A Roundup-ready superweed which grows superfast, even if Roundup isn’t there

The world’s best-selling weedkiller is Roundup (glyphosate). Some of the most popular genetically modified (GM, genetically engineered, GE) crops are Roundup Ready. That means they don’t die when sprayed with glyphosate, while weeds die.

Now Science 2.0 tells us about a Roundup-ready superweed which grows superfast, even if Roundup isn’t there.

Here’s some science about how Roundup Ready crops work. They involve a plant enzyme called 5-enolpyruvylshikimate 3-phosphate synthase (EPSP synthase). That enzyme is normal in plants. It lets them grow. If you like its long name, you’re more of a biochemist than I am. But the gene for EPSP synthase, epsps, is worth remembering because it comes up in some new science about rice.

Roundup Ready rice (Oryza sativa) for people to eat isn’t yet grown commercially. But that time may come because rice is a staple food for many millions of people. Farmers who grow rice don’t like the weedy rice (O. sativa f. spontanea) that often appears on their land.

I’m concerned about biosafety. Superweeds can evolve when transgenes escape from GM crops to weeds. Roundup ready weeds? Oh dear. Farmers would dislike weedy rice even more if it became Roundup Ready.

Why not use less Roundup? At least use it less often and on fewer fields? That would reduce the selection pressure towards Roundup resistance. But now we hear of Roundup resistance continuing to give an advantage, even without the obvious selection pressure of the Roundup.

Science 2.0 tells us about a Roundup-ready superweed which grows superfast, even if Roundup isn’t there. Allison Snow and her team adjusted the ‘expression’ of the epsps gene. That’s to say, using more GM, they made rice plants which produced more EPSP synthase than the parent plants had produced. The idea was that these new plants would be Roundup Ready in a new way. They’d make so much EPSP synthase that they’d be able to survive Roundup.

The extra EPSP synthase made the new rice plants grow extra fast. Not surprising, since all plants require EPSP synthase to grow. But worrying because this could happen in weedy rice.

Prof Snow says, ‘Our next question is whether this method of enhancing plant growth could be developed for any crop. We want to know whether growers could get higher yields in the crop and then, if it happened to cross with a related weed, whether it might make the weed more prolific as well.’

This is an experimental study, not something that’s happened on farms. Yet. Here’s the science. We don’t know whether the biotech companies are doing this too. Their research is done in private, to protect their commercial interests.

I haven’t seen any comments from Prof Snow about whether the new kind of Roundup Ready superweed could establish itself in rice fields. It can survive Roundup, yes. But can it survive the other pressures of plant life?

At this stage we don’t know what may happen with this superweed. We just know that it grows fast, whether or not there’s any Roundup.


About argylesock

I wrote a PhD about veterinary parasitology so that's the starting point for this blog. But I'm now branching out into other areas of biology and into popular science writing. I'll write here about science that happens in landscapes, particularly farmland, and about science involving interspecific interactions. Datasets and statistics get my attention. Exactly where this blog will lead? That's a journey that I'm on and I hope you'll come with me.
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