High-Resolution Genetic and Physical Mapping of the Eastern Filbert Blight Resistance Region in ‘Jefferson’ Hazelnut (Corylus avellana L.)

Eastern filbert blight (EFB), caused by the pyrenomycete (Peck) E. Müller, is a devastating disease of European hazelnut ( L) in the US Pacific Northwest. A dominant allele at a single locus from the obsolete pollenizer ‘Gasaway’ confers a high level of resistance to EFB. To identify the gene responsible for resistance, we initiated map-based cloning efforts in a population of 1488 seedlings that segregated for resistance. Chromosome walking was initiated using primers designed from eight previously identified random amplified polymorphic DNA markers linked to resistance. The bacterial artificial chromosome (BAC) library was screened using the primer pairs in a polymerase chain reaction–based pooling and subpooling strategy. Here, we report construction of a high-resolution genetic map and a physical map of the resistance region. Further, we sequenced BACs in the resistance region and identified and annotated the coding sequences. In seven contigs