One of the aims of my dissertation was to investigate the morphological study of colour mutant variants of the M. fructicola type strain (CBS 8853T). We wanted to control the pigment production of previously selected and nitrosoguanidine-treated versions of the type strain. We wondered if they showed any discrepancies compared to the original type strain.As a first step in the morphological studies, the mutant strains were subjected to microscopic analysis, in which similar cell morphology was observed as previously described by Kurtzman and Droby (2001). After completion of the physiological studies, the coloured mutant strains were subjected to molecular studies. To perform molecular studies, we first designed primers for the sequences of PUL1-4 genes using SnapGene software.