Notes

Genetically modified crops pass benefits to Weeds

Wild plants could be given resistance to herbicides.

Credit Xiao Yang
A well-known method of genetic modification of crops that make them herbicide-resistant has been found to give advantages to weedy varieties rice even when the herbicide is not present. This suggests that the genetic modification could also have potential to affect wild animals.

A variety of plants have been genetically engineered to be resistant to glyphosate. This herbicide, originally called Roundup and then introduced into the market in 1996 under the tradename Roundup. Farmers are able to eliminate weeds from their fields with this glyphosate resistance , without damaging their crops.

Glyphosate inhibits growth of plants by stopping EPSP synthase (an enzyme that is involved in the production of specific amino acids and various other molecules). This enzyme can be as large as 35 percent or more of a plant's total mass. https://shopping.geocities.jp/truetools/category/roundup_maxload/ The genetic modification method used in Roundup Ready crops by Monsanto (based in St Louis in Missouri), involves inserting genes in a plant to boost EPSP-synthase output. The genes typically come from bacteria that infect the plants.

The addition of EPSP synase allows for the plant to resist the harmful effects of glyphosate. ラウンドアップ Biotechnology labs also have tried to utilize genes from plants rather than bacteria to boost EPSP-synthase production and, in turn, to take advantage of an inconsistency in US law that permits the approval of regulatory agencies for organisms that carry transgenes that are not derived from bacterial pests.

A few studies have looked into whether transgenes that confer glyphosate tolerance could -- after they become weedy , or wild relatives via cross-pollinating -enhance the plant's survival and reproduce. Norman Ellstrand of the University of California, Riverside, said that the traditional expectation was that any transgene could confer disadvantage in nature if there was no pressure to select. This is because extra machinery would lower the fitness.

Lu Baorong (an ecologist at Fudan University, Shanghai) has now questioned that opinion. ラウンドアップ It has proven that resistance to glyphosate can provide an impressive fitness boost to the weedy rice crop known as Oryza Sativa even when not used.

ラウンドアップ Lu and colleagues modified cultivars of rice to improve its EPSP synthase. The modified rice was crossed with a wild relative.

The researchers then allowed offspring to crossbreed with one another, resulting in second generation hybrids which are genetically similar to their parents, except for the number of duplicates of the gene that codes for EPSP synthase. Likely, the ones who had more copies expressed higher levels of the enzyme and produced more amino acids tryptophan than their unmodified counterparts.

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

Lu believes that making weedy invading rice more competitive might make it more difficult for farmers to repair the damage caused by this pest.

"If the EPSP-synthase gene gets into the wild rice plant, their genetic diversity, which is really essential to protect may be at risk as the transgene's genetic make-up will outcompete the normal species," says Brian Ford-Lloyd, a plant geneticist at the University of Birmingham, UK. "This is among the clearest examples of highly plausible negative effects [of GM crops on the environment."

The study also challenges the idea that crops with genetically modified genes containing additional copies of their genes are more safe than those containing microorganism genes. https://search.yahoo.co.jp/image/search?rkf=2&ei=UTF-8&gdr=1&fr=wsr_gs&p=%E3%83%A9%E3%82%A6%E3%83%B3%E3%83%89%E3%82%A2%E3%83%83%E3%83%97 Lu says that the study "shows that this is not always true".

Researchers believe this discovery requires reconsideration of the regulation for the use of genetically modified plants. "Some people are now claiming that biosafety regulations are relaxed because we have an incredibly high level of confidence with two years of genetic engineering" says Ellstrand. The study does not prove that the new products are secure.


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