Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Regulation Of Wheat Genes In Response To Attack By The Hessian Fly

Marcelo P. Giovanini¹ , David P. Puthoff^{2, 3} , Herbert W. Ohm¹ , Christie E. Williams ^{2, 3, 4}

¹  Department of Agronomy, Purdue University, 915 W. State St, West Lafayette, IN 47907

²  USDA-ARS Crop Production and Pest Control Research Unit, West Lafayette, IN 47907

³  Department of Entomology, Purdue University, 901 W. State St, West Lafayette, IN 47907

⁴  Corresponding author: cwilliams@purdue.edu FAX: 765-494-5105

Successful establishment of feeding sites by virulent Hessian fly larvae results in stunting of the susceptible plants of the wheat host. However, when avirulent larvae attempt to feed at the base of wheat seedlings, resistance responses lead to death of the first instar larvae, and nutritive tissue that forms the feeding site does not develop. The interactions of Hessian fly and wheat are dictated by a gene-for-gene relationship. However, classical PR (Pathogenesis Related) protein-encoding genes show only minor involvement in the molecular response, whereas a typical oxidative burst and associated HR (Hypersensitive Response) are not elicited upon avirulent fly attacks on resistant wheat plants. Mechanisms of resistance and susceptibility at the molecular level have not been elucidated. In order to characterize these interactions, we have cloned several wheat genes that are responsive to virulent and avirulent Hessian fly larvae. During compatible interactions, genes encoding several proteins that may function in formation of nutritive tissue (Hfr-2, a pore forming protein; GST, a putative auxin binding glutathione S-transferase; sorbitol transporter and connective tissue growth factor) were all significantly up-regulated in susceptible plants compared with the uninfested control. A gene encoding a lipid transfer protein was down-regulated during the compatible interactions.
During incompatible interactions, there was accumulation of transcripts from two genes with defense functions (wheat germ agglutinin and a flavanone-3 hydroxylase (F3H) gene). F3H were also up-regulated at a later time during susceptibility. Studies that address the involvement of these genes in interactions with Hessian fly larvae will be presented.