1 Cell Biology and Neurobiology, Department of Biology, Faculty of Science, Københavns Universitet2 Purdue University3 Kansas State University4 Baylor College of Medicine5 University of Geneva Medical School6 University of Rochester7 Lund University8 University of Chicago9 unknown10 University of Rochester11 University of Chicago12 Cell Biology and Neurobiology, Department of Biology, Faculty of Science, Københavns Universitet
Gall-forming arthropods are highly specialized herbivores that, in combination with their hosts, produce extended phenotypes with unique morphologies . Many are economically important, and others have improved our understanding of ecology and adaptive radiation . However, the mechanisms that these arthropods use to induce plant galls are poorly understood. We sequenced the genome of the Hessian fly (Mayetiola destructor; Diptera: Cecidomyiidae), a plant parasitic gall midge and a pest of wheat (Triticum spp.), with the aim of identifying genic modifications that contribute to its plant-parasitic lifestyle. Among several adaptive modifications, we discovered an expansive reservoir of potential effector proteins. Nearly 5% of the 20,163 predicted gene models matched putative effector gene transcripts present in the M. destructor larval salivary gland. Another 466 putative effectors were discovered among the genes that have no sequence similarities in other organisms. The largest known arthropod gene family (family SSGP-71) was also discovered within the effector reservoir. SSGP-71 proteins lack sequence homologies to other proteins, but their structures resemble both ubiquitin E3 ligases in plants and E3-ligase-mimicking effectors in plant pathogenic bacteria. SSGP-71 proteins and wheat Skp proteins interact in vivo. Mutations in different SSGP-71 genes avoid the effector-triggered immunity that is directed by the wheat resistance genes H6 and H9. Results point to effectors as the agents responsible for arthropod-induced plant gall formation.
Current Biology : Cb, 2015, Vol 25, Issue 5, p. 613-620