Stage-specific cellular localisation of two hydrophobins during plant infection by the pathogenic fungus Cladosporium fulvum

Hydrophobins are central to developmental processes of filamentous fungi. HCf-1 and HCf-6 are two of the six hydrophobins identified in the plant pathogenic fungus Cladosporium fulvum. We have fused the viral epitope V5 to HCf-1 and HCf-6, introduced the recombinant genes into C. fulvum strains that lack the two genes, and localised the tagged proteins by immunofluorescence microscopy. HCf-1 V5 is abundant on conidia and aerial structures formed in vitro and emerging from disease lesions on infected tomato plants. This is consistent with the proposed function of HCf-1 in aerial development and dissemination of conidia. HCf-6 V5 is secreted onto the growth substrate by the hyphae and during invasion of plant tissues, which suggests a function in adhesion and infection. This was not supported by the phenotypic analysis of ΔHCf-6 strains. Hydrophobins may play distinct roles due to precisely regulated spatial localisation during infection-related development of C. fulvum. Index descriptors: hydrophobin, epitope-tag, immunocytochemistry, Cladosporium fulvum