The author analyzes the properties of the several classes of target proteins used in the transgenic constructions and discusses the problems that arise due to the pleiotropic action of transgenic proteins, the horizontal transfer of the transgenic constructions, primarily in bacteria, and their instability. Particular consideration is given to elevated risks of using the GM plant varieties for producing pharmaceutical preparations, due to the probability of uncontrolled cross-pollination between the GM plants and the plants grown for foodstuff production. The author emphasizes the requirement for assessing in detail all hypothetic risks in each particular case of cultivating GM varieties; as a control, such assessment must involve a comprehensive comparison with the conventional parental forms.Translated from Fiziologiya Rastenii, Vol. 52, No. 1, 2005, pp. 115–128.Original Russian Text Copyright © 2005 by Kulikov.     

The development and status of Bt rice in China

Multiple lines of transgenic rice expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China, posing the prospect of increases in production with decreased application of pesticides. We explore the issues facing adoption of Bt rice for commercial production in China. A body of safety assessment work on Bt rice has shown that Bt rice poses a negligible risk to the environment and that Bt rice products are as safe as non‐Bt control rice products as food. China has a relatively well‐developed regulatory system for risk assessment and management of genetically modified (GM) plants; however, decision‐making regarding approval of commercial production has become politicized, and two Bt rice lines that otherwise were ready have not been allowed to enter the Chinese agricultural system. We predict that Chinese farmers would value the prospect of increased yield with decreased use of pesticide and would readily adopt production of Bt rice. That Bt rice lines may not be commercialized in the near future we attribute to social pressures, largely due to the low level of understanding and acceptance of GM crops by Chinese consumers. Hence, enhancing communication of GM crop science‐related issues to the public is an important, unmet need. While the dynamics of each issue are particular to China, they typify those in many countries where adoption of GM crops has been not been rapid; hence, the assessment of these dynamics might inform resolution of these issues in other countries.     

提高转基因作物生物安全性的分子策略

随着各类转基因作物的问世及其农产品的不断上市,转基因作物的安全性问题已成为公众关心的焦点。综述了提高转基因作物生物安全性的几种分子策略,其中包括选择标记的去除,转基因的组织特异表达和诱导性表达以及转基因逃逸的控制等。     

Advancing environmental risk assessment for transgenic biofeedstock crops

Transgenic modification of plants is a key enabling technology for developing sustainable biofeedstocks for biofuels production. Regulatory decisions and the wider acceptance and development of transgenic biofeedstock crops are considered from the context of science-based risk assessment. The risk assessment paradigm for transgenic biofeedstock crops is fundamentally no different from that of current generation transgenic crops, except that the focus of the assessment must consider the unique attributes of a given biofeedstock crop and its environmental release. For currently envisioned biofeedstock crops, particular emphasis in risk assessment will be given to characterization of altered metabolic profiles and their implications relative to non-target environmental effects and food safety; weediness and invasiveness when plants are modified for abiotic stress tolerance or are domesticated; and aggregate risk when plants are platforms for multi-product production. Robust risk assessments for transgenic biofeedstock crops are case-specific, initiated through problem formulation, and use tiered approaches for risk characterization.     

Environmental release of living modified organisms: current approaches and case studies

Agricultural biotechnology is being rapidly adopted as evidenced by the acreage of genetically modified (GM) crops planted and tonnes of product (grain and fiber) harvested. Concurrent with this technological progress, is a growing concern that the worlds biological diversity is coming under increasing threat from human activities. As such, ecological risk assessment approaches are being developed for GM crop plants as international agreements regulating the transboundary movements of these products are being implemented. This paper reviews the ecological risk assessment approach that has been used to date to approve GM crops to date. The process has been case-by-case, using a comparative, science-based approach balancing the potential risks and benefits of the new technology versus those present with the currently accepted practices. The approach used to evaluate and approve these products is consistent with the conditions and requirements outlined in the Cartagena Protocol.     

Suitability of non-lethal marker and marker-free systems for development of transgenic crop plants: present status and future prospects

Genetically modified crops are one of the prudent options for enhancing the production and productivity of crop plants by safeguarding from the losses due to biotic and abiotic stresses. Agrobacterium-mediated and biolistic transformation methods are used to develop transgenic crop plants in which selectable marker genes (SMG) are generally deployed to identify 'true' transformants. The commonly used SMG obtained from prokaryotic sources when employed in transgenic plants pose risks due to their lethal nature during selection process. In the recent past, some non-lethal SMGs have been identified and used for selection of transformants with increased precision and high selection efficiency. Considering the concerns related to bio-safety of the environment, it is desirable to remove the SMG in order to maximize the commercial success through wide adoption and public acceptance of genetically modified (GM) food crops. In this review, we examine the availability, and the suitability of wide range of non-lethal selection markers and elimination of SMG methods to develop marker-free transgenics for achieving global food security. As the strategies for marker-free plants are still in proof-of-concept stage, adaptation of new genomics tools for identification of novel non-lethal marker systems and its application for developing marker-free transgenics would further strengthen the crop improvement program.     

Assessing environmental risks of transgenic plants

By the end of the 1980s, a broad consensus had developed that there were potential environmental risks of transgenic plants requiring assessment and that this assessment must be done on a case-by-case basis, taking into account the transgene, recipient organism, intended environment of release, and the frequency and scale of the intended introduction. Since 1990, there have been gradual but substantial changes in the environmental risk assessment process. In this review, we focus on changes in the assessment of risks associated with non-target species and biodiversity, gene flow, and the evolution of resistance. Non-target risk assessment now focuses on risks of transgenic plants to the intended local environment of release. Measurements of gene flow indicate that it occurs at higher rates than believed in the early 1990s, mathematical theory is beginning to clarify expectations of risks associated with gene flow, and management methods are being developed to reduce gene flow and possibly mitigate its effects. Insect pest resistance risks are now managed using a high-dose/refuge or a refuge-only strategy, and the present research focuses on monitoring for resistance and encouraging compliance to requirements. We synthesize previous models for tiering risk assessment and propose a general model for tiering. Future transgenic crops are likely to pose greater challenges for risk assessment, and meeting these challenges will be crucial in developing a scientifically coherent risk assessment framework. Scientific understanding of the factors affecting environmental risk is still nascent, and environmental scientists need to help improve environmental risk assessment.     

REVIEW ARTICLE: Transgenic plants and the environment

With a continued increase in the range of transgenes, and plantspecies for which genetic modification is possible, this reviewattempts to bring together some of the factors that will influencethe eventual fate of transgenes in the environment, and theeffects that such a dispersal may have. The review is developedfrom papers presented at the SEB Swansea meeting (April, 1994). Using experiments with GM (genetically modified) plants, andmarkers in non-GM plants, as well as observations on naturaland crop populations, it is possible to predict isolation distancesrequired for limiting the unintentional release from GM crops,and the probable fate of both GM pollen and seed if it is releasedbeyond the GM plot. Knowledge of wild relatives of crop plants,and ecological mechanisms can also give insights into the possibleeffects of different transgenes on native plants, and otheragricultural crops. A large number of limited scale releasesof GM plants have now taken place from which we can gain informationon the performance of GM crops in an agricultural environment,and the stability of the GM phenotype. All this information,can help to form a sound basis for regulations on the releaseof GM plants, an assessment of the need for, and scope of monitoring,and the best way in which to use GM crops. Key words: Transgenic releases, genetically-modified plants, molecular ecology, transgene stability     

转基因抗虫作物对非靶标昆虫的影响

转基因抗虫作物自 1996年被批准商业化种植以来 ,它的抗虫性和经济效益已得到了普遍肯定 ,同时 ,转基因抗虫作物对非靶标生物的影响 ,如转基因抗虫作物的长期种植 ,是否会导致次要害虫上升为主要害虫 ,是否会影响有益昆虫 ,包括重要经济昆虫、捕食性和寄生性天敌以及重要蝶类的种类及种群数量 ,已成为转基因抗虫作物生态风险评估的重要内容。一些研究结果表明 ,转基因抗虫作物在对靶标害虫有效控制的同时 ,一些对杀虫蛋白不敏感的非靶标害虫有加重危害的趋势 ,由于种植转基因抗虫作物 ,减少了化学农药的使用 ,客观上也使非靶标害虫种群数量上升 ,这对转基因抗虫作物害虫综合治理提出了新的要求。靶标害虫数量的减少直接影响了害虫天敌种群数量 ,靶标害虫取食转基因抗虫作物后发育迟缓 ,也间接影响了天敌昆虫的生长发育 ,转基因抗虫作物的花粉或花蜜是一些重要经济昆虫如蜜蜂、熊蜂和一些寄生蜂 ,甚至捕食性天敌的食物来源 ,或花粉飘落到一些鳞翅目昆虫如家蚕或重要蝶类昆虫的寄主植物上 ,直接或间接对这些昆虫造成一定影响。目前大多数研究表明转基因抗虫作物对非靶标昆虫 ,特别是对有益昆虫没有明显的不利影响 ,也有研究报道认为对某些有益昆虫有一定的不良影响。这为深入开展转基因抗虫作物的生态安全     

Gene Flow,Risk Assessment and the Environmental Release of Transgenic Plants

The release of genetically modified plants is governed by regulations that aim to provide an assessment of potential impact on the environment. One of the most important components of this risk assessment is an evaluation of the probability of gene flow. In this review, we provide an overview of the current literature on gene flow from transgenic plants, providing a framework of issues for those considering the release of a transgenic plant into the environment. For some plants gene flow from transgenic crops is well documented, and this information is discussed in detail in this review. Mechanisms of gene flow vary from plant species to plant species and range from the possibility of asexual propagation, short- or long-distance pollen dispersal mediated by insects or wind and seed dispersal. Volunteer populations of transgenic plants may occur where seed is inadvertently spread during harvest or commercial distribution. If there are wild populations related to the transgenic crop then hybridization and eventually introgression in the wild may occur, as it has for herbicide resistant transgenic oilseed rape (Brassica napus). Tools to measure the amount of gene flow, experimental data measuring the distance of pollen dispersal, and experiments measuring hybridization and seed survivability are discussed in this review. The various methods that have been proposed to prevent gene flow from genetically modified plants are also described. The current “transgenic traits” in the major crops confer resistance to herbicides and certain insects. Such traits could confer a selective advantage (an increase in fitness) in wild plant populations in some circumstances, were gene flow to occur. However, there is ample evidence that gene flow from crops to related wild species occurred before the development of transgenic crops and this should be taken into account in the risk assessment process.     

Genetically modified soybeans and food allergies

Allergenic reactions to proteins expressed in GM crops has been one of the prominent concerns among biotechnology critics and a concern of regulatory agencies. Soybeans like many plants have intrinsic allergens that present problems for sensitive people. Current GM crops, including soybean, have not been shown to add any additional allergenic risk beyond the intrinsic risks already present. Biotechnology can be used to characterize and eliminate allergens naturally present in crops. Biotechnology has been used to remove a major allergen in soybean demonstrating that genetic modification can be used to reduce allergenicity of food and feed. This provides a model for further use of GM approaches to eliminate allergens.     

Capitalizing on deliberate, accidental, and GM-driven environmental change caused by crop modification

The transgenic traits associated with the majority of commercial genetically modified crops are focused on improving herbicide and insecticide management practices. The use of the transgenic technology in these crops and the associated chemistry has been the basis of studies that provide evidence for occasional improvement in environmental benefits due to the use of less residual herbicides, more targeted pesticides, and reduced field traffic. This is nicely exemplified through studies using Environmental Impact Quotient (EIQ) assessments. Whilst EIQ evaluations may sometimes illustrate environmental benefits they have their limitations. EIQ evaluations are not a surrogate for Environmental Risk Assessments and may not reflect real environmental interactions between crops and the environment. Addressing the impact cultivated plants have on the environment generally attracts little public attention and research funding, but the introduction of GM has facilitated an expansion of research to address potential environmental concerns from government, NGOs, industry, consumers, and growers. In this commentary, some evidence from our own research and several key papers that highlight EIQ assessments of the impact crops are having on the environment are presented. This information may be useful as an education tool on the potential benefits of GM and conventional farming. In addition, other deliberate, accidental, and GM-driven benefits derived from the examination of GM cropping systems is briefly discussed.