Fractal dimension and shape parameters of asexual Fusarium spores from selected species: Which species can be distinguished?

Fungi of the genus Fusarium are prominent plant pathogens producing various toxic secondary metabolites. Digital microscopic images were taken from the asexual spores of Fusarium avenaceum, E cerealis, E culmorum, F. graminearum, F. poae, F. oxysporum, F sambucinum, and F. verticillioides. The asexual spore type formed first on Potato Dextrose Broth (PDB) medium was used. Fusarium avenaceum, cerealis, F. culmorum, E graminearum and E sambucinum formed macroconidia first, whereas E poae, E oxysporum and E verticillioides formed microconidia first. Different shape parameters of the spore images were calculated using a freely available software package (FRAGSTATS 3.3), which was originally designed for spatial pattern analysis of maps. Fusarium cerealis could neither be distinguished unambiguously from E sambucinum nor from E graminearum based on the spore shape parameters analysed here. All other species could be distinguished from each other based on significant differences of at least one of the calculated spore shape parameters.