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Let us spray New Scientist 4 Apr 98

CROPS can now be genetically engineered to resist herbicides without the danger of creating superweeds. Farmers want crops that are engineered to resist herbicides so they can tise theni liberally to kill weeds. But resistance to the weedkiller could be spread by pollen. Now researchers have engineered resistaiice to glypilosate, a common weedkiller, in a tobacco plant so that the resistance cannot be spread by pollen to other plants (Nature Biotechnology, vol 16, p 347). The trick was to insert the resistance gene into the plants' chloroplasts. Tile DNA from chloroplasts is only spread through female plants-pollen conies from males. Glyphosate is a herbicide that kills plants by blocking the creation of an enzyme called EPSP synthase, which the plant needs to synthesise amino acids. But crops and weeds are killed by glyphosate Over the past few years, Monsanto liis marketed soya beans and cotton which have been engineered to resist glyphosate. But environmentalists are concerned that the resistance could spread to wild relatives of some crops, creating super weeds that would not be easy to control. The concern is greatest for cereal crops, which can interbreed with some grassy weeds. Henry Daniell and his colleagues at Auburn University in Auburn, Alabama, u tackled the problem by inserting the resistance gene, taken from a petunia, into the plant's choloroplasts. Chloroplasts are the structures which manufacture chlorophyll. They have their own genome, and the chloroplasts are passed down only through the female plant so that pollen cannot spread the resistance. Daniell constructed a resistance gene which would bind only to a piece of DNA in the chloroplasts, and used a gene gun to insert it. The altered chloroplasts manufactured large amounts of EPSP synthase, overwhelming the glyphosate's effect. If the technique can be applied to crops, it removes worries about crops interbreeding with weeds, and makes it easier for seed companies to win approval for the products. Ingo Potrykus, a plant developmental biologist at the Institute of Plant Sciences in Zurich, has his doubts. He says Daniell's technique will be much harder to implement in important cereal crops than in tobacco. "Every big company would like to have this for cereal. Nobody has so far been able to achieve it," he says. But environmentalists also have reservations. "This is a teclitiology that is being used to perpetuate a dependence on herbicides. It is not being used to help farmers get away from herbicides," says Jane Rissler, a scientist with the Union of Concerned Scientists in Washington, DC. Kurt Kleiner, Washington DC

Better safe than sorry New Scientist 4 Apr 98

A NEWLY cautious approach to pesticide safety, proposed by the US Environmental Protection Agency (EPA), has won the backing of the agency's Science Advisory Panel. The panel last week approved a plan that will reduce the amounts of pesticide to which people can be exposed by an additional tenfold safety factor. But pesticide manufacturers complain that the rules are too stringent. To calculate the maximum allowable residues of pesticide that can be left on crops, the EPA has previously taken the minimum level shown in animal experiments to cause adverse health effects, and divided this by 100. But the 1996 Food Quality Protection Act demanded the additional safety factor if there was a danger tilat children might be especially vulnerable to a pesticide's toxic effects. In drafting new regulations, the ElA decided that this extra safety factor must be applied unless it has been proven that a pesticide is not especially toxic to children. This broad interpretation of the 1996 Act angered the American Crop Protection Association, an industry group based in Washington DC. It wanted the extra safety factor to be applied only when there was firm evidence that children might be particularly badly affected. "Caution should be taken to avoid unrea sonable worst-case scenarios," it told the EPA. But Ernest McConnell, a veterinary pathologist and toxicologist at North Carolina State Univer sity in Raleigh, who chairs the EPA's science panel, says that its members decided that a cautious approach was best. "We thought the EPA was using good science and working in the right direc tion," he says. The panel's decision is bad news for Rh6ne-Poulenc Ag Company of Research Triangle Park in North Carolina, the manufacturer of a herbicide called bromoxynil, and Stoneville Pedigreed Seed of Memphis, which markets a variety of cotton engineered to resist high levels of bromoxynil. The EPA has refused to extend a permit that allowed bromoxynil to be used on cotton, citing the new safety factor (This Week, 10 January, p 12). Both companies are appealing against the decision. Kurt Klainer

Named and Shamed New Scientist 4 Apr 98

LEADING biotechnology companies that failed to stick to agreed plans for field experiments with genetically engineered plants have liad tileir knuckles rapped by Britain's gene police. Though not fined, the culprits have been iiaiiied and some liave been forced to rip up the plots. The Advisory Committee on Releases to the Environment (ACRE), which advises the British government on the safety of releasing genetically engineered organisms, last week publicised a rogues'gallery of companies and research labs that have breached the terms of their consents to carry out field experiments. The companies are Monsanto of St Louis, Missouri, the world's largest agricultural bictech firm; Plant Genetic Systems of Ghent in Belgium; AgrEvo of Frankfurt, Gerniany; atid Nickerson Biocem of Cambri(,ige. The oilier miscreants are tlie Scottish Crop Research Institute near Dundee and the National Institute of Agricultural Botany in Cambridge. "This should help to show that tlie government is not acting like a doormat," says John Beringer, a microbiologist at the University of Bristol, who chairs ACRE. "I'm all for naming and shaming and this is worth many time the fines.." Anyone planning to grow an experimental plot of genetically-engineered plants in Britain must first put detailed proposals to ACRE. The conimittee recommends whether hie government should issue a consent. The breaches highlighted by ACRE were uncovered by the Health and Safety Executive (HSE). Most concern failures to stick to procedures designed to prevent eligiiieered crops straying outside their plots or hybridising with neighbouring plants. Nickerson and Monsanto both allowed crops to grow much nearer to unmodified plants than agreed. In February, Monsanto was told to destroy a plot of oilseed rape tolerant to the herbicide glyphosate. The crop was surrounded by a buffer zone 27 metres across, instead of 50 metres. Nickerson, meanwhile, grew unmod if ied oilseed rape just 2.5 metres from a traiisgenic variety carrying extra genes for phytase, an enzyme that improves the uptake of phosphate by cattle eating the crop. The agreed buffer zone was 400 metres. Nickerson had to harvest and bury the seeds and has been banned from growing rape in a plot of some 64 hectares for three years. Monsanto and Nickerson say that the errors arose from misunderstandings by the contractors who carried out the trials. But they accept responsibility. "It's completely inexcusable, and we've done everything we can to avoid it liappening again," says Tina Barsby, director of Nickerson Biocem-Research labs outside industry also broke the rules. The Scottish Crop Research Institute, for instance, Surrounded a plot of engineered potatoes with beans, rather than cereals-which would make any escaped potato plants difficult to spot. Kath Heywood of the HSE, who is in charge of policing consents to release engineered organisms, says that 139 consetns are valid at present. Inspectors checked out 28 last year, she says, which involved visits to 70 different sites. That leaves pressure groups wondering whether there are further breaches still waiting to be discovered. Sue Mayer of Gene Watch asks: "Is it the tip of the iceberg?" Andy Coghlan