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In the wild, plants can be given herbicide resistance.

Weedy rice can absorb transgenes derived from genetically modified rice by cross-pollinating. Credit: Xiao Yang
One of the most common methods employed to make crops resistant to herbicides was found to offer advantages over weedy forms of rice. This suggests that such genetic modifications could also have the potential to affect wild animals.

A variety of crops have been genetically modified in order to resist the glyphosate. This herbicide was first sold under the tradename Roundup. This glyphosate-resistant crop allows farmers to eliminate the majority of herbicides in their fields without damaging their crops.

Glyphosate prevents plant growth by inhibiting EPSP synthase (an enzyme involved in the formation of amino acids as well as other molecules). This enzyme can be as large as 35% or more of the plant’s total mass. Genetic modification, such as the Roundup Ready crops manufactured by Monsanto in St. Louis, Missouri, involves inserting genes to a crop’s genetic code to boost EPSP production. The genes are typically derived from bacteria that have been infected by plants.

The plant can endure the negative effects of glyphosate due to its extra EPSP-synthase. Biotechnology laboratories are attempting to utilize genes from plants rather than bacteria to increase EPSP synthase. This is partly because the US law allows regulatory approval that allows organisms with transgenes to be recognized as acceptable. Few studies have examined the possibility that transgenes similar to those which confer glyphosate resistance can help plants compete for reproduction and even survival after they’re introduced to wild or weedy cousins by cross-pollination. ラウンドアップ Norman Ellstrand of the University of California, Riverside, explained that the standard assumption was that any transgene will confer disadvantage in nature if there was no selection pressure. This is because any extra machinery could reduce the fitness.

Lu Baorong of Fudan University in Shanghai is now challenging that view. The study demonstrates that glyphosate resistance , even when not applied to the weedy type of rice crop can give a significant health boost.

In their study, published this month in New Phytologist 1, Lu and his coworkers genetically altered the rice cultivar to increase the expression of its own EPSP synthase. They crossed the modified rice with a weedy relative.

The researchers allowed offspring of crossbreeding to crossbreed with one another, resulting in second-generation hybrids that are genetically identical to one another, except for the amount of copies the gene encodes EPSP synase. As one would expect, hybrids that had more copies of the gene had a higher chance to make more tryptophan as well as have greater levels of enzymes over their counterparts that were not modified.

Researchers also discovered that the transgenic hybrids had higher rates of photosynthesis. They also they grew larger flowers and shoots and produced 48-125percent more seeds than the non-transgenic hybrids -without the use of glyphosate.

Lu believes that making rice that is weedy less competitive can make it more difficult for farmers whose plots are affected by pests.

“If the EPSP-synthase gene is introduced into the wild rice species their genetic diversity, which is essential to protect, could be threatened because the genotype with the transgene could outcompete natural species” says Brian Ford-Lloyd, a plant geneticist at the University of Birmingham, UK. “This is one the most obvious instances of extremely plausible negative impacts (of GM crops] upon the environment.”

This study challenges popular perception that genetically modified crops carrying additional copies of their genes are more secure than those containing the genes of microorganisms. Lu claims that the research “shows that this is not always the case”.

ラウンドアップ Some researchers believe this finding calls for a review of future regulation of crops that have been genetically modified. Ellstrand believes that some believe biosafety regulations can be relaxed given the past over two decades of genetic engineering. “But this study has shown that new products need to be evaluated with care.”