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Herbicide resistance might confer an advantage on plants in the wild.

Credit: Xiao Yang
One of the most common methods employed to make crops resistant to herbicides has been shown to have advantages over rice varieties that are weedy. The findings suggest that this modification may be able to have positive effects on wild rice varieties and crop varieties.

A variety of cultivars have been genetically modified in order to resist glyphosate. ラウンドアップ This herbicide was first offered under the trade name Roundup. This resistance to glyphosate allows farmers to wipe out most herbicides in their fields without harming their crop.

Glyphosate inhibits plant growth through blocking an enzyme, known as EPSP synthase, which is involved in the production of certain amino acids and other molecules that account for approximately 35% of a plant’s mass. Genetic modification, for instance, the Roundup Ready crops manufactured by Monsanto in St. Louis, Missouri, involves inserting genes into a plant’s genetic code in order to increase EPSP production. ラウンドアップ Genes are usually derived from bacteria that infect the crops.

The extra EPSP synthase lets the plant withstand the effects of glyphosate. Biotechnology labs also have tried to use genes from plants instead of bacteria to boost the production of EPSP synthase, in part to exploit an inconsistency within US law that allows regulatory approval of organisms carrying transgenes not made from bacterial pests.

A few studies have looked into the possibility that transgenes that confer glyphosate tolerance could — after they are weedy or become wild relatives by cross-pollinatingenhance the plant’s survival and reproduce. Norman Ellstrand of University of California Riverside declares, “The conventional expectation is that any transgene found in the wild could cause disadvantages if there is no selection pressure , because the additional machinery may lower the fitness.”

ラウンドアップ A new study, led by Lu Baorong, an ecologist at Fudan University in Shanghai, challenges that view: it shows that the weedy form of the common rice plant, Oryza sativa is given an impressive fitness boost due to glyphosate resistance, even when glyphosate isn’t used.

ラウンドアップ Their research was published in 1. Lu and his colleagues altered the genetics of cultivated rice to boost its EPSP synthase activity and crossed it with a weedy counterpart.

The group allowed the offspring of cross-breeding to mix with each other, resulting in second-generation hybrids genetically identical to each other , with the exception of the number of copies the gene encoding EPSP synase. ラウンドアップ The team found that those who had more than one copy of the gene encoding EPSP synthase expressed more enzymes and produced more tryptophan, as expected.

Researchers also discovered that the transgenic hybrids had greater rates of photosynthesis, they grew larger flowers and shoots and produced 48-125percent more seeds than the non-transgenic hybridswithout the use of the chemical glyphosate.

ラウンドアップ Lu says that making weedy grains more competitive may cause more problems to farmers all over the world whose crops are affected by the insect.

ラウンドアップ Brian Ford-Lloyd (a UK plant geneticist) says that if the EPSP-synthase genes gets into wild rice species, their genetic diversity, which is vital to preserve could be endangered. The transgene will surpass the regular species. This is one of the clearest examples of extremely plausible harmful effects [of GM crop] on the environment.”

The study also challenges the perception that genetically modified crops that carry extra copies of their own genes are safer than the ones that have the genes of microorganisms. “Our study shows that this is not necessarily the case,” says Lu.

Researchers believe this discovery calls for a reconsideration of the regulation for genetically modified crops. “Some individuals are saying that biosafety regulations are relaxed because we have an extremely high level of satisfaction with two years of genetic engineering” Ellstrand says. “But the research shows that novel products require an in-depth evaluation.”