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Wild plants could be given herbicide resistance.

Weedy rice may absorb transgenes derived from genetically modified rice by cross-pollinating. ラウンドアップ 畑 Credit: Xiao Yang
A common method of genetic modification employed to make crops resistant to herbicides has been shown to be superior over weedy forms of rice. The finding suggests that the benefits of this modifications could extend beyond the confines of farms out into the wild.

A variety of crops have been genetically modified to resist glyphosate, an herbicide first sold under the brand name Roundup. Farmers are able to eliminate weeds in their fields using glyphosate and not harm their crops due to this resistance. Glyphosate is a deterrent to plant growth. It blocks an enzyme known as EPSP synthase. This enzyme is responsible in the production certain amino acids as well as other molecules. These substances can make up as much as 35% of a plant’s mass. The technique of genetic modification used, for instance, in the Roundup Ready crops made by the biotech giant Monsanto located in St Louis, Missouri -usually includes inserting genes into a crop’s genome to increase the production of EPSP synthase. The genes are usually derived from bacteria that cause disease in plants.

The plant is able to endure the negative effects of glyphosate because it has an additional EPSP-synthase. ラウンドアップ Biotechnology labs have also attempted to create EPSP-synthase that is more plant-based than bacteria using genes from plants. This was done to exploit a loophole found in US law which allows regulatory approval for species which aren’t the result of bacteria.

A few studies have looked into the possibility that transgenes that confer glyphosate tolerance may — once they are weedy or become wild relatives by cross-pollinating- increase the plants’ longevity and reproductive. Norman Ellstrand, a University of California plant geneticist, claims that, in the absence of competition, any kind of transgene could be expected to cause disadvantages in wild plants. The added machinery will lower fitness.

Lu Baorong from Fudan University in Shanghai is in the process of challenging this notion. The study shows that resistance to glyphosate even when not applied to an weedy variety of the rice crop can provide a significant health boost.

Lu and his coworkers have genetically altered the cultivated rice species to express the EPSP synthase. Then, they crossed-bred it to an weedy parent.

The team allowed the offspring of cross-breeding to cross-breed with each other to create second-generation hybrids. ラウンドアップ They were identical genetically apart from the number of EPSP synthase genes they carried. The team discovered that the ones with more copies of the gene that encodes EPSP synthase expressed more enzyme and also produced more tryptophan as expected.

The researchers also found that the transgenic hybrids had higher rates of photosynthesis, grew more shoots and flowers and produced 48 to 125 percent more seeds per plant than non-transgenic hybrids — in the absence of the chemical glyphosate.

Lu believes that making weedy, invading rice more competitive might hinder farmers to recover from the harm caused by this bug.

Brian Ford-Lloyd (a UK plant geneticist) says that if the EPSP-synthase gene is introduced into wild rice species, then their genetic diversity which is essential to protect could be at risk. The transgene could outcompete natural species. “This is an example of the most plausible and damaging negative effects of GM crops on the environment.”

The public belief that genetically-modified crops that contain additional copies of their genes are safer is questioned by this study. Lu says that the study “shows that this is not always the case”.

The finding calls for a review of future regulation of genetically modified crops, some researchers say. Ellstrand believes that biosafety regulations may be relaxed because we are able to benefit from a high degree of satisfaction from the two decades of genetic engineering. “But the study demonstrates that new products require an unbiased assessment.”