The inheritance of resistance to Puccinia hordei G. Otth in 14 spring barley accessions was studied in the greenhouse. Progeny from crosses of the resistant accessions with the susceptible cultivars Moore and Larker and crosses to barley host-differential lines with known Rph genes for resistance were evaluated for their reaction to P. hordei race 30. Progeny of crosses among resistant accessions also were evaluated for reaction to race 30. Resistance was found to be governed by Rph 3 (independently or in combination with other genes) in 10 of the barley accessions. Two of the accessions possess Rph 9. One accession has both Rph 3 and Rph 9, while two accessions possess Rph 3 and an unknown Rph gene. In one case, an unknown recessive gene governed resistance to race 30. Among all accessions, Rph 3 was the most common resistance gene.

The inheritance of leaf rust resistance in nine accessions of Hordeum vulgare L. subsp. spontaneum, a wild relative of barley, will be studied this spring. Genetic populations from crosses between the wild accessions and the cultivar Barsoy have already been developed. Resistance from the nine H. vulgare accessions has also been backcrossed into Barsoy (an adapted winter barley). Following another year of advancement of these populations, we will begin to select leaf rust resistant isogenic lines to be released as germplasm.