Map locations of barley Dhn genes determined by gene-specific PCR

We previously identified 11 unique barley Dhn genes and found, using wheat- barley addition lines, that these genes are dispersed on four chromosomes 3 H, 4H, 5H, 6H. In the present work, more precise positions of barley Dhn ge nes were determined using gene-specific PCR and 100 doubled haploid lines d eveloped from a cross of Dicktoo and Morex barley. Dhn10 is located on 3H b etween saflp106 and ABG4. Dhn6 is at the previously determined position on 4H between SOLPRO and BCD265a. Dhn1 and Dhn2 are at the previously determin ed position on 5H between mR and saflp172. The Dhn locus previously called Dhn4a on barley 5H or Dhn2.2 on T. monococcum 5A is in fact Dhn9 and maps t o a revised position between BCD265b and saflp218. Dhn3, Dhn4, Dhn7 and Dhn 5 each map to the same position on chromosome 6H, suggesting that the previ ously reported separation of Dhn3, Dhn4 and Dhn5 may reflect limitations in the accuracy of Southern blot data. In addition to clarifying the map posi tions of these important stress-related genes, these results illustrate the advantage of gene-specific probes for the mapping of individual genes in a multi-gene family.