Differentiation and melanin production in hyaline and pigmented strains of Microdochium bolleyi

The effect of various compounds on growth, melanin biosynthesis and cell differentiation was studied in a hyaline (SH25) and a pigmented (SH25B) strain of Microdochium bolleyi. Dark pigment production by the hyaline strain was induced by the presence of DOPA and indole in the medium, both of which are intermediates in the tyrosine pathway of melanin biosynthesis. These substrates also induced conidia and chlamydospore production, structures which were not normally seen in the hyaline strain. The systemic fungicide, tricyclazole, inhibited melanin synthesis in the pigmented strain but not the development of chlamydospore-like cell structures.