Rhythmic mycelial growth in Podospora anserina

Abstract

1. A model is presented which may help to elucidate the growth pattern of the clock-mutant zonata of Podospora anserina. The model consists of two main parts. The superficial hyphae grow with an increasing change of the branching pattern and a decreasing rate of elongation. The submerged hyphae do not exhibit this development for they are growing under oxygen deficiency. They emerge in front of the retarding superficial hyphae and thus initiate the next growth band. 2. The model was supported by the following results: Absence of oxygen from the surface of the cultures prevented the rhythmic growth; mycelia separated from the medium by a cellophane cover produced no zonations or rings and grew at a decreasing rate; the presence of a sufficient supply of oxygen in the total medium, as achieved in vigorously shaken cultures, prevented the formation of the successive growth phases. 3. Further evidence for this model was found in the literature. Various aspects of this rhythmic type of growth in other fungi are explained in terms of this model.