Notes

Genetically modified crops pass advantages to weeds

Wild plants could be treated with herbicides.

ラウンドアップ is able to take on transgenes from genetically modified crops through cross-pollination. Credit: Xiao Yang
The use of genetic modification to make crops resistant to herbicides has been extensively utilized to provide advantages to species of rice that are weedy. This suggests that the benefits of such modifications could extend beyond the confines of farms into the wild.

Many cultivars have been genetically altered so that they can ward off the effects of glyphosate. The herbicide was initially offered under the trade name Roundup. This glyphosate resistance enables farmers to eliminate the majority of herbicides in their fields without damaging their crop.

Glyphosate is a plant-killer by inhibiting EPSP synase which is an enzyme that plays a role in the production amino acids as well as other chemicals that comprise about 35% of plant mass. The genetic-modification technique -- used, for instance, in the Roundup Ready crops made by the biotechnology giant Monsanto which is headquartered in St Louis, Missouri -generally includes inserting genes into the crop's genome to increase the production of EPSP synthase. The genes are typically derived from bacteria that have been infected by plants.

ラウンドアップ is able to withstand the effects caused by glyphosate due to its additional EPSP-synthase. ラウンドアップ 互換 have tried to create EPSP synthase with more plant-based components than bacteria using genes from plants. This was used to take advantage of an inconsistency found in US law, which permits the approval of regulatory authorities for organisms that aren't derived from bacteria or parasites.

A few studies have looked into the possibility that transgenes that confer tolerance could -- after they become weedy or wild relatives by cross-pollinatingcan boost the plant's survival and reproduction. Norman Ellstrand is a University of California Riverside plant geneticist. "The assumption is that any transgene can cause disadvantage in the wild in the absence of pressure to select, because it would reduce fitness," Ellstrand said.

Lu Baorong (an ecologist at Fudan University, Shanghai) has now questioned that opinion. It has proven that glyphosate resistance can give significant benefits to fitness for the weedy rice crop known as Oryza sativa even when not in use.

Their study was published in 1. Lu and his colleagues genetically modified cultivated rice to increase its EPSP synthase expression , and then crossed it with a weedy cousin.

The researchers allowed offspring of crossbreeding to crossbreed with each other, resulting in second-generation hybrids genetically identical to each other except for the number of copies the gene encodes EPSP synase. As one would expect, the more copies produced higher levels of enzyme, and also more tryptophan, than the unmodified counterparts.

Researchers also discovered that transgenics had higher rates, had more flowers and 48-125percent more seeds/plant than nontransgenics.

Lu believes making weedy, aggressive rice more competitive could make it more difficult for farmers to recover from the harm caused by this bug.

Brian Ford-Lloyd, an UK plant geneticist who states, "If the EPSP synthase gene becomes present in wild rice species their genetic diversity could be at risk, which is important because the genotype with transgene has a higher level of competition than the standard species." "This is a clear illustration of the extremely plausible detrimental effects [of GM plants] on our environment."

The popular belief that genetically modified crops that contain additional copies of their genes are safer is challenged by this study. Lu says that "our study does not prove this to be the case."

The research results call for a reconsideration of the future regulations for genetically modified crops, some scientists say. Ellstrand says that some people believe biosafety regulations can be relaxed given the past two years of genetic engineering. The study does not prove that the new products are secure.


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