Construction of a YAC library from barley cultivar Franka and identification of YAC-derived markers linked to the Rh2 gene conferring resistance to scald (Rhynchosporium secalis)

The Rh2 resistance gene of barley (Hordeum vulgare) confers resistance agai nst the scald pathogen (Rhynchosporium secalis). A high-resolution genetic map of the Rh2 region on chromosome 1 (7H) was established by the use of mo lecular markers. Tightly linked markers from this region were used to scree n existing and a newly constructed yeast artificial chromosome (YAC) librar y of barley cv. Franka composed of 45 000 clones representing approximately two genome equivalents. Corresponding YAC clones were identified for most markers, indicating that the combined YAC library has good representation o f the barley genome. The contiguous sets of YAC clones with the most tightl y linked molecular markers represent entry points for map-based cloning of this resistance gene.