Homokaryotic Fruiting in the Bipolar-Incompatible Ascomycete Podospora Anserina

SUMMARY

The gene vacua (va) is a threshold gene which causes the transition from female sex organs (protoperithecia) to fruit bodies (perithecia). It does not effect spore formation. Vacua perithecia are sterile and contain only proliferating paraphyses. Thus va acts independently of the mating type genes (+ and -) which block fertilization in homokaryons and the completion of the sexual cycle. The mating type and vacua genes are not linked. These findings allow the conclusion that, as in many higher Basidiomycetes, morphogenesis in Podospora is 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.