PCR detection of genetically modified soya and maize in foodstuffs

The detection of genetically modified foodstuffs is becoming both a food sales and legal necessity. This study reports a rapid DNA extraction/PCR-based method for the detection of genetically modified soya (GMS) and maize (GMM) in mixed samples of transgenic and unmodified soybeans and maize kernels, and a variety of processed samples including soya flour, soya protein isolates, extruded defatted soya, acid- and alcohol-precipitated soya concentrates, soya lecithin, maize grits, seasoned corn puffs and salted corn chips. The presence of GMS DNA was determined with two pairs of primers directed towards different GMS target sequences and GMM by one primer pair. In addition, a multiplex PCR reaction which utilises an internal positive control was developed for both genetically modified organisms (GMOs). Results indicated that the methods are sensitive and specific enough to detect GMS down to a level of 0.01% dry weight in single-product PCRs and 0.1% in multiplex PCRs and GMM down to 0.001% dry weight in single-product PCRs and 0.01% in multiplex PCR. The methods are considered to represent a viable route for the commercial detection of GMS and GMM in foodstuffs.     

Stable transformation of the cotton plastid genome and maternal inheritance of transgenes

Chloroplast genetic engineering overcomes concerns of gene containment, low levels of transgene expression, gene silencing, positional and pleiotropic effects or presence of vector sequences in transformed genomes. Several therapeutic proteins and agronomic traits have been highly expressed via the tobacco chloroplast genome but extending this concept to important crops has been a major challenge; lack of 100 homologous species-specific chloroplast transformation vectors containing suitable selectable markers, ability to regulate transgene expression in developing plastids and inadequate tissue culture systems via somatic embryogenesis are major challenges. We employed a Double Gene/Single Selection (DGSS) plastid transformation vector that harbors two selectable marker genes (aphA-6 and nptII) to detoxify the same antibiotic by two enzymes, irrespective of the type of tissues or plastids; by combining this with an efficient regeneration system via somatic embryogenesis, cotton plastid transformation was achieved for the first time. The DGSS transformation vector is at least 8-fold (1 event/2.4 bombarded plates) more efficient than Single Gene/Single Selection (SGSS) vector (aphA-6; 1 event per 20 bombarded plates). Chloroplast transgenic lines were fertile, flowered and set seeds similar to untransformed plants. Transgenes stably integrated into the cotton chloroplast genome were maternally inherited and were not transmitted via pollen when out-crossed with untransformed female plants. Cotton is one of the most important genetically modified crops ($ 120 billion US annual economy). Successful transformation of the chloroplast genome should address concerns about transgene escape, insects developing resistance, inadequate insect control and promote public acceptance of genetically modified cotton.     

转基因作物的安全性争论及其对策

本文介绍了最近国际上对转基因植物安全性的争论情况,争论的本质并不纯粹是科学问题,而是政治和贸易问题,作者认为中国作为发展中国家应有自己的观点,并提出了相应的对策建议。     

转基因作物与非转基因作物的共存立法动态研究——以美、日、欧应对基因污染事件为视角

随着基因工程技术的运用与发展,越来越多的转基因作物基因污染事件的发生也引起了世界各国对转基因作物与非转基因作物之间的和谐发展问题的高度重视。以美、日、欧为代表,世界各国对转基因作物与非转基因作物的共存问题都进行了积极地探索。借鉴美、日、欧转基因与非转基因作物共存法律制度,以期为我国转基因与非转基因作物共存法律制度的构建提供参考。     

Refuges in reverse: the spread of Bacillus thuringiensis resistance to unselected greenhouse populations of cabbage loopers Trichoplusia ni

1 The dispersal of susceptible insects between refuges and Bacillus thuringiensis (Bt) treated fields is the key to resistance management of Bt crops. Here we describe the opposite situation; the movement of Bt resistant Trichoplusia ni moths from over‐wintered, greenhouse populations in British Columbia (BC) exposed to high Bt use to neighbouring greenhouses where Bt sprays have not been used. 2 The spread of Bt resistance to non‐selected populations of T. ni, and the resulting increase in resistance, indicates a surprising level of dispersal of resistant moths among greenhouses even in the face of fitness costs. 3 Field populations of T. ni in BC are seasonal migrants from regions of California where Bt cotton is grown. In 2006, field populations surveyed along the migration path from California through Oregon were highly susceptible to Bt insecticides and, thus, showed no indication of selection for resistance among these source populations. 4 The arrival of the immigrant moths provides a potential source of susceptible individuals to dilute the levels of resistance in greenhouse populations in BC later in the summer, but this has not occurred. Thus, field populations in BC do not appear to serve as refuges to combat Bt resistance in greenhouse populations.     

转基因作物的食用与环境安全性问题及其对策

自转基因技术研发和商业化生产以来,针对转基因作物的食用安全性和环境安全性问题一直是公众争论的焦点。面对全球粮食安全形势的严峻压力,如何使公众对转基因技术及其产品的客观性保持一种科学性的认识,是摆在各国(特别是发展中国家)政府和科学家面前不可忽视的课题。本文从食品和环境两个方面简要介绍了转基因作物的安全性问题,旨在还原转基因技术的科学真实性,并简要提出转基因作物的安全性对策。     

转基因植物中外源基因及其表达产物转移的途径

随着转基因植物商品化应用的增多,全面了解转基因植物潜在的生态风险性尤为重要。国内外对“转基因植物中外源基因向野生亲缘物种漂移的可能性”、“昆虫对抗虫转基因植物的耐受性”以及“转基因植物对生物多样性的潜在影响”等问题已进行了广泛研究。对转基因植物中外源基因及其表达产物的几种可能转移途径作了概述。着重介绍了“经花粉散布或与野生亲缘物种杂交等途径引起的外源基因转移”以及“转基因植物对土壤生态系统的影响”等方面的研究情况。此外,还对“鉴定外源基因及其表达产物存在的方法”进行了简要探讨。     

Beyond the spore--past and future developments of Bacillus thuringiensis as a biopesticide

Formulated and sporulated cultures of Bacillus thuringiensis (Bt) are widely used as foliar sprays as part of integrated pest management strategies against insect pests of agricultural crops. Although in several cases the presence of the spore has been shown to improve the activity of the product, other Bt-based insecticides have been developed in which the spore is absent. The most notable of these are transgenic plants expressing just the insect toxin gene from the bacterium. This paper will discuss these developments, and the advantages and disadvantages of having the spore present.     

抗除草剂转基因水稻对二种刺吸性害虫和二种天敌的影响

为探明转基因抗除草剂水稻对非目标生物的影响,于2007年和2008年对转Bar基因抗除草剂籼稻Bar68-1和非转基因对照D68稻田的2种常见刺吸性害虫和2种天敌在水稻分蘖中期、分蘖末期、齐穗期和乳熟期4个时期的种群密度进行了调查和比较。结果显示,抗除草剂水稻与对照稻田的飞虱、叶蝉、盲蝽、蜘蛛的发生密度,除不喷药处理区的2007年水稻乳熟期和2008年分蘖中期的盲蝽科的发生密度差异显著外,其余均无显著差异。试验结果表明,转基因抗除草剂水稻Bar68-1对包括飞虱、叶蝉、盲蝽、蜘蛛等类群在内的稻田非目标生物的田间自然种群的影响与非转基因水稻基本相同。     

Genetically modified soybeans: false-positive detection in fermented natural soybean (tempe)

Tempe was prepared using mixtures of natural soybean and genetically modified Roundup Ready (RUR) soybean fermented with natural Rhizopus sp. The amount of RUR soybean was quantified using an ELISA plate test. The RUR signal decreased during fermentation. In the control experiments on fermentation of non-RUR soybean, the tempe gave a false-positive RUR signal. The cross-reacting substance was generated only in non-RUR soybean during fermentation by Rhizopus sp., Rhizopus oligosporus, R. oryzae, Mucor rouxii and Aspergillus awamori.     

转基因抗虫作物对捕食性瓢虫的安全性研究进展

转基因抗虫作物的商业化种植带来了显著的经济、生态和社会效益,对转基因抗虫作物的安全性评价也一直是国内外学者研究的热点。对生物非靶标效应的研究是转基因抗虫作物安全性评价的重要组成部分,农田天敌类生物是其中的重点内容之一。瓢虫是农田生态系统重要的捕食性天敌,评价其在转基因抗虫作物田间是否能通过捕食猎物或取食花粉而接触到杀虫蛋白并富集于体内,进而对自身产生一定的非靶标效应,这对捕食性瓢虫的安全性研究具有重要的意义。本文从捕食性天敌瓢虫的生命表参数、行为功能参数、田间群落参数及体内微环境指标等方面综述了转基因抗虫作物对瓢虫的安全性研究进展,并对后期转基因抗虫作物对田间捕食性天敌的研究方向提出了建议,以期为转基因抗虫作物的环境安全性研究提供理论指导和为进一步完善转基因抗虫作物对瓢虫安全性评价的技术体系提供系统的数据资料。     

转基因作物对土壤微生物群落影响的研究进展

转基因作物的安全是全球的热点问题之一。土壤微生物在土壤有机质转化、养分矿化、腐殖质形成和土壤结构改良等几个过程中发挥着重要作用。虽然转基因作物在提高农业生产方面具有巨大的潜力,但它们对土壤安全和土壤微生物的潜在影响还有待进一步的深入研究。本文综述了抗虫、抗病、抗除草剂等3类转基因作物对土壤微生物多样性和群落结构产生的影响,提出了转基因作物土壤生态安全评价中还应考虑的问题,并对今后的工作做了展望。     

Introduction of the rd29A:AtDREB2A CA gene into soybean (Glycine max L. Merril) and its molecular characterization in leaves and roots during dehydration

The loss of soybean yield to Brazilian producers because of a water deficit in the 2011–2012 season was 12.9%. To reduce such losses, molecular biology techniques, including plant transformation, can be used to insert genes of interest into conventional soybean cultivars to produce lines that are more tolerant to drought. The abscisic acid (ABA)-independent Dehydration Responsive Element Binding (DREB) gene family has been used to obtain plants with increased tolerance to abiotic stresses. In the present study, the rd29A:AtDREB2A CA gene from Arabidopsis thaliana was inserted into soybean using biolistics. Seventy-eight genetically modified (GM) soybean lines containing 2–17 copies of the AtDREB2A CA gene were produced. Two GM soybean lines (P1397 and P2193) were analyzed to assess the differential expression of the AtDREB2A CA transgene in leaves and roots submitted to various dehydration treatments. Both GM lines exhibited high expression of the transgene, with the roots of P2193 showing the highest expression levels during water deficit. Physiological parameters examined during water deficit confirmed the induction of stress. This analysis of AtDREB2A CA expression in GM soybean indicated that line P2193 had the greatest stability and highest expression in roots during water deficit-induced stress.     

Detection of airborne genetically modified maize pollen by real-time PCR

The cultivation of genetically modified (GM) crops has raised numerous concerns in the European Union and other parts of the world about their environmental and economic impact. Especially outcrossing of genetically modified organisms (GMO) was from the beginning a critical issue as airborne pollen has been considered an important way of GMO dispersal. Here, we investigate the use of airborne pollen sampling combined with microscopic analysis and molecular PCR analysis as an approach to monitor GM maize cultivations in a specific area. Field trial experiments in the European Union and South America demonstrated the applicability of the approach under different climate conditions, in rural and semi-urban environment, even at very low levels of airborne pollen. The study documents in detail the sampling of GM pollen, sample DNA extraction and real-time PCR analysis. Our results suggest that this 'GM pollen monitoring by bioaerosol sampling and PCR screening' approach might represent an useful aid in the surveillance of GM-free areas, centres of origin and natural reserves.     

Delaying evolution of insect resistance to transgenic crops by decreasing dominance and heritability

The refuge strategy is used widely for delaying evolution of insect resistance to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Farmers grow refuges of host plants that do not produce Bt toxins to promote survival of susceptible pests. Many modelling studies predict that refuges will delay resistance longest if alleles conferring resistance are rare, most resistant adults mate with susceptible adults, and Bt plants have sufficiently high toxin concentration to kill heterozygous progeny from such matings. In contrast, based on their model of the cotton pest Heliothis virescens, Vacher et al. (Journal of Evolutionary Biology, 16, 2003, 378) concluded that low rather than high toxin doses would delay resistance most effectively. We demonstrate here that their conclusion arises from invalid assumptions about larval concentration-mortality responses and dominance of resistance. Incorporation of bioassay data from H. virescens and another key cotton pest (Pectinophora gossypiella) into a population genetic model shows that toxin concentrations high enough to kill all or nearly all heterozygotes should delay resistance longer than lower concentrations.