Inheritance of Resistance to Pyrenophora graminea in Barley. Mohammed Boulif, Professor, Department of Plant Pathology, National School of Agriculture, Meknes, Morocco. Roy D. Wilcoxson, Professor, Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108. Plant Dis. 72:233-238. Accepted for publication 11 October 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0233.

Barley cultivars and lines adapted for cultivation in Morocco and considered to be resistant or susceptible to the stripe disease caused by Pyrenophora graminea were crossed and progenies were tested for resistance to three virulent isolates of the pathogen obtained in Morocco. Progenies in the F₁, BC₁, BC₂, F₂, and F₃ generations were tested with isolate 17. In the cross Minnesota 23 × Atlas 68, resistance of Minnesota 23 was conditioned by a single dominant gene. This also was true in the cross Minnesota 23 × Merzaga 077. In the cross Arig 8 × Merzaga 077, resistance was heritable, but its genetic control was not determined because of the intermediate level of resistance in Arig 8. In the cross CI 9737 × Merzaga 077, resistance of CI 9737 was conditioned by two genes, one of which appeared to have a recessive epistatic effect on the other. In the cross CI 9737 × Atlas 68, resistance was controlled by recessive genes, but the number could not be estimated. In the cross Arig 8 × Atlas 68, resistance was also controlled by recessive genes, but again gene numbers could not be estimated. Progenies of Minnesota 23 × Atlas 68 were tested for resistance to P. graminea isolates 16 and 25, which were more virulent than isolate 17. With isolate 16, resistance of Minnesota 23 appeared to be due to two recessive genes with cumulative effects. With isolate 25, the resistance of Minnesota 23 probably was governed by several genes.