问答题Genetic researchers have accelerated a plant’s growth by making its cells split fastera 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,” a 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 cellsbut smaller onesand 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.