Mycorrhiza : mechanisms and management

Team Leader : Daniel WIPF

The research focus of our group is the understanding of the interactions between plants and microorganisms (e.g. symbiotic fungi, oomycetes …) that contribute to the improvement of the plant fitness (nutrition, defense/resistance to pathogens or to biotic stress such as drought or heavy metals). Our research works is organized at various integrating levels.

At the plant cell level, we are interested in the early signaling pathways triggered by molecules from microorganisms (mutualistic and pathogenic). Our work aims to explore the lateral segregation of lipids and proteins (e.g NADPH producer, transporters) into plasma membrane domains and to identify the cell determinants of such segregation in order to understand its role in the signaling pathways. In addition, we are analyzing the role of intracellular trafficking to and from the plasma membrane, in particular the clathrin-mediated endocytosis, in the signaling. Finally, we are interested in knowing how signaling lipids and reactive oxygen species produced by NAPHP oxidases contribute to the early steps of defense signaling.

At the biotrophic interface, our research work focuses on the arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and the most common group of mycorrhizal fungi of the phylum glomeromycota. Our interests are in understanding the establishment and functioning of the mutualistic symbiosis mainly at the nutrient exchange level (transportome). We particularly aim at identifying and selecting sugar transporters from plant, and analyzing sugar flows along the plant and through the plasma membrane that may impact in the outcome of the plant-microbe interaction. We are also interested in fungus monosaccharide transporters that would allow direct uptake of sugars from the soil. Moreover, we also study AM formation in combined phosphate and nitrogen limited conditions allowing an altered profile of plant defense genes, very likely through the activation of NADPH oxidases.

Consequently, we also investigate how to actually use the mutualistic interaction practically in the field for optimizing the provided ecosystemic services. Indeed, establishment of an AM community through mycelia network can significantly increase nutrient absorption in starved soils, as well as water absorption and resistance to pathogens or heavy metals, therefore allowing the reduction of the application of chemical fertilizers and pesticides.

Our main model for signaling pathway and defense in pathogenic interaction is tobacco cells elicited by cryptogein secreted by the oomycete Phytophthora cryptogea. Our main symbiosis model is the association Medicago truncatula/Rhizophagus irregularis, but we also work on various plants of agronomical interest such as grape.