Candida glabrata (C. glabrata) was first described as a commensal of the human gut flora. However, soon afterwards it was shown to cause invasive fungal infections in the immunocompromised host. While most invasive Candida infections are still caused by Candida albicans (C. albicans), the incidence of invasive Candida infections by non-albicans strains has been on the rise. About 20 - 30 % of these infections are nowadays caused by C. glabrata. One cause for this shift is likely the widespread use of azole-based antifungals in prophylaxis. Furthermore, there have been several reports of echinocandin-resistant C. glabrata strains due to mutations in cell wall-related genes. At the same time, the virulence factors of C. glabrata remain enigmatic. In order to elucidate the underlying mechanism of C. glabrata virulence and drug resistance, a genome-scale collection of gene deletion mutants was published by Schwarzmüller et al. in 2014. The first aim of this thesis was to expand this collection of gene deletion mutants. To do so, more than 90 new gene deletion mutants were constructed. In addition, the combined C. glabrata deletion mutant collection of published and new strains was subjected to a novel liquid screening method. This approach was developed during this thesis and offers a higher sensitivity compared to a solid media screening. At the same time it significantly decreases the amount of screening drugs required. This allowed not only to verify the published results but to identify more than 80 new phenotypes. Importantly, about 20 of these new phenotypes concern antifungal drug resistance against echinocandins and azoles. In addition, all the results were verified by an adapted version of the EUCAST protocol. The second aim of this thesis was to elucidate the role of the Ypk1 kinase in C. glabrata. This thesis shows that Ypk1 is part of a network of kinases implied in the antifungal tolerance of C. glabrata. Importantly, this has been verified in clinical isolates. Furthermore, this thesis presents evidence that the newly identified network is connected to two known signaling pathways including the MAP kinases Slt2 and Kss1. Interestingly, the deletion of YPK1 causes changes and stress responses similar to caspofungin treatment in C. glabrata. Lastly, RNA sequencing identified several putative downstream targets of this new Ypk-mediated network. In summary, this thesis expands the knowledge on the mechanisms underlying C. glabrata drug resistance and virulence. At the same time, it establishes several tools that will greatly help future research on C. glabrata. This is also supported by the number of publications and side projects that involved strains and methods from this thesis.