Surfing the surface: Hydrophobins on fungal hyphae

Background: Fungal hyphae can grow from the water phase into the air. To achieve that, hydrophobins are covering the fungal cell wall in aerial mycelium. These small proteins are excreted from the growing hyphal tip. The amphipathic proteins refold to form multimers at hydrophobic/hydrophilic interphases. In ectomycorrhizal fungi, hydrophobins are also necessary to achieve multicellular pseudoparenchymatic tissue with rhizomorphs, the hyphal mantle and Hartig’ net. It is still not clear, how the specifically expressed hydrophobins contribute to the hyphal attachment with each other or with the plant cell wall while still not prohibiting nutrient exchange between both partners within the cell-cell contact. While differential expression with different stimuli in the ectomycorrhizal fungus Tricholoma vaccinum could identify mycorrhiza specific and aerial hyphae specific hydrophobins, their role in hyphal contact linked to specific structures could not be elucidated yet. The interaction with the tree root surface also is dependent on hydrophobins. At the same time, the resins in the plant cell walls might change the outcome of the interaction. Therefore, a newly available spruce lacking resin production is to be included in the studies. The status of sugars in the fungus will be included to show nutrient flow.

Project Description: Based on the hypothesis of different structures of hydrophobins with rodlets on aerial hyphae formed by Hyd8 and multimers with ring- or plus-like structure in Hartig’ net, the thesis should identify the proteins in different tissue by mass spectrometry. Using electron microscopy, the multimer structure is to be determined. With transformation experiments, the role of each hydrophobin should be elucidated. To perform knock-out or knock-down experiments, methods like CrispR/Cas or RNAi should be established with the fungus. As a model for different techniques, the white-rot Schizophyllum commune can be used. The inclusion of trees for interaction that are deficient in normal resin production will allow addressing the specific fungus-tree interaction at an early stage of mycorrhization. The different sugars in the fungus vs. mycorrhiza will be addressed to follow the nutrient flow.

Candidate profile: MSc in microbiology and knowledge in molecular biology, knowledge with ectomycorrhizal is advantageous.