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 3H, 4H, 5H, 6H. In the present work, more precise positions of barley Dhn genes were determined using gene-specific PCR and 100 doubled haploid lines developed from a cross of Dicktoo and Morex barley. Dhn10 is located on 3H between saflp106 and ABG4. Dhn6 is at the previously determined position on 4H between SOLPRO and BCD265a. Dhn1 and Dhn2 are at the previously determined 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 to a revised position between BCD265b and saflp218. Dhn3, Dhn4, Dhn7 and Dhn5 each map to the same position on chromosome 6H, suggesting that the previously reported separation of Dhn3, Dhn4 and Dhn5 may reflect limitations in the accuracy of Southern blot data. In addition to clarifying the map positions 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. Received: 11 August 1999 / Accepted: 16 December 1999