【这是nature有关转基因监管的第二篇报道，原文附在后面，不足之处，敬请指点！谢谢！】 现在是修改几十年前制定的遗传工程作物管理条例的时候了。 Scotts Miracle-Gro公司的研究人员有一个绿色未来的美景。这家位于俄亥俄州马里斯维尔专注于草坪的公司打算研发一种矮肯塔基兰草，这种草比常规的肯塔基兰草减少了维护次数。但有一个令人纠结的问题：这种草与那些生命力顽强的杂草不一样，没有竞争优势。这不是问题，Scotts公司解释道，将生产一种抗除草剂的矮草使得屋主可以将杂草在萌芽状态就去除。 当美国农业部（USDA)告诉Scotts公司他们对这种草没有监管权时，这种转基因肯塔基兰草成了本月（七月）的头条新闻。结果，Scotts公司研发的转基因植物无需监管就可以自由地上市。 这是由于历史原因造成的。美国遗传修饰作物管理条例依赖于植物有害物法案授权和控制植物有害物，因此美国农业部通常根据产生植物有害物的方式来监管转基因作物。这是一个奇异的方法，假定用来转基因的工具是低风险的。但它有某种优点，转基因第一次研发出来时，外源基因常常通过一种对其他植物来说是致命病原物的细菌介导插入植物基因组中。一旦插入到合适的地方，外源基因在一系列来自植物病毒的遗传元件调控它的表达。 为了避开这一点，Scotts公司没有利用植物有害物及其元件来创建转基因草。这使得创建新的转基因草花费了更大的力气，但公司解释说最新技术的利用是为了更多的消费者能够接受和避免传统遗传工程方法的专利——所以它是值得的。因此，他们从现有的植物基因组中挖掘宝藏，从模式植物拟南芥中获得了一个除草剂抗性基因，使其与来源于玉米和水稻的驱动基因表达的启动子融合，并通过基因枪轰击将外源基因导入肯塔基兰草的基因组中。 这个技术并不是唯一可以超出USDA监管条例的转基因方法。自从1986年管理条例制定以来，植物分子生物学家取得了长足的进步，尤其是在植物遗传学基本原理的理解和知道这样操作基因表达的技术上。现在可以对基因组的特定位置进行遗传改变，外源基因根本就不用整合进植物基因组就可以在植物细胞中表达。基因的表达可以利用RNA分子进行调控——甚至一些案例中可以针对一种病原物的侵染做出反应。 这些先进的技术商业化应用还需要数年时间，但是监管者必须为这种情况做好准备。孟山都利用RNA干涉调控内源基因表达的转基因大豆正在等待USDA的决定。 USDA和其他管理者需要重新考虑他们对转基因作物的定义和监管了。如果一种作物研究人员利用遗传工程从植物基因组中敲出一个片段，需要怎样的管理条例？同样的指导方针是否适用于半剂量表达抗虫和抗除草剂基因的作物，是否适用于没有利用植物有害物及其元件的转基因作物？这些问题对于美国的遗传修饰作物管理条例是非常重要的，它们依据的是创建转基因作物方法的过程，而不是依据遗传工程的最终结果。 欧洲委员会正在处理这个问题，已经委托进行一个研究，研究怎样将新技术产生的转基因作物列入欧盟的转基因目录中。类似的，USDA生物技术和21世纪农业咨询委员会也关注这个问题。 但在2008年发布的草案中，USDA的建议是改变它对转基因作物的管理权力，没有补充新技术带来的挑战。USDA关于肯塔基兰草的裁定对于农业生物技术而言具有决定性的。据估计世界上农产品每年必须增产25%才能满足日益增长的食物和生物能源的需求。能够满足这种需要的农业生物技术进步带来了许多争议，其中部分来源于转基因作物。产业界，特别是小公司，在他们投资开发新技术之前需要知道这些作物将得到怎样的监管。 由于技术进步产生新的转基因方法，解决了利用外源基因带来的长期不安和插入到基因组特定位置解决目标基因的不稳定性，使得转基因作物能够获得更为广泛的接受。但那些半信半疑的消费者对能够接受完全规避监管的转基因作物是心怀疑虑。 附原文： Growing pains It is time to update decades-old regulation of genetically engineered crops. Researchers at Scotts Miracle-Gro have a vision of a greener future. The lawn-care company, based in Marysville, Ohio, wants to develop a dwarf grass that needs less frequent maintenance than standard Kentucky bluegrass. But there is a catch: such grass is unlikely to stand up to weeds. No problem, the company reasons,it will make a dwarf grass that is resistant to herbicide to help homeowners to nip those weeds in the bud. Development of this genetically modified (GM) Kentucky bluegrass made headlines this month when the US Department of Agriculture (USDA) told Scotts that it did not have the authority to regulate it (see page 274). As a result, Scotts is free to start selling its new crop without oversight. The reason for this is historical. US regulation of GM crops relieson its authority to control plant pests, and so the USDA has regulated crops on the basis of the way plant-pest-based tools are used to make them. It is a bizarre approach, given the low pest risk from the tools. But it had some merit when it was first developed because foreign genes were often inserted into the plant genome by a bacterium that can be lethal to some plants. Once in place, the expression of the foreign gene was guided by a series of genetic elements pulled from plant viruses. To get around this, researchers at Scotts made GM grass without using plant pests. It took more work, but the company reasoned that the streamlined regulation — as well as possible greater consumer acceptance and relief from the patent stranglehold on more traditional genetic-engineering methods — would make it worthwhile. So they mined the wealth of plant genomic data now available, snipped a herbicide-resistance gene from the model plant Arabidopsis thaliana, sewed it to genetic elements pulled from maize (corn) and rice to drive the gene’s expression, and used a gene gun to blast it into the Kentucky bluegrass genome. This technique is not the only GM method likely to fall outside USDA regulations. Plant biologists have made tremendous strides since the current rules were cobbled together in 1986, advancing both our fundamental understanding of plant genetics and the technical know-how in manipulating gene expression. Genetic changes can now be made at specific sites in the genome, and foreign genes can even be expressed in plant cells without integrating them into the genome at all. And gene expression can be regulated using RNA molecules — including, in some cases, ones made by the plant in response to attack by a pathogen. Many of these advances are still years from commercialization. But regulators must prepare the ground. Monsanto GM soya beans, which use RNA interference to modulate the expression of endogenous genes, are already awaiting a decision from the USDA. The USDA and others need to reconsider how they define andcontrol GM species. If a crop developer uses genetic engineering to delete a discrete segment of a plant genome, how much regulation does that require? Would those same guidelines be appropriate for a crop that expresses half-a-dozen foreign herbicide- and insect-resistance genes, engineered without the use of plant pests? Such questions are particularly important where — as in the United States — GM regulation rests not on the final product of genetic engineering, but on the methods used in the process. The European Commission is tackling the issue, and has commissioned a study into how new plant techniques fall under the rubric of the European Union definition of GM crops. Similarly, the USDA’s Advisory Committee on Biotechnology and 21st Century Agriculture has raised the problem as a point of concern. But the USDA’s proposed changes to its GM regulatory powers, released in draft form in 2008, failed to address challenges posed by new technologies. The USDA’s Kentucky bluegrass ruling comes at a crucial time for agricultural biotechnology. Some estimate that the world must increase the rate of growth in agricultural productivity by 25% per year to meet growing worldwide demand for food and biofuels. Many argue that advances in agricultural biotechnology, some of which may come from GM crops, will be needed to meet this demand. Industry, particularly smaller companies, needs to know how these crops will be regulated before they will invest to develop new techniques. The new breed of GM crops could help gain wider acceptance for the technology, by settling long-standing unease about the use of foreign genes and the inability to target such genes to a specific location in the genome. But it is doubtful that dubious consumers are ready for GM crops to escape regulation altogether. http://www.nature.com/nature/journal/v475/n7356/full/475265b.html
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