Project Number: 3602-22000-016-03
Project Type: Specific Cooperative Agreement

Start Date: Sep 20, 2007
End Date: Aug 31, 2012

Objective:
The SCA objectives are to characterize the response of wheat undergoing dual infestation by both virulent and avirulent Hessian fly larvae, a situation common in the wheat field. Deliverables include mRNA and protein sequences, expression data and protein function. In addition detailed information will be generated that determines the timing and physical proximity of the two infestation events in order for the virulent larvae to rescue the avirulent larvae.

Approach:
In wheat fields, Hessian fly populations generally consist of a variety of virulent and avirulent genotypes. A phenomenon known as ¿obviation of resistance¿ can occur if both larval genotypes co-inhabit the same plant, resulting in survival of larvae that should have been killed. This has important ramifications for durability of resistance. But the timing of infestations and the gene expression consequences to the plant have not been studied. The first phase of the project requires very carefully timed infestations in which the virulent larvae are placed on the plants 0 through 8 days before avirulent larvae are placed on the plants (also the reverse with avirulent larvae placed first). This will determine the required window of overlap in order for the avirulent larvae to be rescued and thus survive on a plant that should kill them. Subsequent phases include molecular techniques such as micro-arrays and quantitative real-time PCR to determine whether virulent larvae block the recognition or turn off plant defenses that would lead to death of the avirulent larvae. Gene silencing may be used to inhibit gene products that are necessary for obviation of resistance.