转基因抗除草剂油菜对近缘作物的基因漂移

以转基因抗除草剂油菜 Q3和 HCN- 19为花粉供体材料 ,油菜近缘作物为花粉受体材料 ,在自然授粉条件下研究甘蓝型油菜与芸薹属近缘作物间的基因漂移频率。结果表明 ,油菜对芸薹属 6个种甘蓝、黑芥、埃芥、芥菜型油菜、白菜型油菜和甘蓝型油菜的基因漂移率分别为 0、0 .0 2 4 %～ 0 .2 4 3%、 0 .0 2 8%～ 0 .0 92 %、 0 .10 9%～ 0 .95 1%、 0 .4 79%～ 0 .879%、 1.2 5 2 %～2 .191%。且基因漂移频率受多种因素影响 ,其中与杂交亲和性、花期同步率、种植面积等高度相关。通过花粉将抗除草剂基因漂移给近缘作物 ,油菜是需要特别关注的作物     

抗草丁膦和抗草甘膦转基因油菜的抗性基因向野芥菜的流动

通过人工去雄授粉和田间隔行种植试验,研究了抗草丁膦和抗草甘膦转基因油菜(Brassica napus)中的bar基因和EPSPS基因向野芥菜(B. juncea var. gracilis)流动的可能性。结果表明在人工授粉的情况下,以野芥菜为母本,分别以两种转基因油菜为父本,亲和性指数都很高,达13以上,与野芥菜自交或开放授粉条件下的亲和性指数没有明显差异,说明两种转基因油菜和野芥菜的亲和性较好。经两次除草剂筛选,人工杂交获得的所有F₁对相应的除草剂都表现出了明显的抗性,且经PCR检测扩增出了各自的特异性条带,说明人工杂交获得的所有F₁都携带了相应的抗性基因。F₁的适合度研究表明,两种F₁种子萌发率和母本都没有明显差异,营养生长明显好于母本。但花粉活力和结实率明显下降,携带抗草丁膦基因F₁的花粉活力和每角果粒数分别是32.4%和0.59粒,携带抗草甘膦基因F₁的花粉活力和每角果粒数分别是35.1%和0.58粒。经两次除草剂筛选和PCR检测,表明野芥菜和抗草丁膦油菜或与抗草甘膦油菜田间隔行种植分别能产生0.02%和0.014%的携带抗性基因的F₁杂种。以上结果表明抗除草剂转基因油菜的抗性基因具有向野芥菜流动的可能性,且bar和EPSPS基因向野芥菜流动的可能性类似,但对其可能引起的环境后果需要做进一步地深入研究。     

传粉导致的转基因白菜与其近缘种属材料间的基因流动

从形态、染色体及分子水平上证实,转基因不结球白菜(Brassica campestris ssp. chinensis var. utilis Tsen et Lee)中编码除草剂Basta抗性的bar基因能在田间条件下,经自然传粉,以较高频率侵入芜菁(B. campestris ssp. rapifera)、结球白菜(B. campestris ssp. pekinensis)和不结球白菜(B. campestris ssp. chinensis)的基因组中,也能少量侵入同属异种的甘蓝型油菜(B. napus)基因组中; 在温室人工辅助授粉条件下,除在上述种中的基因漂移率提高外,bar基因尚能以一定频率侵入同属的黑芥(B. nigra)、埃塞俄比亚芥(B. carinata)、芥菜(B. juncea)基因组中,但始终未能得到转基因白菜与结球甘蓝(B. oleracea)、萝卜(R. sativus)的杂种.转基因白菜与十字花科的7种常见杂草经温室人工辅助授粉,也均未得到抗性杂种.     

传粉导致的转基因白菜与其近缘种属材料间的基因流动

从形态、染色体及分子水平上证实,转基因不结球白菜(Brassica campestris ssp．chinensis var．utilis Tsen et Lee)中编码除草剂Basta抗性的bar基因能在田间条件下,经自然传粉,以较高频率侵入芜菁(B．campestris ssp．rapifera)、结球白菜(B．campestris／sssp．pek／nens／s)和不结球白菜(B．campestrs ssp．ch／nens／s)的基因组中,也能少量侵入同属异种的甘蓝型油菜(B.napus)基因组中;在温室人工辅助授粉条件下,除在上述种中的基因漂移率提高外,bar基因尚能以一定频率侵入同属的黑芥(B．nigra)、埃塞俄比亚芥(B．car／nata)、芥菜(B．juncea)基因组中,但始终未能得到转基因白菜与结球甘蓝(B．oleracea)、萝卜(尺．sativus)的杂种。转基因白菜与十字花科的7种常见杂草经温室人工辅助授粉,也均未得到抗性杂种。     

转基因玉米外源基因通过花粉漂移的频率和距离

基因漂移是转基因生物可能引起生态环境安全性问题的主要风险之一,选用美国孟山都公司的转基因抗除草剂玉米GA21进行了外源基因向周边环境遗传漂移的距离和频率的研究,结果表明:转基因玉米的外源基因可以向周边玉米品种进行漂移,其最大漂移频率为45.10%,150m处仍能检测到外源基因的漂移,防止转基因玉米基因向外扩散的最佳途径为设置隔离带,隔离距离以200m以上为好。     

油菜的遗传转化及抗溴苯腈转基因油菜的获得

以油菜(Brassica napus L.)的下胚轴和子叶为转化受体,建立了油菜的高效转化系统。在此基础上,将抗除草剂溴苯腈基因(bxn基因)导入油菜,获得了抗溴苯腈转基因油菜。分子检测实验证明,转基因油菜中含有bxn基因。转基因油菜可抗高达10~(-3)mol/L的溴苯腈。     

风向因素对转基因抗虫棉花基因漂移效率的影响

在转基因作物获准进行环境释放并实行大面积商品化推广的同时,基因漂移所引起的生态环境安全问题不容忽视。本研究以含有双价抗虫基因（Bt/CpTI）的转基因棉花SGK321为花粉供体材料,以常规非转基因棉花品种石远321、中棉35、吉扎1号为花粉受体材料,在温室中人工创造定向风和非定向风条件,应用PCR与蛋白检测相结合的方法,检测外源基因发生基因漂移的效率。结果表明：随着与转基因棉花SGK321距离的增加,外源基因转移至非转基因棉花的基因漂移频率呈现波动性变化。在定向风处理中,基因漂移频率在距离转基因棉花6.4 m处达到峰值33.33%,在测定范围内基因漂移最远距离为25.6 m;而在非定向风处理中,基因漂移频率在距离转基因棉花12.8 m处达到峰值36.67%,在测定范围内基因漂移最远距离为36 m。非定向风可显著提高转移至海岛棉吉扎1号的基因漂移频率。外源基因从SGK321转移至其非转基因亲本石远321的基因漂移频率显著高于转移至陆地棉中棉35和海岛棉吉扎1号的漂移频率。本研究可为转基因棉花的生态安全性分析提供一定的理论参考价值。     

转基因水稻外源基因的漂移研究

转基因水稻基因漂移可能带来环境安全性问题。利用农杆菌介导,把hpt基因转化水稻品种,通过后代筛选,以稳定遗传的含单拷贝转化株系为转基因花粉供体材料,研究转基因水稻向非转基因水稻不育系和常规稻(花粉受体)的外源基因漂移频率。结果表明,相邻种植时转基因水稻向雄性不育系品种的漂移频率为31.74%。随距离的增加漂移频率明显下降,在26m处仍能够检测到含外源基因个体的存在,并且在距离4m处出现一个漂移频率的升高;转基因水稻向常规品种的漂移频率则明显低于不育系,一般在2.0%以下,随距离的增加也呈现下降的趋势,在18m处开始无法检测到含外源基因的个体。     

转基因栽培稻基因漂移是否会带来环境生物安全影响?

转基因通过基因漂移可以渐渗到作物的野生近缘种,由此而导致的环境风险是全球广泛关注的生物安全问题.有3个关键因素可以决定环境风险的程度:特定空间距离的转基因漂移频率,转基因在野生近缘种中的表达水平,以及转基因为野生近缘种群体带来的适合度效应.本文将根据现有研究结果,从上述3方面对转基因漂移到非转基因栽培稻、杂草稻和野生稻造成的潜在环境影响进行回顾.栽培稻品种之间的基因漂移频率很低,可以通过空间隔离或其他方法使其降低到可忽略的水平.在共同分布的环境中,栽培稻基因(包括转基因)向杂草稻和野生稻的漂移不可避免.尽管抗虫转基因(Bt或Bt/CpTI)在栽培稻和野生近缘种杂交后代中可以正常表达,但由于在低虫压环境中,抗虫转基因不会明显改变野生近缘种的适合度,抗虫转基因漂移所造成的环境影响十分有限.因此对基因漂移而言,抗虫转基因栽培稻的商品化种植应该比较安全.然而,抗除草剂转基因渐渗到杂草稻或野生稻会改变群体的适合度,可能会引起不可预测的环境后果.     

风速对转基因棉花基因漂移的影响

在转基因作物全球商业化推广的20年间,公众对基因漂移生态安全问题的关注持续升温。本试验以转基因双价棉SGK321(Cry1Ac/Cp TI)为花粉供体,常规棉"石远321"和"中棉35"为花粉授体,借助PCR和蛋白检测技术,研究温室中3种风速(0.54、0.92和1.27 m·s-1)条件下的Cry1Ac基因漂移频率。结果表明:"石远321"作为花粉受体时,基因漂移频率受风速影响,低风速下最高,高风速下最低;"中棉35"作为花粉授体时,基因漂移频率整体较低,不受风速影响;基因漂移频率与所选择的花粉受体品种有关,"石远321"(转基因棉亲本)(10.63%)作为花粉受体时基因漂移频率高于"中棉35"(2.50%);转基因棉花基因漂移频率随着转基因作物种植区与非转基因作物之间距离的增加而下降。本试验为风介导的基因漂移的生态风险评估提供一定的理论参考。     

Gene flow from herbicide-tolerant GM rice and the heterosis of GM rice-weed F2 progeny

Gene flow from genetically modified (GM) crops to non-GM cultivars or weedy relatives may lead to the development of more aggressive weeds. We quantified the amount of gene flow from herbicide-tolerant GM rice (Protox GM, derived from the cultivar Dongjin) to three cultivars (Dongjin, Aranghyangchal and Hwaseong) and a weedy rice line. Gene flow frequency generally decreased with increasing distance from the pollen donor. At the shortest distance (0.5 m), we observed a maximum frequency (0.039%) of gene flow. We found that the cultivar Dongjin received the greatest amount of gene flow, with the second being weedy rice. Heterosis of F2 inbred progeny was also examined between Protox GM and weedy rice. We compared growth and reproduction between F2 progeny (homozygous or hemizygous for the Protox gene) and parental rice lines (GM and weedy rice). Here, transgene-homozygous F2 progeny was significantly taller and produced more seeds than the transgene-hemizygous F2 progeny and parental lines. Although the gene flow frequency was generally low, our results suggest that F2 progeny between GM and weedy relatives may exhibit heterosis.     

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。     

Two heteropteran predators in relation to weed management in herbicide-tolerant corn

Deployment of genetically modified (GM), herbicide-tolerant corn may alter weed flora abundance and composition and may affect pests and their natural enemies. Among on-plant predators, Orius spp. are the prevalent group in Spain and were selected to study the impact of glyphosate use on predators. We also studied Nabis sp. which is commonly recorded on corn in the study area. For this, a 4-year study was conducted in NE Spain. Three different herbicide regimes were compared: two glyphosate (a broad-spectrum herbicide) treatments per season, no herbicide treatment, and one pre-emergence conventional treatment with selective herbicides against broadleaf and grassy weeds. Density of main arthropod herbivores and the above two predatory groups was recorded on plants. Differences between herbicide regimes were observed in the two functional groups studied, herbivores and heteropteran predators. The comparison of glyphosate-treated and untreated plots showed significant differences for both functional groups, but the differences between glyphosate-treated and conventionally treated plots for the two functional groups were lower. For Orius spp., annual density per plot was significantly correlated with annual density of leafhoppers and to a lesser extent, with aphids. Nabis sp. densities were never different between glyphosate-treated and conventionally treated plots, and Nabis sp. density showed no relation to any of the herbivores tested. We concluded that no significant changes in heteropteran predator densities may be expected from moderate alterations in weeds arising from the deployment of herbicide-tolerant corn varieties and that leafhoppers are probably the herbivore prey that most influences Orius spp. densities in corn in our study area.     

Potential gene flow of two herbicide-tolerant transgenes from oilseed rape to wild B. juncea var. gracilis

Four successive reciprocal backcrosses between F₁ (obtained from wild Brassica juncea as maternal plants and transgenic glyphosate- or glufosinate-tolerant oilseed rape, B. napus, as paternal plants) or subsequent herbicide-tolerant backcross progenies and wild B. juncea were achieved by hand pollination to assess potential transgene flow. The third and forth reciprocal backcrosses produced a number of seeds per silique similar to that of self-pollinated wild B. juncea, except in plants with glufosinate-tolerant backcross progeny used as maternal plants and wild B. juncea as paternal plants, which produced fewer seeds per silique than did self-pollinated wild B. juncea. Germination percentages of reciprocal backcross progenies were high and equivalent to those of wild B. juncea. The herbicide-tolerant first reciprocal backcross progenies produced fewer siliques per plant than did wild B. juncea, but the herbicide-tolerant second or third reciprocal backcross progenies did not differ from the wild B. juncea in siliques per plant. The herbicide-tolerant second and third reciprocal backcross progenies produced an amount of seeds per silique similar to that of wild B. juncea except for with the glufosinate-tolerant first and second backcross progeny used as maternal plants and wild B. juncea as paternal plants. In the presence of herbicide selection pressure, inheritance of the glyphosate-tolerant transgene was stable across the second and third backcross generation, whereas the glufosinate-tolerant transgene was maintained, despite a lack of stabilized introgression. The occurrence of fertile, transgenic weed-like plants after only three crosses (F₁, first backcross, second backcross) suggests a potential rapid spread of transgenes from oilseed rape into its wild relative wild B. juncea. Transgene flow from glyphosate-tolerant oilseed rape might be easier than that from glufosinate-tolerant oilseed rape to wild B. juncea. The original insertion site of the transgene could affect introgression.     

转基因大豆豆粕外源基因和蛋白在SD大鼠体内消化吸收分析

为了评估转基因抗草甘膦除草剂大豆的食用安全性,以20%的比例将转基因抗草甘膦除草剂大豆GTS40-3-2和其亲本非转基因大豆A5403豆粕分别添加到基础饲料中喂养两代Sprague-Dawley(SD)大鼠,采用定性、定量PCR和ELISA方法检测转基因大豆成分相关基因和蛋白在长期饲喂的大鼠体内代谢残留状况。结果表明,大鼠喂养转基因大豆豆粕后,除了大鼠肠粪和盲肠内容物检测到有转基因成分的残留,肠道菌群和实质脏器均未发现相关基因和蛋白。结果提示,长期饲喂转基因抗草甘膦除草剂大豆GTS40-3-2与亲本A5403大豆豆粕对SD大鼠具有同样的食用安全性。     

Amelioration of biodiversity impacts of genetically modified crops: predicting transient versus long-term effects

It has been suggested that genetically modified herbicide-tolerant crops may benefit biodiversity because spraying of crops may be delayed until later in the growing season, allowing weeds to grow during the early part of the year. This provides an enhanced resource for arthropods, and potentially benefits birds that feed on these. Thus, this technology could enhance biodiversity. Using a review of weed phenologies and a population model, we show that many weeds are unlikely to benefit because spraying is generally delayed insufficiently late in the season to allow most to set seed. The positive effects on biodiversity observed in trials lasting one or two seasons are thus likely to be transient. For one weed of particular significance (Chenopodium album, fat hen) we show that it is unlikely that the positive effects observed could be maintained by inputs of seed during other parts of the rotation. However, we find preliminary evidence that if spraying can be ceased earlier in the season, then a viable population of late-emerging weeds could be maintained. This strategy could benefit weeds in both genetically modified (GM) and non-GM crops, but would probably lead to reduced inputs in GM systems compared with conventional ones.     

Simulated crop rotation systems control swede midge, Contarinia nasturtii

Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), a common insect pest in Europe and a new invasive pest in North America, causes severe damage to cruciferous crops. Many counties in Canada and the USA, in which C. nasturtii has not been previously reported, are at risk of being infested by C. nasturtii . Effectiveness of chemical control is limited, especially under high population pressure in fields. Alternative management strategies against C. nasturtii are sorely needed in order to protect crucifers. Under controlled laboratory conditions, the effectiveness on C. nasturtii control by 11 simulated cauliflower-sweet corn and cauliflower-kidney bean crop rotation systems was evaluated, with and without the presence of cruciferous weeds as alternative hosts. Our results indicated that when soil was infested with C. nasturtii pupae, the emergence pattern from the soil was very similar regardless whether the soil was later planted to host or non-host plants. As emergence was not affected, we examined whether manipulating host availability for oviposition through crop rotation would be effective. Our results indicated that the simulated cauliflower-sweet corn and cauliflower-kidney bean rotation systems provided full control of C. nasturtii . The effectiveness of one cycle of non-host crop rotation was reduced when cruciferous weeds were present. However, the C. nasturtii population in a one-cycle non-host rotation system with cruciferous weeds present was significantly lower than that in a non-rotation system. Two consecutive cycles (simulating a cropping season) of non-host plant crop rotations provided full control of C. nasturtii , regardless of the presence of the cruciferous weeds. The importance of cruciferous weed management and how to implement a successful crop rotation in fields to control C. nasturtii are discussed.     

转基因水稻外源基因向近缘种群漂流和渐渗的研究进展

水稻是我国最重要的粮食作物之一,我国有8亿以上的人口以稻米作为主食。但在水稻生产中,由于病、虫、草害及不良气候等逆境因子的影响,严重制约了水稻的高产、稳产。转基因生物技术的迅速发展,为水稻抗性育种提供了新途径。自20世纪80年代以来,我国全方位地开展了转基因水稻的研发,目前已经培育出大量的抗病、抗虫、抗除草剂和抗逆的转基因水稻品种,这将为提高我国水稻的生产力和确保粮食安全做出重要的贡献。但转基因水稻的基因漂流及其可能带来的生物安全问题备受关注。已有报道证明,外源转基因可以通过异交向非转基因品种和野生近缘种漂流。在不同的试验条件下,抗除草剂基因有0．05％-0．53％逃逸的可能,其向不育系的最大漂移频率可达4．518％。抗虫基因向相邻非转基因水稻的平均漂移频率最高为0．875％。因此,本文对水稻与其近缘野生种的杂交情况,转基因水稻外源基因向非转基因品种、野生近缘种以及野生非近缘种的漂流和渐渗及其潜在的生态环境风险等方面进行了简要分析,并对转基因水稻的发展进行了展望,以期为转基因水稻的安全应用提供参考。     

A study of crop-to-crop gene flow using farm scale sites of fodder maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) in the UK

From 2000 to 2003 a range of Farm Scale Evaluation (FSE) trials were established in the UK to assess the effect of the release and management of herbicide tolerant (HT) crops on arable weeds and invertebrates. The FSE trials for maize were also used to investigate crop-to-crop gene flow and to develop a statistical model for the prediction of gene flow frequency that can be used to evaluate current separation distance guidelines for GM crops. Seed samples were collected from the non-GM half of 55 trial sites and 1,055 were tested for evidence of gene flow from the GM HT halves using a quantitative PCR assay specific to the HT (pat) gene. Rates of gene flow were found to decrease rapidly with increasing distance from the GM source. Gene flow was detected in 30% of the samples (40 out of 135) at 150 m from the GM source and events of GM to non-GM gene flow were detected at distances up to and including 200 m from the GM source. The quantitative data were subjected to statistical analysis and a two-step model was found to provide the best fit for the data. A dynamic whole field model predicted that a square field (150 m x 150 m in size) of grain maize would require a separation distance of 3 m for the adjacent crop to be below a 0.9% threshold (with <2% probability of exceeding the threshold). The data and models presented here are discussed in the context of necessary separation distances to achieve various possible thresholds for adventitious presence of GM in maize.