Genetically-modified plants do not turn into rampant superweeds 鈥� they simply wither and die like any other crop plant, according to results from the world鈥檚 longest-running experiment on GM crops.
But reassuring as this appears, it may not apply to all GM crops.
Ten years ago, Mike Crawley and his colleagues at Imperial College London, planted GM maize, sugar beet and potatoes alongside their natural counterparts.
Advertisement
Since then, all the GM plants have died out. The only survivors are ordinary potatoes. 鈥淭here was no case where GM plants survived significantly longer than conventional plants,鈥� says Crawley.
The GM plants were not any more invasive than their orthodox brethren either. Differing climates made no difference to the results, as tests took place from the southern warmth of Cornwall and Berkshire to the wilds of Sutherland in Scotland.
Seeds of doubt
Crawley stresses, however, that his reassurances only apply to the specific crops used in the experiment. 鈥淵ou can鈥檛 say all GM crops are safe,鈥� he says.
The GM oilseed rape, maize and sugar beet had resistance to one of two weedkillers, glyphosate and glufosinate. Genes in the potatoes produced bacterial or plant toxins as protection against insect pests.
鈥淎ll we can say from our experiment is don鈥檛 worry about this combination of crops and [genes],鈥� says Crawley. 鈥淭here鈥檚 no theory that allows you to work out invasiveness in advance,鈥� he says.
鈥淚f you insert genes different to these, you鈥檇 have to test them experimentally,鈥� says Crawley, whose results are published in Nature.
If plants were resistant to viruses that also affect wild plants and insects, for example, they might be more invasive, he says. So too might plants engineered to grow faster or tolerate shade.
More at: Nature (vol 409, p682)
