The Trichoderma reesei hydrophobin genes hfb1 and hfb2 have diverse functions in fungal development

Hydrophobins are fungal self-assembling proteins. Here, the hydrophobin genes hfb1 and hfb2 were deleted in Trichoderma reesei and their biological roles studied. Our results suggest that HFBI has a role in hyphal development and HFBII in sporulation. Sporulating colonies of the Δhfb2 strain were wettable and sporulation was only 50% of the parent strain. Colonies of Δhfb1 showed wettable and fluffy phenotype. In shaken liquid cultures, the hyphae of Δhfb1 were thinner and biomass formation was slower compared to the parent strain while in static liquid cultures no aerial hyphae were formed. Expressing the Schizophyllum commune hydrophobin SC3 in the Δhfb1 strain restored the formation of aerial hyphae.