Zymoseptoria tritici is the causal agent of septoria tritici blotch (STB), which is a devastating foliar wheat disease worldwide. The research presented in this PhD thesis aims at understanding the biological functions of (a)virulence factors playing an essential role in the infection process of wheat by Z. tritici. Initially, We generated 22 entry constructs that form a new molecular toolbox based on gateway technology facilitating the rapid construction of binary vectors for fungal transformations. Additionally, we build up a list of promising effector genes that remain to be further explored in future studies. Eventually, we functionality analyzed several pathogenicity factors enabling this fungus to successfully colonize and infect its host.