Detection of candidate secreted effector proteins (CSEPs) function is key to understanding the interaction between phytopathogenic organisms and plant hosts. The hemibiotrophic phytopathogenic vascular wilt fungus Verticillium nonalfalfae, which primarily infects hops (Humulus lupulus L.), produces four known apoplastic effector proteins VnaPRX1.1277 (class II peroxidase), VnaSSP4.2, VnaUn.279 and VnaChtBP (chitin binding protein), however, it has no known cytoplasmic effector proteins. The aim of the master's thesis was to characterize the candidate secretory effector protein Vna7.443, selected on the basis of previous studies. Homologous proteins, potential target cell processes, and basic descriptive parameters were determined for the Vna7.443 protein by bioinformatics approaches. Subcellular localization of Vna7.443 fusion proteins with mRFP labeling at the C- and N-terminal end was performed by confocal microscopy on Agrobacterium tumefaciens-transformed Nicotiana benthamiana leaf sections. The results showed that Vna7.443 protein is likely a cytoplasmic effector protein that, when the C-terminal end is free, localizes to the plant cell nucleus, but does not trigger a hypersensitive response in planta. Vna7.443 contains eight tandem WD40 repeats and has preserved homologues within fungal genuses Verticillium, Cercospora and Fusarium.
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