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Wild plants may be capable of resisting herbicides.

ラウンドアップ Credit: Xiao Yang
A common technique for the genetic modification of plants to make them resistant to herbicides has been found to give advantages to weedy varieties rice even when the herbicide isn’t in use. The results suggest that this modification could positively impact wild rice varieties and crops.

Many cultivars are genetically modified so that they can ward off the glyphosate. This herbicide was first sold under the tradename Roundup. Farmers can eliminate most the weeds that grow in their fields with glyphosate and not harm their crops by having this resistance.

Glyphosate can inhibit plant growth by blocking EPSP synase which is an enzyme that plays a role in the creation of amino acids and other chemicals that comprise about 35% of plants’ mass. ラウンドアップ The technique of genetic modification employed by Monsanto’s Roundup Ready crops, which are based in St Louis (Missouri), generally involves inserting genes into the DNA of a plant to boost EPSP synthase’s production. Genes are usually derived from bacteria that have been infected by plants.

The plant is able to withstand the effects glyphosate thanks to the extra EPSP synthase. ラウンドアップ Biotechnology labs have also tried to use genes from plants rather than bacteria to boost EPSP-synthase production partly to make use of the loophole within US law that permits the approval of regulatory agencies for organisms that carry transgenes that aren’t that are derived from bacteria.

A few studies have looked into whether transgenes such glyphosate-resistant genes are able to — when introduced to wild or weedy plants through cross-pollination increase the competitiveness of these plants in survival, reproduction and growth. Norman Ellstrand, a University of California plant geneticist says that without competition, any kind of transgene could be expected to confer disadvantage on wild plants. The added machinery will lower fitness.

A new study, led by Lu Baorong, an ecologist from Fudan University in Shanghai, is challenging that notion and shows that the weedy form of the common rice plant, Oryza sativa is given an impressive fitness boost due to resistance to glyphosate, even when glyphosate is not applied.

Lu and coworkers modified the cultivars of rice to improve its EPSP synthase. The modified rice was then cross-bred with a wild-type relative.

The team allowed the offspring of crossbreeding to crossbreed with each other, creating second-generation hybrids that are genetically identical with each other , with the exception of the number of copies of the gene that encodes EPSP synase. The ones with more copies expressed higher levels of the enzyme and also produced more of the amino acid tryptophan than their non-modified counterparts.

https://www.amazon.co.jp/日産化学-除草剤-原液タイプ-ラウンドアップマックスロード-500ml/dp/B001GH6XVQ Researchers also discovered that transgenics have higher rates, had more flowers and 48-125% more seeds/plant than nontransgenics.

Making the weedy rice more competitive can increase the issues it creates for farmers around the world who’s plots are infested by pests, Lu says.

“If the EPSP-synthase genes are introduced in the wild rice plant, their genetic diversity, which is essential to protect, could be threatened because the transgene’s genotype will outcompete the normal species,” Brian Ford-Lloyd who is a plant geneticist at the University of Birmingham, UK. “This is one example of the most plausible and damaging impacts of GM crops on the environment.”

ラウンドアップ The public believes that plants with genetically modified genes containing more replicas of their own genes than microorganisms are safe. This is however questioned by the study. Lu states that “our study is not proving that this is the case.”

Researchers believe that their findings require a rethinking of the way that genetically modified crops are regulated in the future. Ellstrand thinks that biosafety rules could be relaxed as we have a great level of comfort from two decades worth of genetic engineering. “But the study demonstrates that novel products still need careful evaluation.”

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