Genetics of resistance to powdery mildew in some Ethiopian barleys

Abstract

The genetics of the resistance of sixteen Ethiopian barley lines to various powdery mildew isolates was studied. The resistance of most of these lines to individual isolates is conditioned by single genes. Four of the lines have genes in the ml-o locus. Gametic selective advantage for the spontaneous ml-o mutants was observed and the prevalence of ml-o mutants in barley land race populations from Ethiopia is discussed. The gene Ml-(La) from H. distichan var. laevigatum was found linked to the ml-o locus in some crosses, but not in other crosses. Twelve of the lines give incomplete resistance and the spectra of resistance of these lines indicated that most of the lines possess more than one gene for mildew resistance, but only single genes were detected in the inheritance studies by using the appropriate isolates that overcome the additional genes. The breeding value and the possible durability of their resistance are discussed in view of the frequent occurrence of incomplete resistance in barley land race populations.