Genetics of Ustilago violacea. VI. Characterization of White and Yellow Strains by Recombination and Complementation

Abstract

Ten wild collections of Ustilago violacea gave 18 white strains, and 12 wild collections gave 12 yellow strains. One of seven white intracollection crosses produced white-and-pink-sectored teliospore colonies and pink disomic teliospore colonies. Eleven of 27 white intercollection crosses yielded sectored teliospore colonies, pink disomic teliospore colonies, or both types of colonies. Eleven yellow intercollection crosses gave only yellow teliospore colonies, and 16 intercollection crosses gave a number of yellow-and-white-sectored or white teliospore colonies. These observations were explained by proposing (1) crossing over between mutant sites in the white (w) locus or complementation for mutations in the w locus and (2) spontaneous mutations in the w+ locus for certain yellow (y) strains to produce yw nuclei in cells of the infectious dikaryotic hypae. Recombination or complementation at the w locus for the wild white strains indicates nucleotide polymorphism for this locus.