Scientists Uncover Plants' Defense Mechanism Against Pests

Scientists from the Boyce Thompson Institute in New York, the US Department of Agriculture, the University of Neuchatel's Institute of Biology in Switzerland, and the Max Planck Institute for Chemical Ecology in Germany have tracked an underlying biochemical pathway for maize defense against the corn leaf aphid Rhopalosiphum maidis, a harmful sap-sucking insect.

To investigate natural variation in aphid resistance, researchers fed 25 genetically diverse lines of maize to aphids and measured aphid reproduction on each line. They also analyzed levels of specific defense chemicals produced by maize. Using quantitative genetic approaches, the researchers located a group of defense genes that regulate the metabolites and discovered a process that actually increases maize sensitivity to aphids. The researchers found a previously unidentified (methyltransferase) enzyme that converts one benzoxazinoid into another and causes higher aphid-sensitivity. Maize varieties with a natural knockout mutation in the defense gene linked to this enzyme expressed lower amounts of the methylated benzoxazinoid and surprisingly, higher aphid resistance.

See BTI's news release at http://bti.cornell.edu/new-study-uncovers-plant-defense-mechanisms-against-pests/.