Implication of a MADS box protein (MCM1) for spontaneous perithecium development in Podospora anserina

The ascomycete Podospora anserina is a heterothallic filamentous fungus found in herbivore dungs, commonly used in laboratories as a model system, and for which the complete life cycle is reproducible in vitro. The main objective of our team is to better understand the global process of the development of fruiting body, named perithecia, induced by fertilization. In this context, three mutants, named pfd3, pfd9 and pfd23 (for « promote fruiting body developement ») obtained by UV mutagenesis, were selected in view of their abilities to promote barren perithecium development without fertilization. By complete genome sequencing of pfd3 and pfd9 mutants, we identified point mutations in the MCM1 gene and validated this gene by complementation. We also showed that the pfd23 mutant was mutated in MCM1. MCM1 proteins are MADS box transcription factors that control diverse developmental processes in plants, metazoans, and fungi. Here, we present the complete functional characterization of the three pfd mutants, as well as that of the deleted strain. In particular, we showed that ∆MCM1 and pfd3 were sterile and that the development of spontaneous perithecia needed the presence of wild-type nuclei in the mycelium, whereas pfd9 et pfd23 were able by themselves to spontaneously produce perithecia.