A COLOR MUTATION, ITS INHERITANCE, AND THE INHERITANCE OF PATHOGENICITY IN PUCCINIA GRAMINIS PERS

Seven lots of teliospores of Puccinia graminis Pers. gave rise to mutant white infections on barberry. Cultures heterozygous for the white mutation produced equal numbers of white and normal orange infections indicating that a single mutation caused the absence of color. White pycnial infections fertilized with nectar from normal pycnial infections, and normal infections fertilized with nectar from white infections produced normal aecia, but white infections fertilized with nectar from white infections produced white aecia. White aecia gave rise to greyish-brown uredial cultures. A single dominant gene governed virulence on the varieties Arnautka and Mindum and it appeared to be linked to the locus governing color. Virulence on lines of the variety Marquis carrying genes Sr8 or Sr9a was governed by single recessive genes. Tests of significance indicated that virulence on the line carrying Sr7 was linked with virulence on the line carrying Sr10, and virulence on Lee with virulence on Sr10.