代谢转基因植物的研究现状与展望

代谢转基因是通过基因工程技术对细胞内的代谢途径进行遗传修饰,进而完成细胞特性改造。代谢修饰转基因植物是一个极具商业前景的领域,在医药、环境、农业等方面已有许多成功应用的实例。综合调控代谢的基因工程策略,讨论了代谢转基因植物的研究现状,我国农业生产中存在的主要问题和代谢转基因技术对我国农业发展的意义和前景。     

转基因树木研究现状及发展趋势

通过基因工程技术将外源基因到树木基因组弥补了其传统育种手段周期长、过程繁琐、性状难以人为控制的缺点.在过去20年,树木转基因研究取得了令人鼓舞的成果,选育出多种携带外源基因的树木,并经过了限制性田间试验.国外开展树木转基因研究先于国内,在抗除草剂、抗虫、降低木质素等方面取得了显著进展,同时开展了转基因表达稳定性和安全性方面的研究.本文综合论述了近年来国内外树木转基因工作研究进展.就各国转基因树木种植概况、遗传性状改良方向、田间试验情况进行了介绍和总结,分析了存在的问题和未来发展的趋势.以期为我国从事林木基因工程研究的科研工作者以及政府决策部门提供借鉴,以促进我国树木基因工程的研究和发展.     

小麦转基因技术研究进展

小麦是我国的主要粮食作物,对其进行基因工程改良已成为研究的热点。近年来,利用转基因技术以提高小麦产量、改善品质、增强抗病虫和抗逆能力等相关研究日趋深入广泛。主要对目前小麦转基因研究现状进行综述,包括表达载体、报告基因与选择标记基因、目标基因、受体材料及转化方法等;并对当前小麦转基因技术存在的问题及育种潜力分析和展望。     

长链多不饱和脂肪酸的替代来源——转基因油料作物

长链多不饱和脂肪酸(LCPUFA)对人体健康和发育具有极为重要的作用.由于海洋鱼类资源过度捕捞和环境污染的加剧,长链多不饱和脂肪酸的来源日益枯竭.利用转基因油料作物生产LCPUFA,特别是DHA和EPA成为目前研究的热点.归纳了LCPUFA合成代谢途径相关基因的最新研究进展,描述了利用植物基因工程合成长链多不饱和脂肪酸(特别是EPA和DHA)取得的主要成果,讨论了影响转基因油料作物合成DHA和EPA的关键因素,最后对利用转基因油料作物合成DHA和EPA的研究前景进行了展望.     

植物脂肪酸代谢途径遗传调控的研究进展

目前,利用传统育种方法改良油料作物脂肪酸组分已取得巨大成功,通过有性杂交、X-射线或EMS处理等方法都可用来修饰存在于油菜中脂肪酸的性质。国外已培育出高棕榈酸、高或低亚油酸、高油酸和无芥酸的油菜品种。但由于油料作物基因池(Gene Pool)的局限性使得育种学家不得不寻找其他种质资源。随着基因克隆和遗传转化技术的进步,通过基因工程改良油料作物品质已成可能。本文主要介绍了植物脂肪酸的代谢途径以及通过操纵TAG的生物合成来改变油的成分等研究,其中主要包括脂肪酸链长度的改良、饱和度改良、增加脂肪酸含量以及新的不饱和脂肪酸的改良等方面。不久的将来,转基因油料作物中将会产生更有价值的脂肪酸造福于人类。     

斑马鱼基因工程的研究进展

对国内外斑马鱼基因工程研究进展。包括最近获得的大批转基因斑马鱼品系、靶向筛选的转基因斑马鱼、斑马鱼转基因技术的发展和斑马鱼基因工程的热点问题与应用前景进行了综述。指出我国已建立日趋成熟的斑马鱼转基因技术、细胞核移植技术和染色体组操作技术,具有斑马鱼细胞遗传学和胚胎学基础,我国有望在不久的将来获得定向整合的基因工程斑马鱼,并推动生物技术应用研究领域的进步和发展。     

抗虫转基因甘蔗的培育及其抗性丧失的防控策略

由于甘蔗存在遗传背景复杂和抗虫种质资源缺乏的问题,造成甘蔗常规抗虫育种远远落后于其他作物的现状。基因工程为抗虫甘蔗的育种提供了一条崭新的途径。经过资料收集和整理并结合作者所在研究团队的研究成果,综述了近年来国内外抗虫转基因甘蔗的培育现状。首先介绍了甘蔗转基因遗传转化系统及其转基因的遗传稳定性研究的新发展,然后重点介绍了国内外在抗虫转基因甘蔗研究方面取得的突破性研究进展,尤其在通过Bt基因的改造和抗虫基因聚合等策略来防止转基因甘蔗的抗虫性下降甚至丧失等方面进行了详细的阐述,旨在为今后抗虫转基因甘蔗的育种工作提供参考。     

中国畜牧业的概况

由863生物技术领域第一主題专家组发起和组织的首次转基因动物学术讨论会最近在北京召开。出席会议的有863第一主题动物基因工程育种两个专题的主要研究人员,特邀参加会议的有关专家,国家科委、农业部和中国科学院有关部门的负责人和工作人员近五十人,第一主题专家组洪孟民、朱立煌、陈受宜、许智宏和朱裕鼎出席了会议。 会议期间首先由专家组传达了宋健同志五月初在上海“生物领域战略目标汇报会”上的讲话精神。会议对国内外情况,包括我国畜牧业发展概况。农业科学研究战略、我国常规家畜育种技术的发展现状与生物技术在畜牧业上的应用前景、我国湖北白猪的育种技术和我国家畜疫病情况,以及哺乳动物和鱼类基因工程、细胞工程育种、家畜性别控制研究等方面的国外动态作了介绍。这些综述使与会人员既了解到国际上在转基因动物研究中取得的进展和碰到的问题,也了解了我国生产实际对转基因动物生产技术等新技术的要求和从事这方面研究所需要的背景知识及相关知识。 为了促进转基因动物研究在我国的迅速开展,我编辑部受863生物技术领域第一主题专家组的委托出版了这部“转基因动物专集”。     

Bt杀虫基因研究现状与趋势

Bt(Bacillus thuringiensis)是一种革兰氏阳性昆虫病原菌,对哺乳动物等非靶标生物安全无害,cry基因、cyt基因、vip基因编码的杀虫蛋白是其主要活性物质.目前,Bt除了用作生物杀虫剂外,表达Bt杀虫蛋白的转基因抗虫植物也已经被广泛用于害虫的防治,Bt在应用方面取得的巨大成功,极大地促进了该领域的研究发展.本文对Bt杀虫基因克隆技术、Cry蛋白结构多样性、杀虫基因命名与专利保护、研究论文发表等现状与趋势进行分析,发现我国的Bt基础研究和应用基础研究已经与国际接轨,但是产业化明显滞后,企业投入偏少.从发展趋势来看,我国在该领域仍然有较大的发展空间,参考美国转基因作物产业化与企业创新产出的时序关系,随着我国转基因作物向产业化推进,企业的研究与创新将成为一个新的增长点.     

ABA相关基因抗旱基因工程研究进展

干旱是影响植物生长发育的重要因素之一。ABA在植物生长发育及应对胁迫反应方面发挥着重要的作用。随着分子生物学等相关学科的快速发展,人们对ABA合成及信号通路相关基因的研究取得了长足进展,并进行了转基因抗旱基因工程研究。对ABA相关基因抗旱基因工程研究进展进行了综述。     

基因工程在农作物育种上研发应用新进展

以文献调研结果为依据,概述了基因工程的基本概念与基本模式,外源DNA导入的方式与表达的条件;应用基因工程培育优质、高产、抗病、抗虫、抗除草剂与抗逆性强农作物品种的进展;预测并展望了基因工程在实现农业现代化目标中的作用、开发应用重点与前景。     

Prevention of preharvest aflatoxin contamination through genetic engineering of crops

Current practices on prevention of aflatoxin contamination of crop species include time consuming, expensive agronomic practices. Of all the methods available to-date, conventional breeding and/or genetic engineering to develop host plant-based resistance to aflatoxin-producing fungi appear to be valuable for several reasons. However, breeding for disease-resistant crops is very time consuming, especially in tree crops, and does not lend itself ready to combat the evolution of new virulent fungal races. Moreover, availability of known genotypes with natural resistance to mycotoxin-producing fungi is a prerequisite for the successful breeding program. While it is possible to identify a few genotypes of corn or peanuts that are naturally resistant toAspergillus we do not know whether these antifungal factors are specific toA. flavus. In crops like cotton, there are no known naturally resistant varieties toAspergillus. Availability of transgenic varieties with antifungal traits is extremely valuable as a breeding tool. Several antifungal proteins and peptides are available for genetic engineering of susceptible crop species, thanks to the availability of efficient modern tools to understand and evaluate protein interactions by proteomics of host, and genomics and field ecology of the fungus. Transgenic approaches are being undertaken in several industry and academic laboratories to prevent invasion byAspergillus fungi or to prevent biosynthesis of aflatoxin. Recent trends in reducing aflatoxin contamination through genetic engineering of cultivated crop species with antifungal proteins are summarized in this report. Presented at the EU-USA Bilateral Workshop on Toxigenic Fungi & Mycotoxins, New Orleans, USA, July 5–7, 2005     

花生抗病基因分离克隆研究进展

花生是重要的油料作物和经济作物。近年来多种病害严重威胁着花生产业的发展,筛选花生抗病基因并对其进行研究成为花生抗性育种的新热点。结合抗病基因分离克隆在花生育种工作和遗传研究等领域逐渐显现的广阔前景,我们简要综述了国内外花生抗病基因分离克隆的研究现状,介绍了抗病基因分离克隆的类型及特点,并探讨了今后的研究方向。     

Improving salinity tolerance of plants through conventional breeding and genetic engineering: An analytical comparison

The last century has witnessed a substantial improvement in yield potential, quality and disease resistance in crops. This was indeed the outcome of conventional breeding, which was achieved with little or no knowledge of underlying physiological and biochemical phenomena related to a trait. Also the resources utilized on programs involving conventional breeding were not of great magnitude. Plant breeders have also been successful during the last century in producing a few salt-tolerant cultivars/lines of some potential crops through conventional breeding, but this again has utilized modest resources. However, this approach seems now inefficient due to a number of reasons, and alternatively, genetic engineering for improving crop salt tolerance is being actively followed these days by the plant scientists, world-over. A large number of transgenic lines with enhanced salt tolerance of different crops can be deciphered from the literature but up to now only a very few field-tested cultivars/lines are known despite the fact that considerable resources have been expended on the sophisticated protocols employed for generating such transgenics. This review analytically compares the achievements made so far in terms of producing salt-tolerant lines/cultivars through conventional breeding or genetic engineering.     

Genetic engineering of crops as potential source of genetic hazard in the human diet.

The benefits of genetic engineering of crop plants to improve the reliability and quality of the world food supply have been contrasted with public concerns raised about the food safety of the resulting products. Debates have concentrated on the possible unforeseen risks associated with the accumulation of new metabolites in crop plants that may contribute to toxins, allergens and genetic hazards in the human diet. This review examines the various molecular and biochemical mechanisms by which new hazards may appear in foods as a direct consequence of genetic engineering in crop plants. Such hazards may arise from the expression products of the inserted genes, secondary or pleiotropic effects of transgene expression, and random insertional mutagenic effects resulting from transgene integration into plant genomes. However, when traditional plant breeding is evaluated in the same context, these mechanisms are no different from those that have been widely accepted from the past use of new cultivars in agriculture. The risks associated with the introduction of new genes via genetic engineering must be considered alongside the common breeding practice of introgressing large fragments of chromatin from related wild species into crop cultivars. The large proportion of such introgressed DNA involves genes of unknown function linked to the trait of interest such as pest or disease resistance. In this context, the potential risks of introducing new food hazards from the applications of genetic engineering are no different from the risks that might be anticipated from genetic manipulation of crops via traditional breeding. In many respects, the precise manner in which genetic engineering can control the nature and expression of the transferred DNA offers greater confidence for producing the desired outcome compared with traditional breeding.     

Production of nutritionally desirable fatty acids in seed oil of Indian mustard (Brassica juncea L.) by metabolic engineering

Development of a designer oilseed crop with improved yield attributes and enhanced nutritional quality for the benefits of mankind and animal husbandry is now achievable with the combination of genetic engineering and plant breeding. In spite of their immense importance, the fatty acid profiles of most oilseed crops are imbalanced that necessitate the use of metabolic engineering strategies to overcome the various shortfalls in order to improve the nutritional quality of these edible oils. Indian mustard (Brassica juncea L.), being one of the important oilseed crops in Indian subcontinent naturally contains ~50 % nutritionally undesirable very long chain unsaturated fatty acids (VLCUFAs), e.g. erucic acid (C_22:1). For the purpose of nutritional improvement of B. juncea seed oil, several metabolic engineering strategies have been employed to divert the carbon flux from the production of VLCUFAs to other important fatty acids. Stearic acid, being a saturated but nutritionally neutral fatty acid, is naturally inadequate in most of the conventional oil seeds. Due to its neutral effect on consumer’s health and as an important industrial ingredient, increased in planta production of stearic acid in the seed oil not only helps in reduction of production cost but also lessens the trans fatty acid production during commercial hydrogenation process. In this review metabolic engineering strategies to minimize the VLCUFAs along with increased production of stearic acid in the seed oil of B. juncea are discussed, so that further breeding attempts can be made to improve the nutritionally desirable fatty acid profile in the suitable cultivars of this important oilseed crop.     

Regulating transgenic crops sensibly: lessons from plant breeding, biotechnology and genomics

The costs of meeting regulatory requirements and market restrictions guided by regulatory criteria are substantial impediments to the commercialization of transgenic crops. Although a cautious approach may have been prudent initially, we argue that some regulatory requirements can now be modified to reduce costs and uncertainty without compromising safety. Long-accepted plant breeding methods for incorporating new diversity into crop varieties, experience from two decades of research on and commercialization of transgenic crops, and expanding knowledge of plant genome structure and dynamics all indicate that if a gene or trait is safe, the genetic engineering process itself presents little potential for unexpected consequences that would not be identified or eliminated in the variety development process before commercialization. We propose that as in conventional breeding, regulatory emphasis should be on phenotypic rather than genomic characteristics once a gene or trait has been shown to be safe.     

Genetic engineering approaches to enhance oil content in oilseed crops

Oilseed crops play an important role in the agricultural economy. Apart from being an integral component of human diet and industrial applications, they are also gaining importance as replacement to fossil fuels for meeting the energy needs. The last two decades have been marked by several important events in genetic engineering and identification of gene targets for enhancing seed oil content in oilseed crops, and will aid the successful development of new generation high yielding oil crops. Specifically, genetic engineering has shown real breakthrough in enhancing oil content in oilseed rape, camelina, soybean and maize. Moreover, ongoing research efforts to decipher the possibilities of genetic modifications of key regulators of oil accumulation along with physiological and biochemical studies to understand lipid biosynthesis will set a platform to produce transgenic oilseed crops with enhanced oil content. In this review, we briefly describe different genetic engineering approaches explored by different researchers for enhancing oil content. Further, we discuss a few promising and potential approaches and challenges for engineering oil content in oilseed crops.     

Improving Salinity Tolerance in Cereals

Cereals are grown in almost every region of the world and are exposed to a variety of environmental stresses that severely affect their growth and grain yield. Of various abiotic stresses, salinity is one of the more significant threats to cereal crops. To ensure food security, there is a need to adopt strategies to overcome this specific threat. Undoubtedly, plant scientists have been exploiting a variety of approaches to achieve enhanced crop productivity on salt affected soils. Of the various biotic approaches, conventional breeding, marker-assisted selection and genetic engineering to develop salt-tolerant lines/cultivars of cereals all seem plausible. Some success stories have been reported for improvement in salt tolerance of wheat and rice, but are scarce for other cereals. A number of barriers to the development of salt-tolerant cultivars/lines have been identified and include a lack of knowledge about the genetics of crops, their physiological and biochemical behavior, wide variation in environmental conditions, and the complex polygenic nature of the salt tolerance character. This review focuses on how improvements have been made in salt tolerance in cereals through different biotic means, such as conventional breeding, marker assisted selection and genetic engineering.     

Genetic engineering approaches to improve bioethanol production from maize

Biofuels such as bioethanol are becoming a viable alternative to fossil fuels. Utilizing agricultural biomass for the production of biofuel has drawn much interest in many science and engineering disciplines. As one of the major crops, maize offers promise in this regard. Compared to other crops with biofuel potential, maize can provide both starch (seed) and cellulosic (stover) material for bioethanol production. However, the combination of food, feed and fuel in one crop, although appealing, raises concerns related to the land delineation and distribution of maize grown for energy versus food and feed. To avoid this dilemma, the conversion of maize biomass into bioethanol must be improved. Conventional breeding, molecular marker assisted breeding and genetic engineering have already had, and will continue to have, important roles in maize improvement. The rapidly expanding information from genomics and genetics combined with improved genetic engineering technologies offer a wide range of possibilities for enhanced bioethanol production from maize.