Notes

The advantages of genetically modified crops over weeds

Wild plants could be given resistance to herbicides.

Credit Xiao Yang
A technique of genetic modification widely used to produce crops that are herbicide-resistant has been shown to confer advantages on a weedy form of rice even in the absence of the herbicide. This suggests that the benefits of this modification could extend beyond the confines of farms into the wild.

Many plants have been genetically engineered to be resistant to glyphosate. This herbicide, initially called Roundup it was released into the market in 1996 under the trade name Roundup. Farmers can get rid of the weeds that grow in their fields with glyphosate, without harming their crops due to this resistance.

Glyphosate acts as an inhibitor of the growth of plants. It blocks an enzyme known EPSP synthase. This enzyme is responsible in the creation of specific amino acids as well as other molecule. These substances can be responsible for as much as 35% of a plant’s mass. The technique of genetic modification employed by Monsanto's Roundup Ready crops, which are based in St Louis (Missouri), typically involves inserting genes in a crop's DNA to increase EPSP synthase's production. ラウンドアップ are typically derived from bacteria that infect plants.

This additional EPSP synthase permits the plant to withstand the effects from glyphosate. Biotechnology labs have also attempted to utilize genes from plants instead of bacteria to boost EPSP-synthase production and, in turn, to take advantage of the loophole in US law that facilitates regulatory approval of organisms carrying transgenes that are not made from bacterial pests.

A few studies have explored whether transgenes like those that confer glyphosate resistant can make plants more competitive in reproductive success and longevity once they are introduced to wild or weedy cousins by cross-pollination. Norman Ellstrand of the University of California, Riverside, explained that the standard assumption was that any transgene could be detrimental to nature if there was no selection pressure. This is due to the fact that any additional machines would reduce the fitness.

However, a new study conducted by Lu Baorong, an ecologist at Fudan University in Shanghai, is challenging that notion It reveals that the weedy form of the common rice crop, Oryza sativa, gets a significant fitness boost from resistance to glyphosate, even when glyphosate isn't used.

Lu and his associates modified cultivars of rice to make more EPSP synthase. They also crossed the modified rice with a weedy-related. Their findings were published in NewPhytologist 1.

The group then allowed hybrid offspring of crossbreds to reproduce with one another, resulting in second-generation hybrids genetically identical to one another with the exception of the number of copies of gene that encodes EPSP synthase. The researchers found that the hybrids that had greater copies of the gene that codes for EPSP synthase expressed more enzymes and also produced more tryptophan which is what we expected.

Researchers also discovered that transgenic plants had higher rates for photosynthesis as well as produced more flowers and produced 48-125% fewer seeds per plant than non-transgenic hybrids. This was despite the fact that glyphosate was not present.

Making weedy rice more competitive can increase the issues it creates for farmers across the globe whose plots are invaded by the pest, Lu says.

Brian Ford-Lloyd, a researcher at the University of Birmingham, UK, says "If the EPSP synthase gene is introduced to wild rice varieties their genetic diversity is crucial in conserving it, could be at risk because it could surpass the regular varieties." "This is one the most evident instances of the highly probable negative consequences [of GM crops] on the natural environment."

The study also challenges the public belief that crops modified genetically with additional copies of their genes are safer than the ones that have genes from microorganisms. Lu claims that the study doesn't support this view.

The finding calls for a reconsideration of the future regulation of the genetically altered crops, scientists suggest. Ellstrand believes that biosafety rules may be relaxed because we are able to enjoy a high level comfort from two decades worth of genetic engineering. The study does not prove that novel products are safe.


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