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Herbicide resistance may provide advantages to plants in the wild.

Credit: Xiao Yang
It has been demonstrated that a technique for genetic modification, which is widely used to make crops resistant to herbicides, can provide advantages to an invasive variety of rice. ラウンドアップ This finding suggests that these changes could be detrimental to the natural environment beyond farms.

ラウンドアップ A variety of crops have been genetically modified to make them immune to Roundup herbicide glyphosate. The resistance to glyphosate permits farmers to get rid of herbicides, without causing damage to their crop.

Glyphosate is an inhibitor of plant growth. It blocks an enzyme known EPSP synthase. This enzyme is responsible for the production of certain amino acids and other molecules. These compounds could make up as much as 35% of the plant’s mass. The genetic-modification method, employed in Roundup Ready crops by Monsanto (based in St Louis in Missouri) is the process of inserting genes in a plant to boost EPSP-synthase output. Genes usually come from bacteria that infect plants.

This extra EPSP synthase allows the plant to withstand the effects from glyphosate. Biotechnology labs are also looking to use genes that come from plants instead of bacteria to increase EPSP synthase. This is due to the fact that the US law allows approval by the regulatory authorities to allow organisms that have transgenes to be accepted.

ラウンドアップ Few studies have investigated whether transgenes such glyphosate-resistant genes can — once introduced to weedy or wild plants through cross-pollination make these plants more competitive in survival, reproduction and growth. Norman Ellstrand, a University of California plant geneticist says that without selection pressure, any type of transgene is likely to create disadvantages in wild plants. The added machinery will decrease 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 could provide a substantial health boost.

In the study published this month in New Phytologist 1, Lu and his colleagues modified the genetics of the rice cultivar to increase the expression of its own EPSP synthase. ラウンドアップ They also crossed-bred the modified rice with a weedy cousin.

The researchers then allowed offspring cross-bred to breed with one another, creating second generation hybrids that were genetically identical to their parents, except for how many duplicates of the gene that codes for EPSP synthase. The team discovered that the ones who had more copies of the gene encoding EPSP synthase expressed more enzymes and produced more tryptophan, as expected.

Researchers also found that transgenics have higher rates, had more flowers and 48 to 125 percent more seeds per plant than nontransgenics.

Lu states that making the weedy grain more competitive could create more difficulties to farmers around the world who have crops affected by the insect.

Brian Ford-Lloyd is Brian Ford-Lloyd is a UK plant geneticist and says, “If the EPSP synthase gene becomes present in wild rice species, their genetic diversity would be endangered, which is significant because the genotype with transgene is superior to the natural species.” This is one of the most evident examples of plausible harmful effects [of GM crop on the environment.”

ラウンドアップ The study also challenges the public belief that crops modified genetically carrying extra copies of their own genes are less dangerous than those that contain the genes of microorganisms. Lu states that “our study is not proving that this is the case.”

The findings call for a rethinking of future regulation of the genetically altered crops, scientists say. Ellstrand thinks that biosafety regulations can be relaxed since we can have a great level of satisfaction from the two decades of genetic engineering. “But the study demonstrates that novel products still need an unbiased evaluation.”