ABSTRACT
Podospora anserina is a filamentous ascomycete naturally growing on the dung of herbivores. This substrate dries out very fast and is therefore a suitable nutritional resource for only a very limited time. To survive, P. anserina is forced to propagate efficiently in a short time. Propagation proceeds via a sexual cycle (Fig. 1) giving rise to the formation of meiospores, the so-called ascospores. These spores are generated in a special sporangium, the ascus. Many asci are produced in one fruiting body, the perithecium. Mature ascospores are shot out of the ascus and the perithecium and adhere to surrounding herbage. After ingestion by a herbivore and after passing through its intestine, they germinate on dung and give rise to the formation of a new vegetation body, a mycelium. Under natural conditions senescence of the mycelium does not play a role because it is destroyed as the result of the unfavorable changes of the habitat before reaching the senescent phase. It appears that, in accordance with the “disposable soma theory of aging” [1-3], the adaptation to the special ecological niche has led to the evolution of a life cycle in which most of the available energy is expended into an efficient and fast reproduction and only little energy into cellular maintenance functions (e.g., defense and repair).
