Molecular mapping of a new gene in wild barley conferring complete resistance to leaf rust (Puccinia hordei Otth)

A dominant gene conferring resistance to all known races of Puccinia hordei Otth was identified in two accessions of Hordeum vulgare ssp. spontaneum. Using restriction fragment length polymorphism (RFLP) markers the gene was mapped on chromosome 2HS in doubled-haploid populations derived from crosse s of both accessions to the susceptible cultivar L94. Until now, complete l eaf rust resistance was not known to be conditioned by genetic factors on t his barley chromosome. Therefore, the designation Rph16 is proposed for the gene described in this study. A series of sequence tagged site (STS) and c leaved amplified polymorphic sequence (CAPS) markers were generated by conv ersion of RFLP probes which originate from the chromosomal region carrying the resistance gene. Two PCR-based markers were shown to co-segregate with the Rph16 gene in both populations thus providing the basis for marker-assi sted selection.