Disease-resistant tomatoes fight lethal pests

In the battle against thrips, Cornell breeder Martha Mutschler-Chu has developed a new weapon: a tomato that packs a powerful one-two punch to deter the pests and counter the killer viruses they transmit.

Thrips are tiny insects that pierce and suck fluids from hundreds of species of plants, including tomatoes, grapes, strawberries and soybeans. They also transmit such diseases as the tomato spotted wilt virus, causing millions of dollars in damage to U.S. agricultural crops each year.

Adapting a novel form of insect resistance discovered in a wild plant native to Peru, Mutschler-Chu, professor of plant breeding and genetics, first isolated the resistance. She found that it was mediated by droplets of sugar esters, called acylsugars, that are produced and exuded from hairs (trichomes) that cover the plants. The acylsugars don't kill the insects, but deter them from feeding or laying eggs on the plants. The process does not require genetic modification and is completely safe.

After successfully transferring the resistance into new lines and breeding out undesirable traits, her team added a second layer of protection: one or both of two natural genes known to resist the so-called TOSPO viruses, which include tomato spotted wilt virus.

The "dual resistant" insect and virus varieties may reduce or even eliminate the need for pesticides in several regions.