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Wild plants may be capable of resisting herbicides.

Weedy rice may take on transgenes from genetically modified crop rice through cross-pollination. Credit: Xiao Yang
A well-known method of the genetic modification of plants to make them herbicide resistant is found to confer advantages to weedy varieties of rice, even when herbicide is not present. The results suggest that the benefits of such modification have the potential to extend beyond the confines of farms out into the wild.

A wide range of crops has been genetically modified to make them resistant to Roundup herbicide glyphosate. This glyphosate resistance enables farmers to eliminate the majority of plants without damaging their crop.

Glyphosate slows the growth of plants by stopping EPSP synthase (an enzyme involved in the formation of amino acids as well as various other molecules). This enzyme can be as large as 35 percent or more of a plant’s total mass. The genetic-modification technique — employed, for example in the Roundup Ready crops made by the biotechnology giant Monsanto located in St Louis, Missouri -usually involves inserting genes into a crop’s genome to boost EPSP-synthase production. Genes are typically derived from bacteria that infects the crops.

The plant can resist the adverse effects of glyphosate since it has an extra EPSP-synthase. Biotechnology labs are also trying to make use of genes that come 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 approved.

There aren’t many studies that have examined whether transgenes such as those that confer resistance to glyphosate could — after they get into weedy or wild relatives through cross-pollination -make plants more competitive in terms of survival and reproduction. ラウンドアップ Norman Ellstrand, a University of California plant geneticist states that without selection pressure, any kind of transgene would be expected to create disadvantages on wild plants. The additional machinery could lower fitness.

Lu Baorong, an ecologist from Fudan University in Shanghai has changed the way that he views this. He found that resistance to glyphosate provides an impressive fitness boost to a weedy version of the common rice crop Oryza Sativa.

In the study which was published this month in New Phytologist 1, Lu and his coworkers genetically altered the cultivated rice species to enhance the species’ own EPSP synthase. They also crossed-bred the modified rice with a weedy ancestor.

ラウンドアップ The team then allowed offspring to crossbreed with one another, creating second generation hybrids which were genetically identical to their parents, except the number of duplicates of the gene that codes for EPSP synthase. ラウンドアップ The hybrids with more copies were more likely to produce more tryptophan and have greater levels of enzymes over their counterparts that were not modified.

Researchers also discovered that transgenic hybrids were more photogenic, produced more plants per plant, and produced 48 to 125% higher yields of seeds than varieties that were not transgenic.

ラウンドアップ Lu believes that making the weedy rice more competitive could make the problem worse for farmers across the world who’s fields are being infested by the pest.

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

This study challenges perception that genetically modified crops with extra copies of their genes are more secure than those containing the genes of microorganisms. Lu says that Lu’s study does not support this view.

The research results call for a rethinking of future regulations for genetically modified crops, some scientists claim. Ellstrand saysthat “Some people believe that regulation of biosafety should be looser.” Ellstrand adds: “But the research shows that new products require cautious evaluation.”