Cloning and characterization of hydrophobins-encoding cDNAs from the ectomycorrhizal Basidiomycete Pisolithus tinctorius

Major alterations of fungal gene expression are induced by the development of ectomycorrhiza, a symbiosis between tree roots and filamentous fungi. Several cDNAs corresponding to highly expressed transcripts of the Basidiomycete Pisolithus tinctorius (Pt) were isolated from symbiotic tissues, Two of these abundant transcripts (hydPt-1 and hydPt-2) encoded polypeptides belonging to the hydrophobin (Hyd) family, a group of small cysteine-rich fungal proteins involved in morphogenesis and plant-fungus interactions. As shown for other Hyd, the hydPt-1 and hydPt-2 mRNAs were barely detectable in mycelium grown in liquid culture and highly accumulated in aerial hyphae. In addition, these transcripts were also abundant in Eucalyptus globulus-Pt ectomycorrhiza in early stages of differentiation, during the colonisation of roots.