Mating type segregation inChoanephora cucurbitarumfollowing sexual reproduction

Abstract

Zygospore progeny from the cross between + and − isolates of Choanephora cucurbitarum consisted of +, −, and ± types. The + and − zygospore isolates were stable, giving rise to hyphal fragment cultures and sporangiospores with the same mating type as their respective parent. However, the ± zygospore isolates were unstable, segregating to +, −, and ± types during asexual propagations. During long-term storage, the + and − isolates were also very stable, but ± isolates were not. All the ± isolates originating from single zygospores, hyphal fragments, or sporangiospores produced azygospores, suggesting that azygospores of this fungus are produced by mating-type heterokaryotic mycelia. Keywords: azygospore, Choanephora cucurbitarum, germsporangiospore, germsporangium, zygospore germination.