Plants engineered to silence pests

Nobel prize-winning medical research has found an agricultural niche, as two teams of researchers have engineered crop plants to combat the troublesome pests that feed on them by switching off their genes.

In 2006, Craig Mello and Andrew Fire won the Nobel Prize for Physiology and Medicine for their discovery of RNA interference, a process whereby specific, unwanted genes can be switched off. RNA is a template for genes. By inserting into the cell a short piece of RNA, called an interfering RNA, which is the mirror image of the section of RNA that codes for a particular gene, that section can be cancelled out or silenced. This prevents that specific gene from being made.

Now, researchers at Monsanto Company in Missouri, US, have turned plants against their pests using the same technology. Targeting the western corn rootworm - an insect that causes an estimated $1 billion worth of damage to corn crops every year - they inserted a short section of RNA that silenced a gene that the rootworm needs in order to grow.

A second team, based at the Shanghai Institute of Biological Sciences, China, used the same technology to target the cotton bollworm, a moth larva that causes huge damage to cotton plants. They silenced the gene that allows the bollworm to tolerate high levels of gossypol - a toxic polyphenol in cotton. Both insects have developed resistance to insecticides - this new approach allows the plants to hijack the pests' own cell biology and turn it against them.