|ZHAO, CHAOYANG - The Ohio State University|
|NAVARRO ESCALANTE, LUCIO - Purdue University|
|RICHARDS, STEPHEN - Baylor College Of Medicine|
|STUART, JEFFREY - Purdue University|
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2015
Publication Date: 10/9/2015
Citation: Zhao, C., Shukle, R.H., Navarro Escalante, L., Chen, M., Richards, S., Stuart, J.J. 2015. Avirulence gene mapping in the Hessian fly (Mayetiola destructor) reveals a protein phosphatase 2C effector gene family. Journal of Insect Physiology. 84:22-31. doi:10.1016/j.jinsphys.2015.10.001.
Interpretive Summary: The Hessian fly is a major pest of wheat in the United States, and the best method to prevent damage from the pest is through resistant wheat. However, the use of resistant wheat results in populations of the fly that can overcome resistance in wheat. Understanding how the insect damages wheat and how it is able to overcome resistance is critical to ensuring the continued protection of wheat. The damage to wheat from the pest is due to larval feeding. This damage is caused by proteins secreted by the larvae into the wheat plant. These proteins that damage the wheat plant are called ‘effector proteins’ because they effect damage to the plant. We have cloned a gene in the insect pest that produces one of these ‘effector proteins’ and have shown it can function to overcome one of the new genes for resistance in wheat to Hessian fly. This effector protein causes its effect by being a mimic of a plant protein. These results explain how the pest is able to overcome one of the genes for resistance in wheat. This knowledge will benefit scientists faced with the challenge of ensuring durable resistance to the Hessian fly and will provide for enhanced wheat yields without increased cost to producers and consumers.
Technical Abstract: The genetic tractability of the Hessian fly (HF, Mayetiola destructor) provides an opportunity to investigate the mechanisms insects use to induce plant gall formation. Here we demonstrate that capacity using the newly sequenced HF genome to identify the gene (vH24) that elicits the effector-triggered immunity that is directed against the HF by the resistance gene H24 in wheat (Triticum spp.). vH24 was mapped within a 230-kb genomic fragment near the telomere of HF chromosome X1 containing only 21 putative genes. Among these genes, the best candidate vH24 gene encodes a secretion signal and a type-2 serine/threonine protein phosphatase (PP2C) domain. This gene has a H24-virulence associated insertion in its promoter that appears to silence transcription of the gene in H24-virulent larvae. Candidate vH24 is a member of a small family of genes that encode secretion signals and PP2C domains and belong to the fraction of genes in the HF genome previously predicted to encode effector proteins. Because PP2C proteins are not normally secreted, our results suggest that these are PP2C effectors that HF larvae inject into wheat cells to redirect, or to interfere, with wheat signal transduction pathways.