One goal of the work presented here was to produce insertional C. graminicola mutants through an ATMT approach for further investigation due to finding mutants, which are not able to infect maize and therefore show a loss of pathogenicity or an impairment of virulence. Besides the ATMT transformation an inoculation system for artificial membranes (e. g. PTFE) was developed. It proved to be suitable for comparison of the penetration capability of phytopathogenic fungi (Colletotrichum graminicola, Magnaporthe oryzae, Phakopsora pachyrhizi), building melanized and non-melanized appressoria, respectively. Fungi with non-melanized appressoria could breach the artificial membranes as well as the ones with melanized appressoria. This result was confirmed by a cell collapse approach, showing that, independent of melanization, a high osmotic pressure could be found.