on cellular degenerative phenomena, our research recently led to a better
comprehension of various aspects of fungal biology. We chose as a
"model" organism, the filamentous fungus Podospora
anserina because this ascomycete is easy to study in the lab. Its
complete sexual cycle lasts one week. P. anserina can be grown on
well-defined and simple media and last but not least, screening or making
mutants in this organism is very easy. These mutants can then be analyzed up to the molecular level thanks to the
possibility to transform with DNA P. anserina cells. Recently, we
have extended the number of fungal species (coprinus,
on which we perform experiments.
Like most fungi P. anserina
alternate between a mycelial form and a sporal form:
The mycelial form is the trophic phase. It
possesses all the characteristics of the euascomycete
mycelium: apical extension, septation and
anastomosis. However, during growth, P. anserina presents two cell
degenerative syndromes: Senescence
studied for now more than 40 years and Crippled
Growth that we discovered in the lab. These two degenerations are under
the control of non-conventional genetic elements, which are
"cytoplasmic and infectious determinants". Such elements are very
widespread in fungi and are not genetic elements (plasmides,
virus...) but rather epigenetic elements. Moreover, in nature, P.
anserina grows on herbivore dung, where many other fungal species also
inhabit. We have shown that P. anserina mycelium presents a defence
mechanism to cope with competitors.
The sporal form is obtained solely after meiosis
as ascospores that are used for dissemination. These ascospores are
produced in a differentiated structure (the perithecium) during sexual
reproduction. The development of perithecia is controlled by numerous
factors including starvation and light. Once produced, ascospores are
ejected in an active manner outside the perithecium. They do not germinate
spontaneously but require a stimulus (the passage through the digestive tractus of an herbivore) that is easily recreated in
goal is to understand how the different steps of P. anserina cycle
are regulated. We focus on the roles
of the three MAP kinase cascades resent in P. anserina genome
because they are required at various moments of the life cycle.
Additionally, we study NADPH oxidases. These enzymes of the plasma membrane
generate ROS, which have a role in signalling. We also recently showed that
these signalling cascades also regulate the way the fungus degrades plant
biomass. Our research thus also focuses on how fungi degrade dead plant
materials. More specifically, we seek to understand how cellular
differentiations enable mycelia to penetrate their substrate and how they
enable to scavenge efficiently nutrients.
To know more look at our publications!!!