章节大纲

  • lesson content

    Why would anyone grow plants like this?
    ::为什么有人会这样种植物?

    Developing better crops is a significant aspect of . But what is meant by "better?" Crops that are resistant to damage from or droughts? Crops that taste better? Crops that last longer? Crops that can grow anywhere? How do you feed over 7,000,000,000 people? With biotechnology. Crops developed with biotechnology must have a significant role in the world's future. And it all starts in the lab.
    ::开发更好的作物是其中的一个重要方面。但是,“更好”是指什么?耐受破坏或干旱影响的作物?品尝较好的作物吗?耐久的作物?耐久的作物?可以在任何地方生长的作物?如何养活超过7000万人?生物技术:生物技术开发的作物必须在世界的未来中发挥重要作用。所有这一切都从实验室开始。

    Applications of DNA Technology: Agriculture
    ::DNA应用技术:农业

    Biotechnology has many other useful applications besides those that are medically related. Many of these are in agriculture and food science . These include the of transgenic crops - the placement of genes into plants to give the crop a beneficial trait. Benefits include:
    ::除了与医学有关的应用外,生物技术还有其他许多有用的应用,其中许多是农业和食品科学方面的应用,其中包括转基因作物 -- -- 将基因植入植物,使作物受益。

    • Improved yield from crops.
      ::作物产量提高。
    • Reduced vulnerability of crops to environmental stresses.
      ::降低作物对环境压力的脆弱性。
    • Increased nutritional qualities of food crops.
      ::提高粮食作物的营养质量。
    • Improved taste, texture or appearance of food.
      ::改善食物的味道、质地或外观。
    • Reduced dependence on fertilizers, pesticides and other agrochemicals.
      ::减少对肥料、杀虫剂和其他农用化学品的依赖。
    • Production of vaccines .
      ::生产疫苗。

    lesson content

    Creating a Transgenic Crop. A transgenic crop is genetically modified to be more useful to humans. The bacterium transfers the T-DNA (from the Ti plasmid) fragment with the desired gene into the host plant's nuclear genome.
    ::创建转基因作物。转基因作物经过基因改造,对人类更有用。细菌将T-DNA碎片(从Tiplasmid)与所希望的基因转移至宿主工厂的核基因组。

    Improved Yield from Crops
    ::提高作物产量

    Using biotechnology techniques, one or two genes may be transferred into a crop to give a new trait to that crop. This is done in the hope of increasing its yield. However, these increases in yield have proved to be difficult to achieve. Current genetic engineering techniques work best for single gene effects - that is traits inherited in a simple Mendelian fashion. Many of the genetic characteristics associated with crop yield, such as enhanced growth, are controlled by a large number of genes, each of which just has a slight effect on the overall yield. There is, therefore, still much research, including plant genetic research, to be done in this area.
    ::利用生物技术技术,可将一两个基因转移到作物中,以给作物带来新的特征。这样做是为了增加产量,但是,产量的增加证明难以实现。目前的遗传工程技术对单一基因效应最有效,即以简单Mendelian方式传承的基因效应。许多与作物产量有关的遗传特征,如生长增加,都受到大量基因的控制,每一种基因都只是对总产量略有影响。因此,在这方面还有许多研究,包括植物基因研究。

    Reduced Vulnerability to Environmental Stresses
    ::减少对环境的脆弱性

    Crops are obviously dependent on environmental conditions. Drought can destroy crop yields, as can too much rain or floods. But what if crops could be developed to withstand these harsh conditions? Biotechnology will allow the development of crops containing genes that will enable them to withstand biotic and abiotic stresses. For example, drought and excessively salty soil are two significant factors affecting crop productivity. But there are crops that can withstand these harsh conditions. Why? Probably because of that plant's genetics . So biotechnologists and plant geneticists are studying plants that can cope with these extreme conditions, trying to identify and isolate the genes that control these beneficial traits. The genes could then be transferred into more desirable crops, with the hope of producing the same phenotypes in those crops.
    ::作物显然依赖环境条件。 干旱会破坏作物产量,而降雨或洪水可能过多。 但如果作物可以发展以承受这些恶劣条件,会怎样? 生物技术将允许开发含有基因的作物,使其能承受生物和非生物压力。例如,干旱和过度盐土是影响作物生产力的两个重要因素。 但是,有些作物可以承受这些恶劣条件。为什么?可能是因为植物的遗传学原因。因此生物技术学家和植物遗传学家正在研究能够应付这些极端条件的植物,试图查明和分离控制这些有利特性的基因。然后这些基因可以转移到更理想的作物,希望在这些作物中生产同样的植物型。

    Thale cress ( Figure ), a of Arabidopsis ( A. thaliana ), is a tiny weed that is often used for plant research because it is very easy to grow and its genome has been extensively characterized. Scientists have identified a gene from this plant, At-DBF2, that confers resistance to some environmental stresses. When this gene is inserted into tomato and tobacco , the cells were able to withstand environmental stresses like salt, drought, cold and heat far better than ordinary cells. If these preliminary results prove successful in larger trials, then At-DBF2 genes could help in engineering crops that can better withstand harsh environments.
    ::Thale cress (Figure ) (Figure ) (A. Thaliana ) (A. Thaliana ) 是植物研究中经常使用的一种小杂草,因为植物研究非常容易生长,其基因组也具有广泛的特征。科学家已经从这个植物中找出了一个基因,即At-DBF2, 它对一些环境压力具有抗力。当这种基因被插入番茄和烟草中时,细胞能够比普通细胞更能承受像盐、干旱、冷热这样的环境压力。如果这些初步结果在更大的试验中证明是成功的,那么At-DBF2基因可以帮助工程作物更好地抵御严酷的环境。

    Researchers have also created transgenic rice plants that are resistant to rice yellow mottle (RYMV). In Africa, this virus destroys much of the rice crops and makes the surviving plants more susceptible to fungal infections.
    ::在非洲,这种病毒摧毁了大米作物,使幸存的植物更容易受到真菌感染。

    lesson content

    Thale cress.
    ::特莱克丝

    Increased Nutritional Qualities of Crops
    ::提高作物的营养质量

    Maybe you’ve heard over and over that eating beans is good for you. True? Well, maybe. But what if it were genetically possible to increase the nutritional qualities of food? One would think that would be beneficial to society . So, can biotechnology be used to do just that? Scientists are working on modifying in foods to increase their nutritional qualities. Also, proteins in legumes and cereals may be transformed to provide all the amino acids needed by human beings for a balanced diet.
    ::也许你已经反复听到吃豆子对你有好处了。对,也许吧。但是,如果在基因上能够提高食物的营养质素呢?人们会认为这会有益于社会。 因此,生物技术可以仅仅用于这一点吗?科学家们正在修改食物,以提高营养质。 此外,豆类和谷物中的蛋白质可以被转换为提供人类平衡饮食所需的所有氨基酸。

    Improved Taste, Texture, or Appearance of Food
    ::改善食品的品尝、质质或外观

    Have you ever gone to the grocery store, bought some fruit and never gotten around to eating it? Maybe you haven’t, but maybe your parents have. Modern biotechnology can be used to slow down the process of spoilage so that fruit can ripen longer on the plant and then be transported to the consumer with a still reasonable shelf life. This is extremely important in parts of the world where time from harvest to the consumer may be longer than in other areas. In addition to improving the taste, texture and appearance of fruit, it will also extend the usable life of the fruit. As the world grows and grows, this may become a fairly important issue. Extending the life of fruit can expand the market for farmers in developing countries due to the reduction in spoilage. This has successfully been demonstrated with the tomato. The first genetically modified food product was a tomato which was transformed to delay its ripening. Researchers in Indonesia, Malaysia, Thailand, Philippines and Vietnam are currently working on developing other delayed ripening fruits, such as the papaya.
    ::你是否去过杂货店,购买了一些水果,却从未吃过?也许你没有买过,但也许你的父母有。现代生物技术可以用来减缓变质过程,以便水果在植物上可以更成熟,然后运到保存寿命仍然合理的消费者手中。 在从收获到消费的时间可能比其他地区更长的世界地区,这一点极为重要。除了改善水果的味道、质地和外观外,它还会延长水果的可用寿命。随着世界的成长,这可能会成为一个相当重要的问题。延长水果的寿命可以扩大发展中国家农民的市场,因为腐蚀的减少。这已经用番茄成功地证明了这一点。 第一种转基因改良的食品是番茄,它已经变换成推迟了成熟期。 印度尼西亚、马来西亚、泰国、菲律宾和越南的研究人员目前正在开发其他推迟成熟的水果,如木瓜。

    Reduced Dependence on Fertilizers, Pesticides, and Other Agrochemicals
    ::减少对化肥、农药和其他农用化学品的依赖

    There is growing concern regarding the use of pesticides in agriculture. Therefore, many of the current commercial applications of modern biotechnology in agriculture are focused on reducing the dependence of farmers on these chemicals. For example, Bacillus thuringiensis (Bt) is a soil that produces a protein that can act as an insecticide, known as the Bt toxin . But it is a naturally occurring protein, not a foreign chemical. Could this protein be used in crops instead of pesticides? Traditionally, an insecticidal spray has been produced from these bacteria. As a spray, the Bt toxin is in an inactive state and requires digestion by an insect to become active and have any effect. Crop plants have now been engineered to contain and express the genes for the Bt toxin, which they produce in its active form. When an insect ingests the transgenic crop, it stops feeding and soon thereafter dies as a result of the Bt toxin binding to its gut wall. Bt corn is now commercially available in a number of countries to control corn borer (an insect like a moth or butterfly), which is otherwise controlled by insecticidal spraying.
    ::因此,现代生物技术目前在农业中的许多商业应用都侧重于减少农民对这些化学品的依赖性。例如,丁基磺酰胺(Bt)是一种可产生蛋白质的土壤,可用作杀虫剂,称为Bt毒素。但这是一种自然产生的蛋白质,而不是一种外国化学品。这种蛋白质能否用于作物而不是杀虫剂?传统上,这些细菌会产生杀虫剂喷雾。由于喷雾,Bt毒素处于不活动状态,需要昆虫消化成为活性并产生任何效果。作物作物现已设计成含有和表达Bt毒素基因的植物,这些基因以其活性形式生产。当昆虫种植转基因作物时,它停止喂食,并很快会因粘附在肠道上的Bt毒素而死亡。Bt玉米现在在一些国家可以商业上用来控制玉米播虫(如甲虫或蝴蝶),否则会受到杀虫剂喷洒的控制。

    lesson content

    Kenyans examining genetically modified insect resistant transgenic Bt corn.
    ::肯尼亚人检查转基因昆虫抗转基因Bt玉米。

    In addition to insects, weeds have also been a menace to farmers - just ask anyone with a garden how much they hate weeds. They can quickly compete for and nutrients needed by other plants. Sure, farmers can use herbicides to kill weeds, but do these chemicals also harm the crops? Can biotechnology help with this issue? Some crops have also been genetically engineered to acquire tolerance to the herbicides - allowing the crops to grow, but killing the weeds. But the lack of cost effective herbicides with a broad range of activity - that do not harm crops - is a problem in weed management. Multiple applications of numerous herbicides are routinely needed to control the wide range of weeds that are harmful to crops. And at times these herbicides are being used as a preventive measure – that is, spraying to prevent weeds from developing rather than spraying after weeds form. So these chemicals are being added to crops. This practice is followed by mechanical and/or hand weeding to control weeds that are not controlled by the chemicals. Crops that are tolerant of herbicides would obviously be a tremendous benefit to farmers ( Figure ). The introduction of herbicide tolerant crops has the potential to reduce the number of chemicals needed during a growing season , thereby increasing crop yield due to improved weed management and decreased harm to the crops.
    ::除了昆虫之外,杂草还威胁到农民 — — 只要问一个有花园的人他们有多讨厌杂草,他们就能快速竞争其他植物所需的杂草和养分。 当然,农民可以使用除草剂来杀死杂草,但是这些化学品也能伤害作物吗?生物技术能帮助这一问题吗?有些作物还经过基因改造,以获得对除草剂的耐药性 — — 允许作物种植,但杀死杂草。但是,缺乏成本有效的除草剂,而且活动范围广泛 — — 并不伤害作物 — — 是杂草管理中的一个问题。许多除草剂的多种应用通常都需要用于控制对作物有害的多种杂草。有时这些除草剂被用作预防性措施 — — 也就是说,喷洒除草剂是为了防止除草剂的生长,而不是在除草剂形式后再喷洒。因此,这些化学品被添加到作物中。这个做法是机械和/或手织除草剂来控制那些不受化学品控制的杂草,这在杂草原管理中是个问题。 作物的作物是耐性作物的多种用途,这通常都需要使用这些除草剂来控制对作物有害。 因此,作物的作物会减少作物的作物的作物的作物的种植将带来。

    In 2001, 626,000 square kilometers of transgenic crops were planted. Seventy-seven percent of the transgenic crops were developed for herbicide tolerance in soybean, corn, and cotton, 15% were Bt crops for insect resistance, and 8% were developed with genes for both insect resistance and herbicide tolerance in cotton and corn.
    ::2001年,种植了626,000平方公里的转基因作物。 77%的转基因作物用于大豆、玉米和棉花的除草剂耐药性,15%用于昆虫抗药性,8%用于棉花和玉米的抗虫性和除草剂耐药性。

    Production of Vaccines in Crop Plants
    ::作物工厂疫苗生产

    Most little children hate shots. And many children in parts of the world do not even have access to vaccines. But what if these vaccines were available in an edible form? Modern biotechnology is increasingly being applied for novel uses other than food. Banana trees and tomato plants have been genetically engineered to produce vaccines in their fruit. If future clinical trials prove successful, the advantages of edible vaccines would be enormous, especially for developing countries. The transgenic plants could be grown locally and cheaply. Edible vaccines would not require the use of syringes, which, in addition to being unpleasant, can be a source of infections if contaminated.
    ::大部分的小孩都讨厌射击。 世界上很多儿童甚至得不到疫苗。 但是,如果这些疫苗以可食用的形式提供呢?现代生物技术正越来越多地用于食品以外的新用途。 香蕉树和番茄植物已经通过基因工程在水果中生产疫苗。 如果未来的临床试验证明成功,食用疫苗的好处将是巨大的,特别是对发展中国家。 转基因植物可以在当地种植,价格低廉。 食用疫苗不需要使用注射器,除了不愉快之外,如果受到污染,也可能是感染的来源。

    Scientists have created a transgenic purple tomato that contains a cancer-fighting compound and others that have high levels of antioxidants (see Figure ). 
    ::科学家创造了一种转基因紫色番茄,其中含有一种抗癌化合物和其他抗氧化剂含量高的化合物(见图 )。

    lesson content

    Transgenic Purple Tomato. A purple tomato is genetically modified to contain high levels of antioxidants. A gene for the compound was transferred into normal red tomatoes.
    ::紫色番茄经过基因改造,含有高剂量抗氧化剂,该化合物的基因被转移到正常的红番茄中。

    Summary
    ::摘要

    • Biotechnology in agriculture includes the development of transgenic crops - the placement of genes into plants to give the crop a beneficial trait.
      ::农业生物技术包括发展转基因作物 -- -- 将基因植入植物,使作物具有有利的特性。
    • Benefits of agriculture biotechnology include improved yield from crops, reduced vulnerability of crops to environmental stresses, increased nutritional qualities of food crops, improved taste, texture or appearance of food, reduced dependence on fertilizers, pesticides and other agrochemicals, and production of vaccines.
      ::农业生物技术的好处包括提高作物产量、降低作物易受环境压力影响的程度、提高粮食作物的营养质量、改善食物的口味、质地或外观、减少对肥料、杀虫剂和其他农用化学品的依赖以及生产疫苗。

    Review
    ::回顾

    1. Describe uses of biotechnology in agriculture.
      ::描述生物技术在农业中的用途。
    2. Make a flow chart outlining the steps involved in creating a transgenic crop.
      ::绘制一个流程图,概述生产转基因作物的步骤。
    3. Describe how DNA technology can improve yield from crops.
      ::说明DNA技术如何能够提高作物产量。
    4. Discuss how DNA technology can be used to reduce vulnerability to environmental stresses. Why is it important? State an example.
      ::讨论如何利用DNA技术减少易受环境压力影响的程度,为什么重要?