Immunolocalization of hydrophobin HYDPt-1 from the ectomycorrhizal basidiomycete Pisolithus tinctorius during colonization of Eucalyptus globulus roots

The immunolocalization of one of the hydrophobins of Pisolithus tinctorius (HYDPt-1) is reported. Hydrophobin proteins play key roles in adhesion and aggregation of fungal hyphae, and it is already known that formation of ectomycorrhizas on eucalypt roots enhances the accumulation of hydrophobin mRNAs in the mycelium of Pisolithus tinctorius. Purification of SDS-insoluble proteins from the mycelium of P. tinctorius showed the presence of a 13 kDa polypeptide with properties of class I hydrophobin. Polyconal antibodies were raised against a recombinant HYDPt-1 polypeptide, and these were used for immuno fluorescence-coupled transmission electron microscopy. HYDPt-1 is a cell wall protein located at the surface of the hyphae with no preferential accumulation in the fungal cells of the different tissues of the ectomycorrhiza (i.e. extraradical hyphae, mantle or Hartig net).