Notes

Genetically modified crops pass advantages to weeds

Herbicide resistance might provide advantages to plants in the wild.

Weedy rice can pick up transgenes from genetically modified crop rice by cross-pollinating. Credit: Xiao Yang
It has been established that a technique for genetic modification that is used extensively to make crops resistant to herbicides, gives advantages to an invasive variety of rice. ラウンドアップ ラウンドアップ 時間 These findings suggest that such modifications could have a wide variety of impacts that extend beyond farms, and possibly out into the wild.

A wide range of crops have been modified genetically so that they become immune to Roundup herbicide glyphosate. The resistance to glyphosate allows farmers to eliminate plants without doing any harm to their crop.

Glyphosate prevents plant growth by inhibiting EPSP synthase (an enzyme involved in the formation of amino acids, and various other molecules). The enzyme can make up as much as 35 percent or more of the plant's total mass. The genetic-modification technique is used for instance, in Roundup Ready plants made by Monsanto Biotechnology Inc., a biotech firm located in St Louis, Missouri. It involves inserting genes into the genome of a plant to boost EPSP synthase-synthase production. The genes typically come from bacteria that has infected the plant.

The additional EPSP synthase allows the plant to resist the effects of glyphosate. Biotechnology labs have also attempted to use plants' genes to boost EPSP-synthase levels, in part to take advantage of a loophole in the American system which permits the approval of regulatory authorities of transgenes which are not derived from by bacterial pests.

Few studies have examined whether transgenes like those that confer resistance to glyphosate increase the competitiveness of plants for reproduction and even survival after they're introduced to wild or weedy cousins by cross-pollination. "The common belief is that any transgene could cause disadvantage in the wild in absence of any selection pressure because the extra machinery would lower the fitness," says Norman Ellstrand, a plant geneticist at the University of California in Riverside.

Lu Baorong is an ecologist in Fudan University Shanghai. His study shows that glyphosate resistance is a major fitness benefit, even if it's not used.

ラウンドアップ The study was published in 1. Lu and his colleagues have genetically modified rice to boost its EPSP synthase activity and crossed it with a weedy relative.

The team allowed the offspring of cross-breeding to cross-breed with each other to create second generation hybrids. They were identical genetically with the exception of the amount of EPSP synthase genes they carried. As one would expect, the more copies resulted in higher levels of enzyme, and also more tryptophan, than their unmodified counterparts.

Researchers also found that transgenics have higher rates, more flowers, and 48 to 125 percent more seeds per plant than nontransgenics.

Lu states that making weedy crops more competitive can create more difficulties to farmers all over the world who have crops infected by the insect.

Brian Ford-Lloyd is an UK plant geneticist and says, "If the EPSP synthase gene gets in the wild rice species, their genetic diversity would be endangered, which is important because the genotype with transgene outcompetes the normal species." ラウンドアップ This is among the clearest examples of extremely likely negative effects of GM crop] on the environment."

The study also challenges the perception that genetically modified crops carrying extra copies of their genes are safer than the ones that have genes from microorganisms. Lu says, "Our study shows this is not always the case."

The research results call for a review of future regulations for genetically modified crops, some researchers say. Ellstrand says that some people believe that biosafety regulations could be relaxed since we have over two decades of genetic engineering. ラウンドアップ The study showed that new products should be evaluated carefully.


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