Galls are atypical plant growths induced by insects, mites, fungi, nematodes, bacteria, or viruses that provide the attacking organism with enhanced nutrition and protection from environmental vicissitudes, predators, and parasites (Mani, 1964). Around 300 B.C., the Greek philosopher and founder of botany Theophrastus, described ten kinds of insect galls found on oak trees and discussed their economic uses (Senn, 1942). Probably at least since this time, students of natural history have wondered how insect galls are formed. Are they a plant “wound response” or an “extended phenotype” of the attacking organism (Dawkins, 1982)? We have discovered that aphids produce hundreds of homologous novel effector proteins that they inject directly into plant cells to induce galls. These proteins contribute to almost total rewiring of the plant transcriptome, dramatically altering cellular physiology and development. These aphid genes have evolved rapidly, as expected for genes that manipulate host defenses, and the genes encoding these proteins have many unusual properties that may have facilitated their rapid divergence.
This seminar will take place in the Schlich Lecture Theatre in the Department of Plant Sciences.