Notes

Genetically modified crops offer more benefits than herbicides

The wild plants could have an herbicide resistance advantage.

Credit Xiao Yang
It has been demonstrated that a genetic-modification technique that is used extensively to make crops resistant to herbicides, confers advantages on a weedy variety of rice. This indicates that the modifications could be detrimental to the environment beyond farms.

Many varieties of crops are genetically modified to be intolerant to glyphosate, a herbicide that was first marketed under the trade name Roundup. Farmers are able to eliminate the weeds that grow in their fields by using this glyphosate resistance without causing damage to their crops.

ラウンドアップ Glyphosate acts as an inhibitor of plant growth. ラウンドアップ It inhibits an enzyme called EPSP synthase. This enzyme is responsible in the production certain amino acids as well as other molecule. These compounds can make up as much as 35% of the plant's mass. ラウンドアップ The genetic modification technique employed by Monsanto's Roundup Ready crops, which are located in St Louis (Missouri), generally involves inserting genes into the DNA of a plant to boost EPSP synthase's production. Genes are typically derived from bacteria that infect the plants.

The extra EPSP synthase allows the plant to withstand the effects of glyphosate. Biotechnology labs attempted to utilize plant genes to boost EPSP synthase activity. This was partially to take advantage of a loophole in US law that permits regulatory approval for transgenes in organisms that have not been derived from bacteria pests.

Few studies have examined whether transgenes which confer glyphosate resistance can make plants more competitive for reproduction and even survival after they are introduced to wild or weedy relatives by cross-pollination. "The common belief is that any transgene will confer disadvantage in the wild, in the absence of pressure to select, because the extra machinery would reduce the fitness," says Norman Ellstrand who is a plant geneticist at the University of California in Riverside.

Lu Baorong (an ecologist at Fudan University, Shanghai) has now challenged that view. ラウンドアップ al It shows that glyphosate resistance can give a significant fitness boost to the weedy rice crop called Oryza sativa even when it is not being used.

In the study published this month in New Phytologist 1, Lu and his coworkers genetically altered the rice cultivar to overexpress the species' own EPSP synthase. They crossed the modified rice with a weedy cousin.

The group then let the offspring of crossbreeding to cross-breed with one other to create second-generation hybrids. They were identical genetically apart from the number of EPSP synthase genes they had. The ones with more copies expressed higher amounts of the enzyme and also produced more of the amino acid tryptophan than the unmodified ones.

Researchers also discovered that plants with transgenic genes were more photosynthesis-intensive as well as produced more flowers and produced 48 to 125 percent fewer seeds per plant than nontransgenic hybrids. ラウンドアップ This was in spite of the fact that glyphosate wasn't present.

Lu believes that making weedy, invasive rice more competitive may make it more difficult for farmers to repair the damage caused by this bug.

Brian Ford-Lloyd of Brian Ford-Lloyd from the University of Birmingham, UK Brian Ford-Lloyd, a researcher at the University of Birmingham in the "If the EPSP synthase gene is introduced to wild rice species, their genetic variety, which was really important in conserving it, could be at risk because it could surpass the regular varieties." "This is a prime instance of the most probable and damaging negative effects of GM crops on the environment."

ラウンドアップ The public belief that genetically-modified crops that contain additional copies of their genes are more secure is questioned by this study. Lu declares that "our study does not prove that this is the case."

Researchers believe that these findings should prompt an overhaul of how genetically modified plants will be controlled in the future. Ellstrand claims that some people believe biosafety regulations can be relaxed since we have over two years of genetic engineering. "But the study still suggests that new products need careful evaluation."


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