ABSTRACT
The gene LmR1 controls seedling resistance to the blackleg fungus (Leptosphaeria maculans) and genetic linkage mapping has positioned the locus on linkage group N7 in a region with extensive inter-and intragenomic duplications as well as intrachromosomal tandem duplications (Mayerhofer et al. 2005). Mayerhofer et al. (2005) initiated a physical map of the blackleg resistance locus LmR1 and identifi ed BAC clones carrying the fl anking markers for it. The BAC clones identifi ed have since been sequenced and three tandemly duplicated candidate genes identifi ed, data from this region and homologous regions across the genome will help to elucidate the structure, evolution, and specifi cities of R gene complexes in Brassica species (T. Huebert and I. Parkin, unpubl.). The duplication of the region containing LmR1 on linkage group N7 and the clustering of independent blackleg resistance genes on N7 suggest that the cloning of LmR1 and the subsequent capture of LmR1 homologs may identify additional blackleg resistance genes (Mayerhofer et al. 2005).
