2010 Annual Report 1a.Objectives (from AD-416) The objective of this research is to increase understanding of the molecular basis of host resistance and insect virulence in the wheat/Hessian fly system. The long-term goal is to develop strategies for durable resistance to this important insect pest. 1b.Approach (from AD-416) The molecular basis of host resistance will be approached by cloning and characterizing a wheat resistance gene for Hessian fly known as Hdic from Triticum turgidum subsp. dicoccum. This resistance gene resides in a region of wheat chromosome 1A that contains at least 14 other resistance genes for Hessian fly. Candidate genes will be identified by fine mapping and sequencing of BAC contigs. Candidate genes will be tested initially by gene silencing using RNA interference. A cosmid library from the donor of Hdic will be constructed to isolate the resistance allele. Expression vectors will be constructed for the candidate gene and tested for ability to confer resistance to Hessian fly. The molecular basis of Hessian fly virulence/avirulence will be approached by determining the functions of secreted salivary gland proteins (SSGP) of Hessian fly in virulence or avirulence to wheat. Differential gene expression of SSGPs will be tested in different biotypes of Hessian fly using a custom-designed microarray. Candidate genes for virulence or avirulence effectors will be identified. Candidate genes will be tested by gene silencing using RNA interference. 3.Progress Report The objective of this research is to increase understanding of the molecular basis of host resistance and insect virulence in the wheat/Hessian fly system. Progress continued on the effort to clone the wheat resistance gene Hdic, which confers resistance to Hessian fly. Candidate genes have been identified and are being tested. We discovered a rapid mobilization of membrane lipids in resistant plants in response to Hessian fly attack. Mobilized lipids are likely converted into defense signaling molecules and components for cell wax. This discovery suggests that lipid mobilization and conversion might be a necessary molecular basis for plants to be resistant to Hessian fly. This work is among the first studies for systematic analysis of membrane lipids in plant defense. Progress on this agreement is monitored by regularly discussing program goals, approaches, and results (teleconference, email) and by reviewing annual accomplishments reports.