How CRISPR Could Help Save Crops from Devastation Caused by Pests

Abstract

Central California grape-grower Steve McIntyre was familiar with Pierce's Disease. But that did not prepare him for what he saw when he visited his brother's Southern California citrus and avocado farm in 1998. The disease, which causes vines to wither and grapes to deflate like old balloons, had long existed in California. But the infection he saw on a farm adjacent to his brother's property seemed different. Blocks of grapes looked as though their irrigation had been entirely cut. Less than a decade after it was first identified in California, an invasive insect the glassy-winged sharpshooter (Homalodisca vitripennis) had turned the bacterium that causes Pierce's from a nuisance to a nightmare. The oblong bug, with wings like red-tinged stained glass, is quicker and flies further afield than sharpshooters native to the state, and it can feed on tougher grapevines. Its arrival, which the state suspects was in the late 1980s, supercharged the spread of the disease. Through inspections and targeted pesticide spraying, the state has largely been able to confine the invasive sharpshooter to Southern California. But the disease still has no cure, and it is at risk of getting worse and harder to combat due to climate change. Researchers are now looking to add cutting-edge technology to California's anti-Pierce's arsenal, by changing the genome of the glassy-winged sharpshooter so that it can no longer spread the bacterium. Such a solution is possible thanks to CRISPR gene-editing technology, which has made modifying the genes of any organism increasingly simple.