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Wild plants could be given resistance to herbicides.

Credit: Xiao Yang
One of the most common methods used to make crops more resistant to herbicides has been shown to have advantages over weedy forms of rice. This suggests that such genetic modification could also have potential to have an impact on wild animals.

ラウンドアップ Many varieties of crops have been genetically modified to be intolerant to the herbicide glyphosate. It was initially marketed under the brand name Roundup. Farmers are able to eliminate weeds from their fields with this glyphosate resistance , without causing damage to their crops.

Glyphosate inhibits growth of plants by stopping EPSP synthase (an enzyme that plays a role in the production of specific amino acids and various other molecules). ラウンドアップ The enzyme can comprise as much as 35% or more of the plant’s total mass. The genetic modification method used in Roundup Ready crops by Monsanto (based in St Louis in Missouri) is the process of inserting genes into the crop to increase EPSP-synthase output. ラウンドアップ ラウンドアップ The genes are typically derived from bacteria that have been infected by plants.

The added EPSP synthase allows the plant to be resistant to the effects of glyphosate. Biotechnology labs have also tried to create EPSP synthase with more plant-based components than bacteria, using genes derived that come from plants. This was partly done to exploit the loophole in US law, which permits regulatory approval for species which aren’t the result of bacteria or parasites.

Few studies have examined the possibility that transgenes similar to those that confer resistance to glyphosate make plants more competitive for reproduction and even survival after they are introduced to weedy or wild relatives through cross-pollination. ラウンドアップ Norman Ellstrand of the University of California, Riverside, stated that the conventional expectation was that any transgene would be detrimental to nature if there was no selection pressure. This is due to the fact that any additional machines would reduce the fitness.

Lu Baorong of Fudan University in Shanghai is now challenging that view. The study shows that resistance to glyphosate even when it is not applied to the weedy varieties of the rice crop could provide a substantial health boost.

ラウンドアップ In the study published this month in New Phytologist 1, Lu and his colleagues genetically modified the rice cultivar to enhance its own EPSP synthase. They crossed the altered rice with a weedy ancestor.

The team then allowed the offspring of cross-breeding to be bred together to produce second-generation hybrids. ラウンドアップ They were genetically identical, with the exception of the number and copy count of EPSP synthase gene. As expected, the ones with more copies had greater levels of enzymes and produced an increased amount of amino acid tryptophan when compared to the unmodified counterparts.

Researchers also discovered that transgenic hybrids produced 48-125percent more seeds per plant. They also had higher photosynthesis rates and produced more shoots than those that were not transgenic.

Lu believes that making rice that is weedy less competitive might make it harder for farmers who have their plots invaded by pests.

“If the EPSP-synthase genes are introduced into the wild rice species, their genetic diversity, which is essential to protect is at risk because the transgene’s genetic make-up could outcompete normal species,” says Brian Ford-Lloyd an expert in plant genetics at the University of Birmingham, UK. ラウンドアップ “This is one of the most clear examples of extremely plausible damaging effects [of GM crops on the environment.”

The public believes that genetically modified plants containing more replicas of their own genes than microorganisms are more safe. ラウンドアップ This belief is not supported by this study. Lu states that the study “shows that this isn’t always the case”.

The findings call for a review of future regulations for the genetically altered crops, scientists claim. “Some individuals are claiming that biosafety regulation can be relaxed because we have an incredibly high level of confidence with the two years of genetic engineering” says Ellstrand. “But the research shows that the new technologies require careful examination.”