SUMMARYThe genevacua(va) is a threshold gene which causes the transition from female sex organs (protoperithecia) to fruit bodies (perithecia). It does not effect spore formation.Vacuaperithecia are sterile and contain only proliferating paraphyses. Thusvaacts independently of the mating type genes (+ and -) which block fertilization in homokaryons and the completion of the sexual cycle. The mating type andvacuagenes are not linked. These findings allow the conclusion that, as in many higher Basidiomycetes, morphogenesis inPodosporais not related to the sexual cycle. This has a practical implication, since in many fungi of industrial value the production phase is correlated with morphogenetic alterations.