Notes

Genetically modified crops pass advantages to the weeds

In the wild, plants can be treated with herbicides.

Credit goes to Xiao Yang
A genetic-modification technique used widely to create crops that are resistant to herbicides has been found to provide advantages to a weedy form of rice even in absence of the herbicide. The finding suggests that the benefits of such modification could extend beyond farms and into the wild.

A variety of crops have been genetically altered so that they can ward off glyphosate. The herbicide was initially sold under the tradename Roundup. The resistance to glyphosate permits farmers to get rid of weeds without causing any damage to their crop.

Glyphosate may hinder the growth of plants by inhibiting EPSP synase which is an enzyme that plays a role in the creation of amino acids and other chemicals which comprise around 35% of plants' mass. Genetic modification -- utilized, for instance, in the Roundup Ready crops made by the biotechnology giant Monsanto, based in St Louis, Missouri -usually includes inserting genes into the crop's genome to increase EPSP-synthase's production. Genes typically come from bacteria that cause disease to plants.

The extra EPSP synthase allows the plant to withstand the effects of glyphosate. Biotechnology labs have also tried to utilize plants' genes instead of bacteria to increase EPSP-synthase levels, in part to exploit a loophole that is in US law that facilitates the approval of regulatory agencies for organisms that carry transgenes that are not that are derived from bacteria.

Few studies have tested whether transgenes such as those that confer glyphosate resistance could -- after they are weedy or wild relatives through cross-pollination, make plants more competitive in terms of survival and reproduction. Norman Ellstrand is a University of California Riverside plant geneticist. "The expectation is that any transgene could cause disadvantages in the wild, in the absence of select pressure, because it would reduce the fitness of the plant," Ellstrand said.

However, a new study conducted by Lu Baorong, an ecologist at Fudan University in Shanghai, challenges that view It reveals that a weedy variant of the standard rice plant, Oryza sativa is given an important boost in fitness due to the resistance to glyphosate even when glyphosate isn't applied.

In the 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. They also crossed-bred the modified rice with a weedy relative.

The group then permitted cross-breeding offspring to be bred with each other to produce second-generation hybrids. These were genetically identical except for the number and count of the EPSP synthase gene. As expected, the ones with more copies had more enzyme activity and an increased amount of amino acid tryptophan in comparison to the unmodified counterparts.

Researchers also discovered that transgenic hybrids grew between 48 to 125 percent more seeds per plant, and had higher photosynthesis rates and produced more shoots than non-transgenic ones.

Making weedy rice more competitive may cause more problems for farmers all over the world where plots are ravaged by the pest, Lu says.

"If the EPSP-synthase gene gets in the wild rice species, their genetic diversity, which is essential to protect, could be threatened because the transgene's genotype could outcompete normal species," says Brian Ford-Lloyd an expert in plant genetics at the University of Birmingham, UK. " https://www.asian-tapas.com/auto-draft-81/ is among the most evident instances of the highly probable negative consequences [of GM crops] on the natural environment."

The public has a perception that genetically engineered crops that have additional copies of microorganisms' genes are safer than ones with only the genes of their owners. Lu says that the study "shows that this is not always true".

Researchers have said that this finding calls for rethinking the future regulation on genetically modified crops. "Some individuals are suggesting that biosafety regulations can be relaxed because we have an extremely high level of satisfaction in the last two years of genetic engineering" says Ellstrand. "But the research indicates that innovative products require careful evaluation."


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