Plant Genetic Engineering
植物基因工程
Key Notes: 要点
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The concept: 概念
Genetic manipulation involves inrting foreign genes or modifying the activity of existing genes. Methods to inrt foreign genes are coupled with the methods of plant tissue culture to regenerate identical populations of plants with novel characteristics.
基因操作涉及插入外源基因或者改变原有基因的活性。插入外源基因和植物组织培养技术相结合可再生出具有新特征的纯一的植物群体。
Basic genetic manipulation methods: 基因操作的基本方法
Agrobacterium tumifaciens is a soil bacterium with a plasmid that inrts foreign DNA into
圣诞快乐英文a plant. The plasmid contains a T-DNA transferred into the plant and a VIR region that facilitates transfer of the T-DNA. Binary vectors for genetic engineering consist of one plasmid containing the VIR region and a cond containing the T-DNA including the foreign DNA. Where the Agrobacterium system cannot be ud, direct gene transfer techniques may be employed, for instance using a DNA particle gun.
lenticulargrass是什么意思 农杆菌是一种土壤细菌，它含有一个将外源DNA插人植物体的质粒。质粒含有一段转移到植物体中的DNA和有利于T-DNA转移的VIR区(毒性区)。用于 基因工程的双载体系统由一个含有VIR区的质粒和一个含有T-DNA的质粒组成，其中T-DNA含有外源基因。不能利用农杆菌系统的植物可以采用直接的基 因转移技术，如利用DNA粒子枪。
Possibilities of genetic manipulation: 基因操作的可能性
The aims of genetic manipulation are to enhance agriculture by modifying crop plants, to minimize inputs and loss, and maximize yields and value. To date, crops have been engineered for herbicide tolerance, inct and virus resistance and post-harvest quality. In the future, a much broader spectrum of improvements of wider benefit is propod.
基因操作的目的是通过改变农作物的基因组成从而尽量降低投入和损失，尽量提高农作物的产量和品质。迄今为止，已经针对农作物的耐除草剂、抗虫和抗病毒的特性以及采后品质进行了基因操作。今后将在更广泛程度上增加更大的利益。
by the wayRisks of genetic manipulation: 基因操作的风险
Risks identified include: environmental, such as cross pollination and gene transfer with native species; food safety, mainly the transfer of antibiotic resistance to bacteria, allergies and toxicity; and socio-economic, food supply in the hands of few multinational companies.
基因操作也有风险，被人们一致认可的基因操作风险包括：环境风险，如异花授粉与本地植物的基因转移；食品安全，主要是对细菌、过敏反应和毒素的抗生素抗性的转移；社会经济风险，食品供应掌握在少数跨国公司手中。
Related topics: 相关题目
Plants as food(N1)
儿童节快乐英文怎么说Plant cell and tissue culture(01) 植物细胞和组织培养
Plant breeding(02) 植物育种
活板翻译The concept: 概念
mid autumn Genetic engineering (recombinant DNA technology) involves inrting foreign genes or modifying the activity of existing genes. A soil bacterium, Agrobacterium tumifaciens, naturally inrts its own bacterial genes into plant genomes. The result is a crown gall, a swelling of the stern at soil level caud by over-production of auxins, and cytokinins produced by enzymes encoded by genes transferred from the bacterial genome. The regeneration of entire plants from single cells or explants has been carried out for many decades to produce clonal populations of plants. Together, the two provide genetic engineers the tools for the inrtion of genes from another organism into a plant and the regeneration of a clonal population of that plant. All the members of that population will express the foreign gene.
基因工程(重组DNA技术)涉及插入外源基因或改变原有基因的活性。农杆菌是一种土壤细菌。自然情况下，它可以将自身的细菌基因插入植物基因组中。结果在 土壤表面附近的茎干处形成一个膨大的冠瘿，这是由于生长素的过表达以及由转移的细菌基因组编码的酶合成的细胞分裂素所致。从单细胞或外植体再生出完整植株 来生产植物的克隆群体已进行了几十年。这两种技术为将另外一种生物的基因插入植物体和植株的克隆群体提供了基因工程工具。克隆群体的所有成员都将表达外源 基因。
Basic genetic manipulation methods: 基因操作的基本方法
Agrobacterium tumifaciens contains a plasmid, a circular piece of DNA parate from the bacterial chromosome, known as the Ti plasmid. This plasmid contains genes which will be randomly inrted into the plant genome (transferred or T-DNA) and genes involved in the transfer of the DNA (the VIR or virulence region for infection). Normally, the T-DNA region contains genes for auxin and cytokinin biosynthesis and for amino acid and sugar derivative production. For genetic manipulation, the Ti plasmid is modified by the removal of the genes within the T-DNA region using restriction enzymes that cut DNA
at specific nucleotide quences. The action of the restriction enzymes leaves a linear strand of DNA with 'sticky' ends where the nucleotides are unpaired and therefore able to join to a complementary nucleotide quence in another strand of DNA. 羹怎么读
农杆菌含有一个与细菌染色体相分离的环形质粒，称为Ti质粒(Ti-plasmid)。这个质粒含有随机插入植物基因组的基因，即转化DNA(T- DNA)，以及参与该T-DNA转移的基因即毒性区(VIR)。通常T-DNA区都含有生长素和细胞分裂素合成基因以及氨基酸和糖类衍生物合成基因。为了 利于基因操作，用限制酶在特定的核苷酸序列处除去T-DNA区内部的基因以进行质粒修饰。限制酶的作用后留下具有黏性末端的线形DNA，黏性末端处的核苷 酸是不配对的，因此可以与另外一条DNA互补的核苷酸序列结合。
A gene of interest in another organism (animal, plant or bacterium) is identified and prepared for inrtion into the Ti plasmid. It is cut out of its host with the same restriction enzymes ud to prepare the Ti plasmid, again leaving sticky ends. This cut DNA is then mixed with the modified plasmid DNA, the two DNA strands join at their sticky ends and are aled together by the enzyme, DNA liga, to form a recombinant plasmid. The gene inrted must contain a promoter which will allow it to be expresd in the plant.
鉴定和准备好插入Ti质粒的另外一种生物(动物、植物和细菌)中的目的基因，它可以通过与用于制备Ti质粒相同的限制酶从该生物上切下来，也留有黏性末 端。将切下来的DNA与修饰过的质粒DNA混合，这两条DNA片段在黏性末端结合，由DNA连接酶将它们封好从而形成重组质粒。插入的基因必须含有能让其 在植物体中表达的启动子。
