MATING-TYPE SEGREGATION IN CHOANEPHORA-CUCURBITARUM FOLLOWING SEXUAL REPRODUCTION

Zygospore progeny from the cross between + and - isolates of Choanepho ra cucurbitarum consisted of +, -, and +/- types. The + and - zygospor e isolates were stable, giving rise to hyphal fragment cultures and sp orangiospores with the same mating type as their respective parent. Ho wever, the +/- zygospore isolates were unstable, segregating to +, -, and +/- types during asexual propagations. During long-term storage, t he + and - isolates were also very stable, but +/- isolates were not. All the +/- isolates originating from single zygospores, hyphal fragme nts, or sporangiospores produced azygospores, suggesting that azygospo res of this fungus are produced by mating-type heterokaryotic mycelia.