Gene drives – bits of DNA that trick evolution and can spread even if they are harmful – have been successfully tested in plants for the first time. This approach can be used to clear out invasive plants and superweeds without harming other species, potentially reducing herbicide use. It could also help save species by spreading genes that make them more resistant to disease and better able to cope with global warming.

Genes work by distorting the probability that an organism will inherit a piece of DNA. Most plants and animals have two copies of each gene. This usually means that there is a 50% chance that a particular copy will be passed on to offspring. With a gene drive, the chance increases to, say, 80 percent, allowing genes to spread even if they are harmful.

There are many natural gene drives that function through different mechanisms. In 2013, the first artificial gene drive was created using CRISPR gene editing technology.

It copies itself from one chromosome to another. That is, all descendants inherit it. This approach is called a homing gene drive because the drive itself is copied to a specific site.

bruce hay The researchers at the California Institute of Technology used a different approach called cleave-and-rescue. The gene drive consists of CRISPR elements that target and destroy copies of both key genes needed for pollen and egg formation. However, the drive also contains a version of this gene that functions without being destroyed.

This means that pollen and eggs that do not inherit the gene drive will lack important genes and will not develop. Only pollen and eggs with the gene drive will develop normally, so all offspring will inherit it.

Hay says the cleave-and-rescue approach is more robust than homing drives because it's much easier to destroy genes than to copy and paste them. He says it works on all animals, not just plants, and could be used to rid islands of rats and mice that are wiping out native species.

Hay's team tested a working version of this drive – one designed only to spread, not kill – on Thale cress. Arabidopsis.Another team led by Yang Liu Chinese Academy of Sciences Even in Beijing I have submitted a paper describing a similar gene drive But that approach isn't as powerful, Hay says.

He and his team are currently planning driving tests in Pigweed (amaranth palmeri), a herbicide-resistant superweed and a major problem for farmers in many parts of the world. “This is the poster child for developing broad-based resistance to all existing herbicides,” Hay says.

Additionally, this technology could be adapted to control weeds without spreading indefinitely. For example, pollen could be used to create male plants that kill all female offspring. Planting these male plants annually around the farm will prevent seed production and eradicate the weed species from the field after a few years.

“If you just exclude women, you end up collapsing the entire local population, but not the global population,” Hay says. However, this female-killing trait will disappear if no male plants with it are planted.

Hay said this approach is much more likely to be approved by regulators than gene drives, which continue to spread until resistance emerges. In fact, a similar approach is already being used in several countries by a company called Oxitec to control malaria-carrying mosquitoes.

but, paul nave Researchers at the University of Copenhagen in Denmark doubt whether regulators will approve the use of gene drives to control weeds. “I think the chances of getting approval to release gene drives for agricultural use are low at this point. Healthcare and biodiversity conservation may be an easier sell,” he says.

Another big problem, Neve says, is that plants typically produce only one generation per year, and it takes 10 to 30 generations for drives to become widespread. “How can we spread gene drives fast enough to achieve meaningful weed control in a realistic time frame?”