Isolation and characterization of novel biomolecules during the mutualistic interaction between Piriformospora indica and Arabidopsis thaliana The endophytic fungus Piriformospora indica can form beneficial interaction with many different plant species including Arabidopsis thaliana. This interaction has similarities to mycorrhiza can improve the plant fitness and can result in a higher biomass production. This work was focused on the perception of a novel signalling molecule cellotriose and the identification of symbiosis specific secreted proteins.