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Wild plants might be able to resist herbicides.

Weedy rice can take on transgenes from genetically modified rice by cross-pollinating. Credit: Xiao Yang
It has been established that a genetic-modification technique that is used extensively to make crops herbicide-resistant, gives advantages to a weedy variety of rice. This suggests that such genetic modification may also have potential to impact wild animals.

A range of crops have been genetically modified so that they become resistant to Roundup herbicide glyphosate. This resistance allows farmers to remove the majority of herbicides from their fields, without causing harm to their crops.

Glyphosate acts as an inhibitor of plant growth. It blocks an enzyme known as EPSP synthase. This enzyme is involved in the creation of specific amino acids as well as other molecule. These compounds can make up as much as 35% of a plant’s mass. The genetic-modification technique is used in, for instance, Roundup Ready plants made by Monsanto Biotechnology Inc., a biotech firm that is headquartered in St Louis, Missouri. It involves inserting genes into the genome of the crop to increase EPSP synthase synthase synthase production. Genes are usually derived from bacteria that infects crops.

The plant can withstand the effects of glyphosate because of the additional EPSP synthase. Biotechnology labs are also trying to utilize genes from plants instead of bacteria to boost EPSP synthase. ラウンドアップ This is due to the fact that the US law allows for regulatory approval that allows organisms with transgenes to be accepted.

Few studies have investigated the possibility that transgenes like glyphosate-resistant genes can — once introduced to weedy or wild plants by cross-pollination — enhance the competition of plants in reproduction, survival 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 additional machinery could lower fitness.

Lu Baorong (an ecologist at Fudan University, Shanghai) has now challenged that view. It has shown that resistance to glyphosate can provide an impressive fitness boost to a weedy rice crop known as Oryza sativa even when it is not being 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 enhance its own EPSP synthase and cross-bred the modified rice with a weedy cousin.

ラウンドアップ The researchers then allowed the offspring of cross-breeding to be bred together to produce second-generation hybrids. They were genetically identical with the exception of the number and count of the EPSP synthase gene. The ones who had more copies expressed higher levels of the enzyme, and produced more amino acid tryptophan than their unmodified counterparts.

Researchers also discovered that transgenic hybrids have higher rates of photosynthesis, produced more flowers and shoots and produced 48-125% more seeds per plant than non-transgenic hybrids -with or without glyphosate.

Lu suggests that making weedy Rice more competitive may increase the risk for the farmers around the globe whose fields are being infested by the pest.

Brian Ford-Lloyd is a UK plant geneticist. He says, “If the EPSP synthase gene gets in the wild rice species their genetic diversity will be threatened which is really significant because the genotype with transgene outcompetes the normal species.” ラウンドアップ “This is among the most clear instances of the extremely damaging effects of GM crops] on the environment.”

ラウンドアップ This study also challenges the notion that genetically modified crops containing additional copies of their genes are safer than those that contain microorganisms’ genes. Lu says that the study “shows that this isn’t always true”.

According to some researchers, the finding suggests that the future regulation of genetically engineered plants should be rethought. Ellstrand believes that some believe biosafety regulations can be relaxed because we’ve had over two years of genetic engineering. “But the study shows that novel products still need an unbiased examination.”