Spit, Decoys, and Aspirin: Weapons in the Plant-Aphid War

Saturday, October 5, 2013: 4:25 PM
212 B (Henry B. Gonzalez Convention Center)
Gustavo MacIntosh, PhD , Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA
Plants and insect herbivores are engaged in an evolutionary "arms race". This arms race is particularly evident in the interaction between plants and aphids,

specialized insects that feed directly from the phloem sap and are some of the most

devastating pests of crops. Research in my laboratory aims to find out the

mechanisms of basal plant defense, how aphids avoid these basal defenses to

establish successful colonies on susceptible plants, and the alternative defense

strategies deployed by plant varieties resistant to aphid colonization.

We analyzed the changes in plant gene expression and in the accumulation of

different plant metabolites after aphid attacks to start the dissection of

compatible or incompatible interactions, using different plant models (soybean and

Arabidopsis). We found that plants use an arsenal of chemical weapons as basal

defense mechanisms against aphids; however, aphids can suppress the signals that

trigger these defenses in susceptible plants through a decoy that instead trick

plants to respond to a non-existent water stress. This decoy is likely elicited by

small proteins present in the aphid's saliva, and it blocks not only the defense

against aphids but also makes plants more susceptible to attacks by other pests. On

the other hand, plants that are resistant to aphid colonization seem immune to the

aphid decoy and are able to establish a rapid defense that blocks aphid growth.

Understanding these interactions will be useful for better crop management

strategies and the development of novel plant varieties with increased resistance to

these pests.