Matériaux et Biomatériaux innovants

 

Génétique et Epigénétique des Champignons

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L'équipe GEC fait partie du Laboratoire Interdisciplinaire des Energies de Demain (LIED), UMR 8236

Responsable de l'équipe:
Professeur Philippe Silar

Tel: (33) 1 57 27 84 72

E-mail:philippe.silar@univ-paris-diderot.fr

 

 

RESEARCH PROGRAM

 

Initially focused 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, penicillium, chaetomium...) 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 the lab.

               Our 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!!!