Inheritance of resistance to Puccinia hordei in cultivated and wild barley

The inheritance of resistance to Puccinia hordei in Several accessions of Hordeum vulgare and H. spontaneum was studied using leaf rust isolates whose combination of virulence genes would overcome resistance due to Rph1-Rph12. The results from this study indicated the presence of the Rph3 resistance gene in cultivar Aim. This gene was dominant for resistance to isolate ND8702 but recessive for resistance to ND89-3. Allelism tests suggested that the Rph3 allele occurred in a high frequency in barley originating from Egypt and the Mediterranean region. The following accessions of H. vulgare possess gene(s) that are likely different from Rph1-Rph12: Cl 10506 (one dominant gene), PI 531849 (one dominant gene), and PI 531990 (a recessive gene in addition to Rph3). The H. spontaneum accessions were more diverse than the H. vulgare accessions, in both the number of genes for resistance to P. hordei and the types of interactions with rust isolates. Most of the H. spontaneum accessions tested had more than one resistance gene, with both dominant and recessive genes being common.