Since the late 90s, maize farmers in South Africa have been plagued by grey leaf spot disease (GLS) caused by the fungal pathogen Cercospora zeina. The development of tan colored, matchstick-like lesions on infected leaves reduces their ability to capture radiant energy and convert it into products needed for grain filling and kernel development, ultimately reducing the quality and quantity of maize harvests.  Despite being one of the most prevalent diseases of maize in South Africa, the molecular mechanisms underlying this disease remain unknown. Using a combination of host-pathogen transcriptomic profiling, Agrobacterium-mediated transient transformation assays and protein structural phylogenetics, my PhD study aims to investigate the infection biology of C. zeina at the molecular level to gain insights into how it causes disease on maize. This information can be used as a foundation for future research as well as to bolster current resistance breeding strategies and help identify targets for the development of RNA interference-based bio-fungicides.