Modified maize that kills with RNA is given go-ahead in the US

FOR the first time, a crop that produces an RNAi-based pesticide has got the green light.

The US Environmental Protection Agency has approved a genetically modified corn known as SmartStax Pro. In addition to producing two Bt toxins to kill any western corn rootworm larvae that try to eat it, the plant produces a piece of RNA that shuts down a specific gene inside the larvae, killing them.

On paper at least, such RNA interference (RNAi) is the perfect pesticide: it kills the target species while leaving others untouched. But it only works in some insects. In large animals like humans, RNAs, and proteins like the Bt toxins, get destroyed in the gut. We already eat gene-silencing RNAs, because many organisms produce them in their cells.

It could still be a few years before farmers in the US start growing the maize, made by agrochemical firms Monsanto and Dow. “We’re still awaiting import approval from several countries, which is why we’re looking at an end-of-decade commercial launch,” says Jeffrey Neu of Monsanto. The company is also developing RNAi-based sprays to protect crops against pests and even to alter crop traits.

This article appeared in print under the headline “RNAi crop approved”