Support Provided ByLearn More

RNA Spray Could Make GMOs Obsolete

Through RNA interference, or the process of temporarily barring gene expression, Monsanto scientists have been able to stop a pest from eating crops by spraying RNA that shuts down a gene the insects need to survive directly onto the plants.

ByAbbey InterranteNOVA NextNOVA Next
One challenge is confirming that every crop in the field is sprayed.

As Scotland moves forward to ban genetically modified crops , Monsanto is developing a way to alter crops without touching their genes.

Through RNA interference, or the process of temporarily barring gene expression, Monsanto scientists have been able to stop the Colorado potato beetle from eating crops. Instead of modifying the crop’s genes, they’ve sprayed RNA that shuts down a gene the insects need to survive directly onto the crops. When the beetles eat the plant, the ingested RNA will eventually cause them to die through inhibiting the necessary gene.

Antonio Regalado, reporting at MIT Technology Review, explains RNA interference further:

The mechanism is a natural one: it appears to have evolved as a defense system against viruses. It is triggered when a cell encounters double-stranded RNA, or two strands zipped together—the kind viruses create as they try to copy their genetic material. To defend itself, the cell chops the double-stranded RNA molecule into bits and uses the pieces to seek out and destroy any matching RNA messages. What scientists learned was that if they designed a double-stranded RNA corresponding to an animal or plant cell’s own genes, they could get the cells to silence those genes, not only those of a virus.

Other companies, all of which are hoping to avoid the controversy they face when they genetically modify crops directly, are exploring the genetic spray alternative to GMOs. These sprays can be created and applied quickly, providing protection if the plants are infested by a never-before-seen virus or insect. They could even be used to endow plants with advantageous, temporary traits. For example, farmers could spray RNAis that bestow corn plants with drought-resistance, saving a harvest during hot, dry weather.

Support Provided ByLearn More

Such sprays can only turn off genes for a few days or weeks at a time, so all efforts would be temporary. If a new set of insect invaders enters the field of crops weeks after the last RNA spray, the plants would no longer be protected. But the approach has it’s benefits, too, because the plants’ genes that were affected to help them survive in a water shortage would revert back to their original states when the water shortage ends. This means they could thrive in both conditions. In addition to that, if insects evolve to survive the RNA spray, the scientists could switch which gene they’re affecting. Monsanto is hoping to improve the sprays to last for months—some scientists have already been successful in creating these long-lasting sprays.

Since the spray target specifics genes that only that certain targeted insects have, it wouldn’t affect beneficial bugs that currently suffer from pesticide use, such as bees. This differentiates the spray from traditional insecticides, which are indiscriminate killers.

Despite the lack of evidence of harmful effects of the spray, it will most likely face stiff opposition. Some worry the spray will be hard to control, and wind could blow it to surrounding areas. Others argue that the RNA interference might silence important genes in humans when we eat the crops, but no trustworthy studies so far have shown that to be true.

Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens.

Photo Credit: Public Domain

Funding for NOVA Next is provided by the Eleanor and Howard Morgan Family Foundation.

Major funding for NOVA is provided by the David H. Koch Fund for Science, the Corporation for Public Broadcasting, and PBS viewers. Additional funding is provided by the NOVA Science Trust.