Mating reactions of pigmented and non-pigmented isolates of Arthroderma uncinatum.

Abstract

Keratinomyces ajelloi the conidial state of Arthroderma uncinatum has 2 colonial forms — one producing dark vinaceous-red pigment and the other devoid of diffusible pigment. Twenty-one isolates of this fungus, including 2 pairs of + and - test strains, were crossed with each other in all possible combinations on soil-hair medium. Of the 13 pigmented isolates 5 were + mating type, 5 were — mating type, 2 were self-fertile, and 1 was incompatible. Of the 8 nonpigmented isolates, 5 were + mating type, and 3 were —. Of 80 crosses between + and - isolates, only 6 were abundantly fertile, and 44 were completely sterile. Two of the + and 3 of the - isolates were strong reactors, being fertile with most of the isolates of the opposite mating type. The rest of the isolates showed a high degree of incompatibility with each other. The compatibility of all the 8 non-pigmented isolates with the pigmented test strains indicates that lack of pigment does not denote a separate taxon.