Inheritance of Resistance to Loose Smut of Oat. Roy D. Wilcoxson, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. David J. Miller, and Deon D. Stuthman. Former Research Assistant, and Professor, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108. Plant Dis. 77:822-825. Accepted for publication 21 December 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0822.

The percentage of plants infected with loose smut (Ustilago avenae) was determined in oat (Avena sativa) parental cultivars and lines and in progenies after kernels were inoculated with water suspensions of teliospores by a vacuum procedure. Inheritance of resistance was studied with F₄ populations of three crosses. In cross Ogle/ND 820559 (susceptible/moderately resistant), the distribution of F₄ progenies appeared bimodal, with more of the progeny clustered around ND 820559 than around Ogle. Twenty-one percent of the F₄ lines displayed fewer infected plants than the resistant parent. In Don/Starter (resistant/resistant), the distribution of F₄ lines was skewed toward low incidence of infection, with many lines more susceptible than either parent. This suggested that resistance was probably conditioned by at least two genes. In Ogle/MN 85230 (susceptible/resistant), the distribution of F₄ lines appeared multimodal, with many lines similar to MN 85230, the resistant parent. The reaction of F₄ lines was verified by testing F₅ lines. Realized heritability, estimated from the Ogle/ND 820559 cross, was 0.93. The incidence of loose smut in Ogle and ND 820559 was not reduced by reselection.