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Wild plants might be resistant to herbicides.ラウンドアップマックスロード/ Weedy rice can take on transgenes from genetically modified crop rice through cross-pollination. ラウンドアップ Credit: Xiao Yang
A common method of genetic modification used to make crops more resistant to herbicides was shown to offer advantages over rice varieties that are weedy. This suggests that the modifications could be detrimental to the environment beyond farm.

ラウンドアップ Many crop varieties have been genetically modified in order to ward off the glyphosate. The herbicide was initially offered under the trade name Roundup. Farmers are able to eliminate the weeds that grow in their fields with glyphosate without harming their crops because of this resistance.

Glyphosate inhibits growth of plants by stopping EPSP synthase (an enzyme involved in the production of specific amino acids and various other molecules). This enzyme can be as large as 35 percent or more of a plant’s total mass. The genetic-modification technique — employed, for example in Roundup Ready crops made by the biotechnology giant Monsanto, based in St Louis, Missouri -usually involves inserting genes into the crop’s genome to boost EPSP-synthase production. Genes are typically derived from bacteria that cause disease in plants. The plant can withstand the effects caused by glyphosate since it has an extra EPSP-synthase. Biotechnology labs also tried to use plants’ genes to boost EPSP-synthase levels, in part to exploit an American loophole that allows for regulatory approval of transgenes which are not derived from bacterial pests.

Few studies have tested whether transgenes , such as those that confer resistance to glyphosate are able to — once they become weedy or wild relatives through cross-pollination, make plants more competitive in terms of survival and reproduction. Norman Ellstrand of the University of California, Riverside, explained that the standard assumption was that any transgene could confer disadvantage in nature if there was no selection pressure. This is because extra machinery would lower the effectiveness of.

But now a study led by Lu Baorong, an ecologist at Fudan University in Shanghai, is challenging that notion and shows that the weedy variant of the standard rice crop, Oryza sativa has an impressive fitness boost due to glyphosate resistance, even when glyphosate isn’t applied.

In the study published this month in New Phytologist 1, Lu and his coworkers genetically altered the cultivated rice species to overexpress the species’ own EPSP synthase. They crossed the modified rice with a weedy ancestor.

The team then allowed breeding offspring that were cross-bred together to produce second-generation hybrids. These were genetically identical with the exception of the number and copy count of the EPSP synthase gene. As one would expect, hybrids with more copies were more likely to make more tryptophan as well as have more enzyme levels over their counterparts that were not modified.

Researchers also found that transgenic hybrids produced between 48 to 125 percent more seeds per plant, had more photosynthesis, and had more shoots than those that were not transgenic.

Making the weedy rice more competitive may exacerbate the problems it causes for farmers all over the world who’s plots are infested by pests, Lu says.

ラウンドアップ ラウンドアップ 持続期間 Brian Ford-Lloyd (a UK plant geneticist) states that if the EPSP synthase gene is introduced into wild rice species, then their genetic diversity, which is vital to preserve could be at risk. ラウンドアップ The transgene could surpass the regular species. This is one of the most evident examples of plausible harmful effects [of GM crop on the environment.”

ラウンドアップ The belief of the public that genetically modified crops containing additional copies of their genes are more secure is disproved by this research. Lu declares that “our study doesn’t prove that this is the case.”

According to some scientists, the finding suggests that future regulation of genetically engineered crops needs to be reviewed. Ellstrand claims that “some people are now of the opinion that biosafety regulations could be relaxed since we have a the most comfort with genetic engineering for the past two decades.” “But the study proved that novel products still require careful evaluation.”