Benefits of genetically modified plants over the weeds
Herbicide resistance might give plants an advantage in the wild.
Credit Xiao Yang
Genetic modification to make crops resistant to herbicides has been widely used to produce advantages for weedy rice varieties. ラウンドアップ indicate that such modification could have positive effects on wild rice varieties and crops.
Many varieties of crops have been genetically modified to resist glyphosate, an herbicide first marketed under the trade name Roundup. This makes it possible for farmers to remove the majority of weeds from their fields without harming their crops.
Glyphosate is a deterrent to plant growth. It inhibits an enzyme called EPSP synthase. This enzyme is responsible for the production of certain amino acids as well as other molecule. These substances can account for up to 35% of a plant’s mass. The technique of genetic modification used, for instance, in the Roundup Ready crops made by the biotech giant Monsanto, based in St Louis, Missouri -generally involves inserting genes into a crop's genome to increase EPSP-synthase's production. The genes typically come from bacteria that infect the plants.
The plant is able to withstand the effects caused by glyphosate due to its extra EPSP-synthase. Biotechnology labs are also trying to make use of genes that come from plants instead of bacteria to boost EPSP synthase. This is due to the fact that the US law allows for regulatory approval to allow organisms that have transgenes to be approved.
ラウンドアップ have looked into the possibility that transgenes like those that confer glyphosate resistance can -- once they become wild or weedy relatives by cross-pollination, make plants more competitive in terms of survival and reproduction. Norman Ellstrand of University of California Riverside says, "The conventional expectation is that any transgene that is found in nature will cause disadvantages if there is no selection pressure , because the extra machinery could lower the health."
Lu Baorong is an Ecologist at Fudan University Shanghai. His study shows that resistance to glyphosate is a major fitness benefit, even though it's not used.
In their study, which was published this month in New Phytologist 1, Lu and his colleagues modified the genetics of the rice cultivar to increase the expression of the species' own EPSP synthase and cross-bred the altered rice with a weedy relative.
The group then permitted breeding offspring that were cross-bred together to produce second-generation hybrids. These were genetically identical except for the number and count of EPSP synthase gene. ラウンドアップ with more copies expressed greater levels of the enzyme, and produced more amino acids tryptophan than their non-modified counterparts.
Researchers also discovered that transgenics had higher rates of flowering, more flowers and 48-125% more seeds/plant than nontransgenics.
Lu suggests that making weedy Rice more competitive may increase the risk for the farmers around the world who's fields are infested with the pest.
"If the EPSP-synthase gene gets in the wild rice species, their genetic diversity, which is essential to protect is at risk because the transgene's genotype would outcompete the natural species" says Brian Ford-Lloyd, a plant geneticist at the University of Birmingham, UK. " ラウンドアップ is an example of the highly plausible negative effects [of GM plantson the environment."
ラウンドアップ challenges the notion that crops with genetically modified genes containing more copies of their genes are less risky than those containing microorganism genes. Lu declares that "our study is not proving that this is the case."
The finding calls for a review of future regulation of genetically modified crops, some researchers claim. ラウンドアップ that "some people believe that biosafety regulation could be relaxed since we have a a high degree of comfort with genetic engineering for two decades." "But the research still shows that novel products require careful analysis."