Outbreaks of a lethal type of Verticillium wilt of hops (Humulus lupulus L.) are reported yearly. This disease is caused by a phytopathogenic fungus Verticillium nonalfalfae (Vna) and presents in wilting, chlorosis, necrosis, and plant death. In order to successfully colonize its host, Vna secrets effector proteins, which protect the fungus and modulate the plant immune system or plant physiology. Understanding the function of candidate secreted effector proteins (CSEPs) and knowledge of host interacting molecules is a crucial contribution to development of effective strategies for pest control and can accelerate breeding of Vna resistant cultivars. In the presented doctoral thesis, we characterized candidate effector proteins VnaChtBP and VnaSSP4.2, which were selected based on previous studies. Using confocal microscopy, a nucleo-cytosolic subcellular localization was determined for both effectors expressed in model plant Nicotiana benthamiana. Infiltration of recombinant proteins to various plants did not confirm the hypothesis of VnaChtBP or VnaSSP4.2 involvement in PTI or ETI responses. We were able to show that the recombinant protein VnaSSP4.2 binds to PIP, cadiolipin and sulfatide molecules, all known modulators of plant immunity. We determined that the effector VnaChtBP binds specifically to chitin and protects the fungus from degradation by plant chitinases.
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