Independent Inheritance of Genes Governing Virulence and the Production of a Polypeptide in Ustilago hordei*

Detergent soluble polypeptides from teliospores of Ustilago hordei were examined by two-dimensional isoelectric focusing-polyacrylamide gel electrophoresis. A relatively prominent polypeptide (M.W. 28,000, P¹ 6.8) was found in extracts of teliospores from two isolates that were avirulent on the barley cultivar ‘Plush’ but was not detected in extracts from two isolates that were virulent on this cultivar. The polypeptide was also detected in extracts from teliospores of an F₁, hybrid between one of the virulent and one of the avirulent isolates. Haploid cultures from five meiotic tetrads, isolated from the F₁ hybrid, were backcrossed to haploids from the virulent parent to determine the pathogenicity of each strain. The polypeptide segregated among the 20 progeny as if under the control of a single, dominant allele. The gene governing virulence on ‘Plush’ was not linked to the gene governing the segregating polypeptide.