Notes

Benefits of genetically modified plants over weeds

In nature, resistance to herbicides could confer advantages to plants.

Credit: Xiao Yang
One common genetic-modification method used to make crops more resistant to herbicides has been shown to have advantages over rice varieties that are weedy. This suggests that such genetic modifications could also have the potential to affect wild animals.

ラウンドアップ There are many kinds of plants are genetically modified to resist the glyphosate. Roundup was the first herbicide that was marketed. Farmers can get rid of weeds in their fields using glyphosate without harming their crops by having this resistance.

Glyphosate slows the growth of plants by stopping EPSP synthase (an enzyme that is involved in the production of specific amino acids and other molecules). This enzyme can be as large as 35% or more of a plant’s total mass. The genetic-modification method, employed for Roundup Ready crops by Monsanto (based in St Louis in Missouri) involves inserting genetic material into a crop to increase EPSP-synthase output. Genes are typically obtained from bacteria that infect crops.

ラウンドアップ This additional EPSP synthase allows the plant to withstand the effects of glyphosate. Biotechnology labs tried to use plant genes to boost EPSP synthase activity. This was done in part to exploit a loophole within US law that allows regulatory approval of organisms containing transgenes that have not been derived from pests caused by bacteria.

There aren't many studies that have examined the possibility that transgenes like glyphosate-resistant genes are able to -- when introduced to wild or weedy plants by cross-pollination -- enhance the competition of plants in reproduction, survival and growth. Norman Ellstrand, a University of California plant geneticist states that in the absence of selection pressure, any kind of transgene would be expected to create disadvantages on wild plants. The added machinery will reduce fitness.

A new study, led by Lu Baorong, an ecologist from Fudan University in Shanghai, challenges that view and shows that a weedy form of the common rice plant, Oryza sativa is given a significant fitness boost from resistance to glyphosate, even when glyphosate isn't used.

Lu and coworkers modified the cultivars of rice to increase its EPSP synthase. https://www.yodobashi.com/product/100000001002109951/ The modified rice was then crossed with a wild-type relative.

The team then permitted the offspring from cross-breeding to cross-breed to create second generation hybrids. They were identical genetically with the exception of the amount of EPSP synthase genes they carried. https://shop.sunday.co.jp/c-3/c-35/c-4500/228935/ As was expected, those with more copies of the gene had higher enzyme levels and produced more amino acid tryptophan compared to their unmodified counterparts.

Researchers also discovered that transgenic hybrids were more photogenic, had more seeds per plant and yielded 48-125 percent higher yields of seeds than the non-transgenic varieties.

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

Brian Ford-Lloyd, a researcher at Brian Ford-Lloyd from the University of Birmingham, UK, says "If the EPSP synthase gene is introduced to wild rice species, their genetic variety, which was really important for conserving, could be endangered because it will surpass the regular varieties." This is among the most evident examples of likely negative effects of GM crop on the environment."

ラウンドアップ The general public believes that genetically engineered crops that have extra copies or microorganisms genes are safer than ones with only the genes of their owners. Lu claims that the research "shows that this is not always the case".

A few researchers believe this discovery needs to be reviewed in light of future regulation of genetically modified crops. Ellstrand believes that biosafety rules can be relaxed since we can benefit from a high degree of comfort from two decades worth of genetic engineering. The study found that any new products need to be evaluated carefully.

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