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  3. Scientists Make Plants Grow Faster Genetic researchers have accelerated a

Scientists Make Plants Grow Faster Genetic researchers have accelerated a

游客2023-12-28  24
问题    Scientists Make Plants Grow Faster
   Genetic researchers have accelerated a plant’s growth by making its cells split faster — a technique that could someday lead to healthier crops, shorter growing seasons and less use of herbicides. One outside scientist called the findings astonishing. But the technique needs more testing on a range of plants, and public fear of genetically modified food is jeopardizing support for such experiments, especially in Europe, researchers said. The experiment, reported Thursday in the journal Nature, was carried out by a team at Cambridge University. The researchers first took a gene promoting cell division from inside the arabidopsis plant, a flowering weed often used for genetic experiments. They transplanted that gene into a tobacco plant. There, in an especially potent form, the gene produced large amounts of a protein that, in combination with other chemicals naturally in the tobacco, made the plant’s cells divide more quickly at the tips of roots and shoots. Within a month after planting, the altered tobacco grew as much as twice as tall as other tobacco plants. Ultimately, the other plants caught up, and both groups then appeared identical in all ways. "It’s sort of like they’ve been able to make the plant go full throttle," said plant growth biologist John Schiefelbein at the University of Michigan. The leader of the study, Claire Cockcroft, said it is conceivable that the technique could be transferred to other species. Such plants, which probably would take years to develop commercially, might allow an extra planting in some climates or the introduction of crops in places where the growing season is too short, researchers said. The quick-growth plants would presumably take hold more easily, requiring less chemical herbicide to knock out weeds. Such plants might make easier and cheaper sources of some drugs.
   In scientific circles, the British research may also help settle an intense debate over what makes plants grow. Some argue, like these researchers, that something at the cellular level switches on growth; others look to hormones or other chemicals at a higher level of the plant’s makeup. "This is astonishing. Normally you would expect growth regulation to be more complicated, " said plant researcher Xuemin Wang at Kansas State University. " This has huge implications in terms of how we look at plant growth. " Biotechnology companies have genetically manipulated fruits and vegetables to make them more attractive or resistant to insects and disease. Genetic work has shown some early promise for faster growth, too. But previous attempts to boost growth through faster cell division have produced more cells — but smaller ones — and no overall growth. Scientists said such work is safe, with little chance of accidentally turning an unwanted plant into a fast-growing weed. After all, crops have been selectively bred for decades to bring out certain traits. However, ethicist Jeffrey Burkhardt at the University of Florida’s Institute of Food and Agricultural Sciences said selective breeding takes perhaps 15 years, giving scientists ample time to see the implications. "With the new biotechnology, you’re potentially moving traits in and out within a year," he said. He said federal agencies should review genetically modified plants more carefully over a longer time. But he thinks some may prove worthy.
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答案    科学家们研究出加速植物生长的方法
   基因研究人员用加速植物细胞分裂的方法使植物生长得更快——这种技术有朝一日会培育出更健壮的农作物，缩短生长周期并使除草剂的使用减少。一位非此领域的科学家称这是令人惊异的研究成果。但研究人员说，这项技术还需要对多种植物进行更多的实验，而公众对转基因食品的恐惧会对此类实验获得支持相当不利，特别是在欧洲。这项由剑桥大学的一组研究人员进行的研究发表在周四出版的《自然》杂志上。研究人员首先从一种经常用于基因实验的开花野草，阿布属类植物中取出促进细胞分裂的基因，然后把这种基因移植到一种烟草植物上。由于采用了某种特别有效的方法，这种基因产生出大量的蛋白质，蛋白质与烟草植物中自然生成的另一种化学物质相结合，使得烟草植物的根和嫩枝的尖端部分的细胞以更快的速度分裂。这种改造过的烟草种植后不到一个月，就长得比其它烟草高大一倍，但其它烟草最终赶了上来，这两组植物在各方面看来都完全一样。密歇根大学的植物栽培生物学家约翰-希费贝恩说：“就好像他们能使植物开足马力疯长一样。”领导这项研究的克莱尔-科克罗夫特说，可以想象，这种技术应该能应用于其它种类的植物。研究人员说，这类植物也许还要几年时间才能进入商业应用阶段，在某些气候条件下它可能会多生长一茬，或者能把它引进到生长季节特别短的地区。估计这种快速生长的植物生根很容易，消灭野草所需的除草剂也用得较少，这种植物也许可以成为生产一些药品的更易制造、更廉价的原料。
   在科学界，英国的这项研究也许有助于结束是什么使植物得以生长的激烈争论。有一部分人与这些英国研究人员的看法相同，认为是细胞层次上的某些物质激发了植物生长，另一些人认为是激素或植物结构中更深层次上的其它化学物质激发了植物生长。堪萨斯州立大学的植物研究人员王学敏说：“这是令人惊奇的事情。人们通常认为植物生长的规律是很复杂的。这对于我们对植物生长的看法具有重大意义。”已有多家生物技术公司通过基因处理，获得了外表更诱人或能抗虫害和疾病的水果与蔬菜。基因工程已经显示出有可能加快植物的生长，但过去通过促进细胞分裂而加速植物生长的实验结果是产生了更多、但更小的细胞，而不是总体的生长。科学家们说，这类研究工作是安全的，那些不需要的植物意外突变成疯长的野草的可能性很小。毕竟，几十年来人们一直在对农作物进行选择性培育，来培养某种变种。然而，佛罗里达大学食品和农业科学研究所的伦理学家杰夫里-柏哈特说，选择性育种需要大约15年的时间，科学家有充裕的时间对其中的诸多因素进行研究。他说：“新的生物技术使你有可能在一年内改变植物的特性。”他认为联邦政府有关部门应该用更长的时间仔细审查基因改良植物，但他认为有些植物也许是有价值的。
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