Protecting crops by blocking insect genes: the case for RNA interference

From the potato farms of Prince Edward Island to the cornfields of Iowa, there is a never-ending struggle between farmers and insects. Farmers apply chemical pesticides to protect their crops, which drive the evolution of more insecticide-resistant pests. This, in turn, forces farmers to use insecticides more frequently and at higher doses, which then selects for even more resistant insects. And so on and so on.

In an effort to gain the upper hand, researchers are turning to transgenic plants as a way to increase crop yield while reducing pesticide use. For example, some species of corn, cotton, and potato plants have been engineered to produce a bacterial toxin called Bt that is lethal to insects. Insects that eat leaves from Bt-producing plants ingest the toxin and are killed. But Bt isn’t effective against all agricultural pests and resistance has already been documented in some insects.

Left uncontrolled, potato beetles can completely destroy crops.
Left uncontrolled, potato beetles can completely destroy crops.

A promising area of transgenic plant research is focused on the use of RNA interference, or RNAi, to control insect pests. For any gene to be expressed, the DNA must first be read and converted into RNA. The RNA message is then decoded to produce a protein. Think of your cell as a house and the DNA as the master building plan for that house. Every time you need to make a repair, the general contractor consults the building plan and sends a message to the tradesperson to make the component that is needed. The RNA is the message that your cell uses to produce the parts needed to keep everything running smoothly. In RNAi, the RNA message is intercepted and the proper parts are not made. When the RNA message is for an essential cellular component, blocking the message can lead to cell death and if enough cells are affected, the death of the entire organism. Continue reading