Genetic analysis of adult plant resistance to Puccinia hordei in barley

P>Genetic studies were conducted to determine the number of genes conferring adult plant resistance (APR) to Puccinia hordei in eight barley genotypes and to determine their relationship with each other. Field testing of segregating populations at two field sites indicated that the genotypes 'Vada', 'Nagrad', 'Gilbert' and 'WI3407' each carried one gene for APR to leaf rust. Genotypes 'Patty', 'Pompadour''Athos' and 'RAH1995' showed digenic inheritance of APR at one field site and monogenic inheritance at the second. One of the genes identified in each cultivar provided high levels of APR and was effective at both field sites. The second APR gene was effective only at one field site, and it conferred low levels of APR. Tests of allelism between resistant genotypes confirmed a common APR gene in all with the exception of 'WI3407', which was genetically distinct from the gene common in 'Vada', 'Nagrad', 'Patty' and 'Pompadour'.