Benefits of genetically modified crops over the weeds


Wild plants might be resistant to herbicides.

Credit Xiao Yang
A method of genetic modification used extensively to create crops that are resistant to herbicides has been shown to give advantages to a weedy form of rice, even in the absence of the herbicide. This suggests that the effects of such modifications could extend beyond farms and into the wild.

Many crops are genetically modified in order to ward off the glyphosate. This herbicide was first available under the trade name Roundup. This glyphosate-resistant crop allows farmers to eradicate the majority of weeds from the fields without harming their crops.

Glyphosate inhibits an enzyme known as EPSP synthase that is responsible for the creation of specific amino acids and various other molecules. It also can hinder plant growth.https://search.kakaku.com/%8F%9C%91%90%8D%DC%20%83%89%83E%83%93%83h%83A%83b%83v%83%7D%83b%83N%83X%83%8D%81%5B%83h/ The genetic modification method employed for Roundup Ready crops by Monsanto (based in St Louis in Missouri) is the process of inserting genes into a crop to increase EPSP-synthase output. These genes usually come from bacteria that has infected the plant.

The addition of EPSP synase allows for the plant to resist the harmful effects of glyphosate. Biotechnology labs have also attempted to create EPSP-synthase that is more plant-based than bacteria, using genes derived from plants. This was done to exploit the loophole in US law, which permits regulatory approval for organisms that are not derived from bacteria.

Few studies have investigated whether transgenes such glyphosate-resistant genes can -- once introduced to weedy or wild plants by cross-pollination -- enhance the competition of plants in reproduction, survival and growth. Norman Ellstrand of the University of California, Riverside, stated that the conventional expectation was that any transgene could cause disadvantage in nature when there was no selection pressure. This is because any extra machinery would lower the fitness.

Lu Baorong, an ecologist from Fudan University in Shanghai has revised that opinion. He has discovered that glyphosate resistance provides an impressive fitness boost to a weedy variant of the standard rice crop Oryza Sativa.

Lu and his coworkers have genetically altered the cultivated rice species to express its EPSP synthase, and then crossed it with a weedy parent.

The researchers then allowed offspring cross-bred to breed with one another, resulting in second-generation hybrids that were genetically identical to their parents except for the number of copies of the gene that encodes EPSP synthase. The hybrids that had more copies of the gene had a higher chance to produce more tryptophan and have higher enzyme levels over their counterparts that were not modified.

Researchers also found that transgenic plants had higher rates for photosynthesis, 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.

Lu believes that making weedy rice less competitive could make it more difficult for farmers who have their land affected by pests.

"If the EPSP-synthase gene gets into the wild rice species their genetic diversity, which is vital to preserve may be at risk as the transgene's genotype would outcompete the normal species," Brian Ford-Lloyd who is a plant geneticist at the University of Birmingham, UK. This is among the clearest examples of extremely plausible negative effects [of GM crop on the environment."

The general public believes that genetically engineered crops with more copies or microorganisms' genes are more secure than those containing only their own genes.http://www.ihs-agri.jp/nouyaku/hatasaku-josou/hatasaku-josou-keiyou/josou101090010301.html Lu states that "our study is not proving that this is the case."

Some researchers believe this finding requires a review of the future regulation of genetically modified crops. Ellstrand claims that some people think that biosafety rules can be relaxed because we've had two years of genetic engineering. "But this study has shown that the new technologies still require careful analysis."