Notes

Genetically modified crops provide more benefits than weeds

The wild plants may have the advantage of resistance to herbicides.

Credit Xiao Yang
A common method of genetic modification that makes crops resistant to herbicides has been shown to be superior over rice varieties that are weedy. This finding suggests that the modifications could be detrimental to the environment beyond farm.

Many varieties of crops have been genetically modified to be resistant to glyphosate, an herbicide first marketed under the trade name Roundup. Farmers can eliminate the majority of herbicides from their fields using this glyphosate resistance without damaging their crops.

Glyphosate inhibits growth of plants by inhibiting EPSP synthase (an enzyme involved in the formation of amino acids, and various other molecules). The enzyme can be as large as 35 percent or more of a plant’s total mass. The genetic modification technique employed by Monsanto's Roundup Ready crops, which are based in St Louis (Missouri), typically involves inserting genes in the DNA of the crop to increase EPSP synthase production. The genes typically come from bacteria that cause disease in the plants.

The plant can endure the negative effects of glyphosate due to its extra EPSP-synthase. Biotechnology labs also have tried to make use of genes from plants rather than bacteria to increase EPSP-synthase levels partly to make use of an inconsistency in US law that allows approval by regulators of organisms that have transgenes not that are derived from bacteria.

ラウンドアップ A few studies have explored whether transgenes which confer glyphosate resistance can make plants more competitive in reproduction and survival once they're introduced to weedy or wild relatives by cross-pollination. Norman Ellstrand, a University of California plant geneticist, states that without selection pressure, any type of transgene could be expected to confer disadvantage in wild plants. ラウンドアップ The additional machinery could lower fitness.

But now a study led by Lu Baorong, an ecologist from Fudan University in Shanghai, challenges that view It reveals that the weedy version of the popular rice plant, Oryza sativa has an impressive fitness boost due to the resistance to glyphosate even when glyphosate is not applied.

Their research was published in 1. Lu and his coworkers genetically modified cultivated rice to enhance its EPSP synthase expression and crossed it with a weedy cousin.

The group allowed the offspring of cross-breeding to mix with one another, resulting in second-generation hybrids that are genetically identical to one another, except for the number of copies the gene encoding EPSP synase. As one would expect, hybrids with more copies were more likely to make more tryptophan and had higher enzyme levels than the unmodified hybrids.

ラウンドアップ 畑 Researchers also discovered that transgenics had higher rates, more flowers, and 48-125percent more seeds/plant than nontransgenics.

ラウンドアップ Making the weedy rice more competitive could increase the issues it creates for farmers all over the world whose plots are invaded by the pest, Lu says.

Brian Ford-Lloyd of Brian Ford-Lloyd, a researcher at the University of Birmingham, UK Brian Ford-Lloyd from the University of Birmingham, UK "If the EPSP synthase gene is introduced to wild rice varieties the genetic diversity of their species that was so important to conserve, may be at risk because it could beat out the conventional varieties." "This is one the most obvious instances of extremely plausible negative consequences (of GM crops] upon the environment."

This study also challenges the perception that genetically modified plants with additional copies of their genes are less risky than those that contain microorganisms' genes. Lu claims that the study does not support this view.

ラウンドアップ Researchers believe this finding calls for reconsideration of the regulation for the use of genetically modified plants. Ellstrand claims that some people believe that biosafety regulations could be relaxed since we have two years of genetic engineering. ラウンドアップ ラウンドアップ "But the research indicates that innovative products require an in-depth evaluation."


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