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Oral: Host Plant Resistance


Utilizing mapping-by-sequencing to identify the Dominant Net Form Net Blotch Resistance Gene from Barley Line CI 5791
P. TAMANG (1), R. Brueggeman (1), J. Richards (1), T. Friesen (2) (1) North Dakota State University, U.S.A.; (2) Cereal Crops Research, USDA, U.S.A.

Net form net blotch (NFNB) caused by Pyrenophora teres f. teres is a destructive foliar disease in barley growing regions worldwide. The diverse pathogen populations and complex host-parasite interactions occurring in this pathosystem has hindered breeding efforts. A dominant NFNB resistance gene identified on chromosome 6H in the line CI5791, designated RptCI5791, provides resistance to diverse isolates and is tightly linked to the dominant susceptibility locus Spt1. CI5791 lacks Spt1 as we were unable to amplify any allelic variants of Spt1. Thus, we hypothesize the high level of resistance in CI5791 is due to the dominant resistance gene RptCI5791 coupled with the absence of the dominant susceptibility locus Spt1. To further identify and characterize this broad-spectrum resistance, we used a forward genetics approach by g-irradiation and identified five putative mutants CI5791-γ3, -γ6,7,8, and9 that are susceptible. We are utilizing the barley SEQCAP exome capture array (Nimblegen) and Illumina sequencing to identify the gene using a mapping-by-sequencing method. Mutated gene/s that map to the centromeric region of barley chromosome 6H will represent a strong candidate RptCI5791 gene. However, the possibility still exists that alleles of the CI5791 gene may not be present in the lines used in the exome capture, which would result in a failure to identify the gene. In this case we will continue pursuing the tried and true positional cloning approach.