Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 11/3/2007
Publication Date: 1/12/2008
Citation: Harris, M., Freeman, T., Williams, C.E., Subramanyam, S. 2008. How does wheat resistance mediated by H genes prevent manipulation of cell development by Hessian fly larvae?. Plant and Animal Genome Conference Proceedings. Abstract No. W378. Interpretive Summary:
Technical Abstract: The larva of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), induces a gall nutritive tissue in susceptible wheat Triticum aestivum L. The nutritive tissue acts as a resource sink within the wheat seedling and causes serious crop losses. Hessian fly populations have been successfully controlled by the deployment of single H genes; however, the mechanism of H gene resistance is not known. We used various imaging techniques (SEM, TEM, light microscopy and video) and four wheat genotypes expressing H6, H9, H13 or H26 to explore the hypothesis that larval attack of H gene-resistant wheat triggers an induced defense that prevents the creation of the larval nutritive tissue. Attack of resistant wheat begins with the larva moving on the abaxial leaf surface, using its tiny paired mandibles (each 1 µm in diameter) to penetrate the outer cell wall of epidermal cells. Epidermal cells underneath the larva showed a range of responses, e.g. an accumulation of endoplasmic reticulum, numerous small vesicles associated with Golgi bodies, an increase in the surface area of the plasma membrane, a separation between the plasma membrane and the cell wall, and a thickening of the outer cell wall. In contrast to larvae attacking susceptible plants, larvae attacking resistant plants did not settle at attack sites and did not grow before dying. No evidence of a nutritive tissue was found in resistant seedlings. Results are discussed within the context of recent discoveries about wheat defense-response genes and the gene-for-gene model of wheat-Hessian fly interactions.