转基因玉米育种研究进展

转基因性状包括抗虫、耐除草剂、耐干旱、雄性不育、高赖氨酸含量和耐热淀粉酶等。介绍了转基因玉米的转化途径、转基因玉米的功能基因及性状、转基因玉米的基因聚合方法以及目前美国市场上的主要转基因玉米性状、转基因玉米及其产品检测技术和转Bt基因玉米害虫的抗性治理,讨论转基因玉米基因专利失效以后的管理问题和转基因玉米基因发展趋势。     

转Bt基因棉与有机棉生产

有机棉生产的特点是完全不用化学品 ,包括杀虫剂、除草剂、生长调节剂、化肥等等 ,因此在害虫虫口压力较大的地区不适合种植有机棉。而在这些地区种植转基因抗虫棉从理论上说可以解决这个问题。目前的问题是 ,欧洲和美国的权威机构均未认可转基因棉是环境友好作物 ,因此尚不能认可其作为有机棉生产中的一环。现在的转基因棉抗虫的主要来源是自身产生毒素蛋白 ,但仅靠产生毒素蛋白抗虫却不是生物工程棉花的唯一途径。新的转基因棉花类型将包括彩色棉和特种纤维性状的生物工程转育 ,并且有可能争取在将来用于有机棉生产中转Bt基因棉与有机棉…     

转Bt基因抗虫玉米发展状况及对非靶标昆虫的影响

转Bt基因抗虫玉米是目前商品化进程最快的转基因作物之一,并被广泛应用于农业生产,其抗虫性和经济效益已得到普遍肯定,但外源基因的导入一定程度上改变了玉米自身的基因序列,因此转Bt基因抗虫玉米对生态安全的影响也备受关注.本文从转Bt基因抗虫玉米发展现状及对非靶标昆虫影响的角度对转Bt基因玉米的安全性研究加以综述.     

美国主要作物转基因商业化进展及启示

分析了美国玉米、大豆和棉花3种主要作物转基因品种的商业化进程,结果表明：玉米、大豆和棉花在美国已经基本实现了品种的转基因化,2010年已分别达到86%、93%和93%。无论是抗虫、还是抗除草剂、或者是既抗虫又抗除草剂的转基因品种,在美国都大受农场主的欢迎,这揭示转基因技术为农业生产者带来了巨大的利益。分析了我国转基因作物商业化现状,棉花、玉米、大豆都与美国有很大的差距,仅水稻的转基因研究领先于美国。因此,建议积极推进转基因水稻的商业化进程,保持水稻研究的先发优势,加强其他作物转基因研究,并适时商业化,保障我国的粮食安全。     

耐除草剂转基因玉米CM8401的获得及功能性状鉴定

耐草甘膦和耐草铵膦是转基因作物育种重要的目标性状。将耐草甘膦基因MC1-EPSPS构建到含有bar基因的植物表达载体pTF101.1中，通过农杆菌介导法转入玉米材料Hi-II中，从而获得兼具耐受草甘膦和草铵膦性状的转基因玉米材料 CM8401。目的基因PCR检测显示，MC1-EPSPS和bar基因稳定整合到玉米基因组中。目的蛋白试纸条检测结果显示，MC1-EPSPS蛋白和PAT蛋白在转基因玉米世代间中表达稳定。田间除草剂耐受性鉴定试验表明，转基因玉米CM8401对草甘膦和草铵膦都具有良好耐受性，可耐受4倍推荐中剂量的草甘膦和草铵膦。     

转基因技术在玉米遗传育种中的应用

世界上转基因玉米已占玉米种植面积的11%,17种转基因玉米被正式批准投入商品化。应用于玉米上的主要转基因技术有农杆菌介导法、基因枪法、花粉管通道法等。转基因玉米的主要类型有抗虫玉米、抗除草剂玉米、抗病玉米、高赖氨酸玉米和抗寒玉米等。转基因玉米将向特殊营养及饲料专用方向发展,以满足高附加值的市场需求。     

转基因棉花在生产应用上的风险与安全控制

针对转Bt基因抗虫棉在各棉区广泛种植的现状,分析了转外源基因棉花在生产应用上存在抗除草剂棉花可能成为杂草、基因漂移威胁棉花近缘物种、转基因棉加速害虫的抗性进化、对非靶标有益生物的影响、转基因棉花对土壤生态环境的影响等风险,提出培育种植转多基因棉花、调控外源基因表达、设置棉花害虫＂庇护所＂、轮换种植不同类型的转基因棉品种、建立转基因棉花害虫综合治理技术体系等转Bt基因抗虫棉的安全控制措施。     

转Bt基因抗虫玉米发展状况及对非靶标昆虫的影响

转Bt基因抗虫玉米是目前商品化进程最快的转基因作物之一,并被广泛应用于农业生产,其抗虫性和经济效益已得到普遍肯定,但外源基因的导入一定程度上改变了玉米自身的基因序列,因此转Bt基因抗虫玉米对生态安全的影响也备受关注。本文从转Bt基因抗虫玉米发展现状及对非靶标昆虫影响的角度对转Bt基因玉米的安全性研究加以综述。     

转基因抗虫棉研究进展、问题及对策

转基因抗虫棉研究最常用的外源基因有两种,即Bt基因和CPTI基因.这两种基因现已被分别或同时导入棉株中并得到高效表达、稳定遗传的转基因棉花品种(系).目前世界各主产棉国均有不同面积种植.转基因抗虫棉存在的主要问题是抗虫持久性、抗虫的时空性、抗虫范围狭窄及抗虫棉的安全管理.解决这些问题的方法主要有寻找和构建特异高效表达起动子;筛选广谱高效抗虫基因;培育转多基因抗虫棉以及加强抗虫棉的区域种植管理和安全评价研究.     

中国转基因抗虫棉的发展和应用

从 2 0世纪 90年代起 ,中国开始了转基因抗虫棉的研究、开发和利用。转基因抗虫棉最常用的外源基因是 Bt基因和 Cp TI基因。这两种基因已被分别或同时导入棉株中并获得了一批有发展前景的转基因棉花品种。中国转基因棉花品种种植面积占棉花总面积的比例 2 0 0 0年到达 30 %。目前在我国所推广的抗虫棉 ,存在的主要问题是抗虫的时空性、害虫抗性、抗虫范围狭窄、抗虫强度差及抗虫棉的安全管理。解决这些问题的方法主要有寻找和筛选广谱抗虫基因 ,采用特异启动子和诱导表达启动子 ,培育转多基因抗虫棉 ,加强转基因抗虫棉的种植管理及安全性评价研究。     

Current and Potential Role of Transgenic Crops in U.S. Agriculture

SUMMARY

Transgenic crop cultivars with resistance to insects, pathogens, and herbicides offer growers powerful new pest management tools. We reviewed the observed and potential farm-level impacts of transgenic cultivars, including those with regulatory approval and commercial availability as well as those still being researched and developed. Direct grower benefits, such as yield and production increases and decreased management costs, have led to rapid and extensive adoption of Bt corn and cotton, herbicide-resistant cotton, soybean, and canola, and virus-resistant papaya. Other transgenic crops, including Bt sweet corn and potato, and herbicide-resistant sugar beet and corn, have not been adopted despite strong agronomic and pest management performance, largely because growers fear there will be no market for their harvests. Despite inconsistent adoption of transgenic cultivars, demonstrated benefits of the technology encourage ongoing efforts to incorporate pest management traits into a wider variety of crops, including broccoli, tomato, lettuce, grape, citrus, pineapple, raspberry, peanut, wheat, barley, and rice. Potential impacts of these upcoming transgenic cultivars range from a decrease in weed management costs for lettuce and tomato growers, to the defense of stone fruit, grape, and citrus against devastating new pests.     

转基因玉米SW12-859的抗螟性及农艺性状评价

SW12-859为吉林省农业科学院农业生物技术研究所培育的转基因玉米杂交组合,全株表达Cry1F基因杀虫蛋白。本研究以其为材料,与其遗传背景相似的郑单958为非转基因对照,在玉米心叶期(6~8叶期)和穗期(13~16叶期)进行田间人工接玉米螟初孵幼虫,调查其抗螟性、农艺性状及对产量损失的影响。结果表明,在玉米心叶期和穗期,转基因玉米SW12-859对一、二代玉米螟表现为高抗,郑单958表现为感,二者受玉米螟危害程度(抗螟性)差异显著。转基因玉米SW12-859和郑单958的株高、穗位高等农艺性状相近,在接虫条件下,转基因玉米产量显著高于非转基因玉米。     

Phase II-Inducing,Polyphenols Content and Antioxidant Capacity of Corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) from Phenotypes of White,Blue, Red and Purple Colors Processed into Masa and Tortillas

White, blue, red and purple corns (Zea mays L.) were lime-cooked to obtain masa for tortillas. The total phenolics and anthocyanins content, antioxidant activity expressed as total reducing power (TRP), peroxyl radical bleaching (PRAC), total antioxidant activity (TAA) and quinone reductase (QR) induction in the murine hepatoma (Hepa 1 c1c7 cell line) as a biological marker for phase II detoxification enzymes were investigated. Among the extracts prepared from raw corn varieties the highest concentration of total phenolics, anthocyanins, antioxidant index and induction of QR-inducing activity were found in the Veracruz 42 (Ver 42) genotype. The nixtamalization process (masa) reduced total phenolics, anthocyanins and antioxidant activities and the ability for QR induction when was compared to raw grain. Processing masa into tortillas also negatively affected total phenolics, anthocyanin concentration, antioxidant activities, and QR induction in the colored corn varieties. The blue variety and its corresponding masa and tortillas did not induce QR. Ver 42 genotype and their products (masa and tortilla) showed the greatest antioxidant activity and capacity to induce QR     

Meeting demands for increased cereal production in China

Meeting demands for increased cereal production in China is a great challenge and this paper provides updated information on cereal production and the potential adaptation of cropping systems to climate change, as well as on progress in improving yield potential and developing molecular markers and GM cereals in China. Maize production and soybean imports are increasing significantly to meet the strong demand for feed by a rapidly growing livestock industry. Extension of the rice and maize growing seasons in northeastern China and improvement of the cropping system through delayed wheat planting have contributed to improving cereal productivity despite changing climatic conditions. Significant improvements in yield potential of rice, maize, and wheat have been achieved. Comparative genomics has been successfully used to develop and validate functional markers for processing quality traits in wheat, and also for developing new varieties. Although transgenic Bt rice and maize, and maize expressing phytase have been developed, their commercialization has not been officially permitted. International collaboration has contributed significantly to cereal production by providing germplasm and improved crop management practices. Full integration of applied molecular technologies into conventional breeding programs and promotion of lower-input technologies, will play a key role in increasing and sustaining future cereal production.     

Do Sesamia nonagrioides (Lepidoptera; Noctuidae) Gravid Females Discriminate Between Bt or Multivitamin Corn Varieties? Role of Olfactory and Visual Cues

The Mediterranean corn borer, Sesamia nonagrioides Lefèbvre, is a key pest of corn and a main target of Bacillus thuringiensis (Bt) corn in Northeast Spain. Trends for future biotechnology crops indicate that Bt, non-Bt, and stacked corn varieties with metabolic pathways for vitamin-increased traits could coexist in same region. Knowledge of the oviposition response of gravid females of S. nonagrioides to these different varieties could be extremely important for managing strategies aimed for delaying resistance development. In dual-choice assays, we examined the host preference of gravid females of S. nonagrioides for four corn varieties: a new transgenic corn with increased vitamin levels, its near isogenic counterpart (M37W), a Bt corn plant, and its near isogenic counterpart. Olfactory cues were the predominant ones when gravid females looked for a suitable host to lay eggs, and no synergistic effects were observed when both visual and olfactory cues were present. When the plant was visible, the females preferred the odors emitted by the nontransgenic to its multivitamin transgenic counterpart and when they only could detect the volatiles they also preferred the nontransgenic M37W variety to the Bt corn variety. If gravid females are less attracted to corn with an increased level of vitamins, this could impact insect resistance management and the value of refuge plants, if such traits are stacked with an insect resistance trait.     

Societal Costs of Late Blight in Potato and Prospects of Durable Resistance Through Cisgenic Modification

In the European Union almost 6 Mha of potatoes are grown representing a value of close to €6,000,000,000. Late blight caused by Phytophthora infestans causes annual losses (costs of control and damage) estimated at more than €1,000,000,000. Chemical control is under pressure as late blight becomes increasingly aggressive and there is societal resistance against the use of environmentally unfriendly chemicals. Breeding programmes have not been able to markedly increase the level of resistance of current potato varieties. New scientific approaches may yield genetically modified marker-free potato varieties (either trans- and/or cisgenic, the latter signifying the use of indigenous resistance genes) as improved variants of currently used varieties showing far greater levels of resistance. There are strong scientific investments needed to develop such improved varieties but these varieties will have great economic and environmental impact. Here we present an approach, based on (cisgenic) resistance genes that will enhance the impact. It consists of five themes: the detection of R-genes in the wild potato gene pool and their function related to the various aspects in the infection route and reproduction of the late blight causing pathogen; cloning of natural R-genes and transforming cassettes of single or multiple (cisgenic) R-genes into existing varieties with proven adaptation to improve their value for consumers; selection of true to the wild type and resistant genotypes with similar qualities as the original variety; spatial and temporal resistance management research of late blight of the cisgenic genetically modified (GM) varieties that contain different cassettes of R-genes to avoid breaking of resistance and reduce build-up of epidemics; communication and interaction with all relevant stakeholders in society and transparency in what research is doing. One of the main challenges is to explain the different nature and possible biological improvement and legislative repercussions of cisgenic GM-crops in comparison with transgenic GM-crops. It is important to realize that the present EU Directive 2001/18/EC on GM crops does not make a difference between trans- and cisgenes. These rules were developed when only transgenic GM plants were around. We present a case arguing for an updating and refinement of these rules in order to place cisgenic GM-crops in another class of GM-plants as has been done in the past with (induced) mutation breeding and the use of protoplast fusion between crossable species.     

Damage and survivorship of fall armyworm (Lepidoptera: Noctuidae) on transgenic field corn expressing Bacillus thuringiensis Cry proteins

Field corn, Zea mays L., plants expressing Cry1Ab and Cry1F insecticidal crystal (Cry) proteins of Bacillus thuringiensis (Bt) Berliner are planted on considerable acreage across the Southern region of the United States. The fall armyworm, Spodoptera frugiperda (J.E. Smith), is an economically important pest during the mid-to-late season on non-Bt and some commercial Bt corn hybrids. The objective of this study was to quantify foliar injury and survivorship of fall armyworm on transgenic corn lines expressing Cry1Ab or Cry1F Bt proteins. Corn lines/hybrids expressing Cry1Ab, Cry1F, and a conventional non-Bt cultivar were evaluated against artificial infestations of fall armyworm in field trials. Larvae (second instars) of fall armyworm were placed on corn plants (V8-V10 stages). Leaf injury ratings were recorded 14 d after infestation. Hybrids expressing Cry1F had significantly lower feeding injury ratings than non-Bt corn plants. Development and survivorship of fall armyworm on Bt corn lines/hybrids were also evaluated in no-choice laboratory assays by offering freshly harvested corn leaf tissue to third instars. Transgenic corn hybrids expressing Cry1Ab or Cry1F significantly reduced growth, development, and survivorship of fall armyworm compared to those offered non-Bt corn tissue. However, 25-76% of third instars offered Bt corn leaf tissues successfully pupated and emerged as adults. These results suggest Cry1Ab has limited effects on fall armyworm; whereas Cry1F demonstrated significant reductions in foliar injury and lower survivorship compared to that on non-Bt corn tissues. Although fall armyworm is not considered a primary target for insect resistance management by the U.S. Environmental Protection Agency, these levels of survivorship could impact selection pressures across the farmscape, especially when considering that transgenic Bt cotton cultivars express similar Cry (Cry1Ac or Cry1F) proteins.     

The economic impact of investment in the Pacific Northwest potato variety development program

Genetic improvement has been the principle contributor to productivity growth in almost all field crops. The Pacific Northwest (PNW) had the highest rate of potato yield growth combined with the least amount of varietal change in any specialized major field crop-producing region in North America. A coordinated potato variety development program, jointly funded by the USDA, the three land grant universities, and the potato industry in the PNW, was established in 1984. The program developed 17 new potato varieties during the 1989–2001 period, two of them are emerging as successful processing varieties. Ranger Russet, released in 1991, and Umatilla Russet, released in 1998, possess several desired quality and production traits. The most important of these traits is 20% higher processing yield than present varieties. Since their release, there has been significant increase in the percentage of potato area planted with these new varieties. The weighted average adoption rate of these new varieties in the PNW in 2000 was about 16% of the area planted with potato. This represents 32.5% of Washington’s potato acreage, 14.3% of Oregon’s potato acreage, and 9.0% of Idaho’s potato acreage. The benefit to investments in the PNW Potato Variety Development Program attributed only to the flow of benefits from the adoption of Ranger Russet and Umatilla Russet is estimated at over $104.3 million in year 2000 and projected to increase to $213.595 million in year 2014 and thereafter. Rate of return to investment is estimated at 35%.     

Transgenic Bt corn varietal resistance against the Mexican rice borer,Eoreuma loftini (Dyar) (Lepidoptera: Crambidae) and implications to sugarcane

The Mexican rice borer, Eoreuma loftini (Dyar), attacks crops including corn, Zea mays L., rice, Oryza sativa L., sorghum, Sorghum bicolor (L.) Moench, and sugarcane, Saccharum spp. Strongly resistant varieties of any kind, native or otherwise, have not been identified. A field plot corn variety test using two transgenic Bt varieties, Pioneer 31G71, expressing the Cry1F insecticidal protein, and Golden Acres 28V81, expressing the Cry1A.105, Cry2Ab2, and Cry3Bb1 insecticidal proteins, and two non-Bt controls, Dekalb DKC 69-72 and BH Genetics 9050, all four commonly grown in the Lower Rio Grande Valley of Texas, showed that, although oviposition preference was not affected, 28V81 resisted larval stalk boring to the extent that Mexican rice borer injury was almost non-existent. Pioneer 31G71 was infested nearly as much as the controls, but larval development to adulthood was reduced by ≈70%. Rearing larvae on 5, 50, 500, and 5000 μg of corn leaf tissue per ml of artificial diet showed that, while the three lowest concentrations did not affect larval growth and development, the high concentration of 28V81 reduced survivorship to the pupal stage, decreased weight of 4-wk-old larvae, and prolonged development to pupation. Lower numbers of pheromone trap-captured adults at the edges of commercial Bt and non-Bt corn fields showed that populations were lower at the Bt cornfields, suggesting a lesser rate of adult production. Because corn is a preferred host plant over sugarcane, sorghum or rice, use of resistant transgenic Bt corn varieties will likely protect the crop from the substantial injury that can be caused by the pest. This study also suggests that Bt genes might result in similarly strong resistance when inserted in other vulnerable crops such as sugarcane.     

Genetically modified sunflower release: Opportunities and risks

Sunflower (Helianthus annuus L.) is a crop native to North America for which there are no genetically modified commercial varieties. Some of the transgenic traits incorporated in other crops have already been subjected to research and experimentation in sunflower. Several new traits have also been noted, with the most relevant of these being the aim to increase latex production. GM sunflower release would modify crop management through improved mineral nutrition, weed control, insect and disease resistance, and product quality. In this research, the traits investigated were reviewed and analyzed in connection with main crop constraints. These characters could potentially influence agro-ecosystem components and produce a significant environmental impact. In regions where sunflower coexists with wild relatives this situation could affect germplasm resources, with this being especially important at the centre of origin and where Helianthus populations established in Africa, Asia, and Europe.