2008 Annual Report 1a.Objectives (from AD-416) Identify genes that contribute to resistance to Fusarium head blight. These genes will be used (in other work) to engineer resistance to FHB, or will be targets for breeder to use in generating varieties with improved FHB resistance. 1b.Approach (from AD-416) Virus-induced gene silencing will be employed to suppress the expression of wheat genes that are candidates for encoding components of pathway providing resistance to FHB. If suppression of a candidate gene results in conversion of resistance to susceptibility, we will have obtained strong evidence that the gene functions in the FHB resistance pathway. 3.Progress Report Program 303 Identification of genes involved in resistance to Fusarium Head Blight (FHB) has been very difficult for two major reasons. First, wheat has at least six copies of most genes, so conventional mutagenesis cannot reveal the affect of the loss of gene function, because there are always other functional copies present that mask the mutation. Second, it is very difficult to transform wheat so T-DNA mutations or T-DNAs expressing RNAi constructs are not feasible. Our approach utilizes virus-induced gene silencing (VIGS) to strongly regulate all copies of chosen genes simultaneously. As virus infection of wheat is very rapid, the results of VIGS experiments can be observed with one month of inoculating the plant with the VIGS construct. Our work has identified several genes as contributing significantly to Fusarium Head Blight resistance in wheat among these are chitinase genes. Independent research (University of Minnesota) has recently shown that engineering over-expression of chitinase does in fact increase resistance of wheat to Fusarium Head Blight, thereby validating our VIGS strategy for identifying genes that play critical parts in Fusarium Head Blight resistance. Very recently, we have seen that a wheat signaling pathway makes a very strong contribution to FHB resistance. Several genes comprise this pathway, and experiments in which three of these genes have been silenced individually, all result in the loss of FHB resistance, indicating that this signaling pathway is essential in the resistance response. If these findings are confirmed, it will provide a novel avenue for engineering Fusarium Head Blight resistance. This accomplishment aligns with National Program 303, Component Three - Plant Disease Resistance Problem Statement 3A Mechanisms of Plant Disease Resistance and 3B Disease resistance in new germplasm and varieties. The ADODR monitoring of this project occurs through very frequent face-to-face meetings with the collaborator, a Purdue University faculty member located in the same building.