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Herbicide resistance could give plants an advantage in the wild.

ラウンドアップ Credit Xiao Yang
A genetic-modification technique used widely to make crops herbicide resistant has been shown to provide advantages to an invasive form of rice even in the absence of the herbicide. This suggests that this genetic modification may also have potential to affect wild animals.

Many cultivars are genetically altered in order to ward off the effects of glyphosate. The herbicide was initially sold under the tradename Roundup. This glyphosate resistance enables farmers to eradicate the majority of herbicides in their fields without causing damage to their crop.

Glyphosate slows the growth of plants by blocking EPSP synthase (an enzyme that plays a role in the creation of certain amino acids as well as various other molecules). This enzyme can make up as much as 35 percent or more of a plant’s total mass. Genetic modification, such as the Roundup Ready crops manufactured by Monsanto in St. Louis, Missouri, involves inserting genes into the genetic code to boost EPSP production. The genes typically come from bacteria that are infected with plants.

The plant is able to withstand the effects caused by glyphosate due to its additional EPSP-synthase. Biotechnology labs have also attempted to make use of the genes of plants to boost EPSP-synthase levels, in part to take advantage of a loophole in the American system that permits regulatory approval of transgenes not derived bacterial pests.

A few studies have looked into whether transgenes such as those that confer resistance to glyphosate are able to — once they become wild or weedy relatives by cross-pollination -make plants more competitive in terms of survival and reproduction. Norman Ellstrand of University of California Riverside declares, “The conventional expectation is that any transgene in the wild will confer disadvantage if there’s no pressure to select because the additional machinery may lower the fitness.”

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

The study was published in 1. Lu and his collaborators altered the genetics of cultivated rice to increase its EPSP synthase expression , and then crossed it with a weedy cousin.

The researchers then allowed the offspring of cross-breeding to be bred with one another to create second-generation hybrids. ラウンドアップ They were genetically identical, with the exception of the copy count and number of EPSP synthase gene. The team found that those with greater copies of the gene that codes for EPSP synthase expressed more enzyme and produced more tryptophan, as expected.

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

Lu believes making weedy, invading rice more competitive might make it more difficult for farmers to recoup the damage caused by this pest.

Brian Ford-Lloyd, an UK plant geneticist and states, “If the EPSP synthase gene is introduced into wild rice varieties, their genetic diversity would be at risk, which is important because the genotype with transgene outcompetes the normal species.” This is one of the clearest examples of extremely plausible harmful effects [of GM crop on the environment.”

The public has a perception that genetically engineered crops that have additional copies of microorganisms’ genes are less risky than those with only their own genes. Lu claims that the research “shows that this is not always true”. The finding calls for a reconsideration of the future regulation of genetically modified crops, some researchers claim. “Some individuals are claiming that biosafety regulations can be relaxed since we’ve achieved an extremely high level of satisfaction in the last two years of genetic engineering” says Ellstrand. “But the research shows that the new technologies require careful assessment.”