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Characterization of the roles of turnip crinkle virus coat protein and the NAC transcription factor tip in eliciting resistance and hypersensitive responses in Arabidopsis thaliana
The Arabidopsis - Turnip crinkle virus (TCV) model system has proved very useful in studying the molecular aspects of defense mechanisms mediated by virus - host interactions. It has been established that, in addition to its structural role, TCV coat protein (CP) has multiple roles in virus - host interactions both as a silencing suppressor as well as a modulator of the host anti-viral resistance responses. Previous studies from our laboratory demonstrated that CP binds to an Arabidopsis protein TIP, a member of the NAC transcription factors. Analysis of infections by a series of mutant viruses with single amino acid substitutions near the N-terminus of the CP implicated TIP binding ability of the CP with modulation of the host resistance response in both susceptible (Col-0) and resistant (Di-17) ecotypes of Arabidopsis. My research focused on understanding the roles of CP and TIP in eliciting the plant resistance. I mapped the region of the CP responsible for induction of the HR to the R domain. I confirmed that R domain alone in the presence of HRT, but in the absence of TIP, was sufficient for HR induction. I also identified a putative nuclear localization signal (NLS) which also resides in N-terminus of TCV CP. In studies using GPF-CP, I demonstrated that the ability of TCV CP to migrate into the nucleus and form inclusion-like structures near Cajal bodies was closely related to the ability of TCV CP to induce HR. This was confirmed by demonstrating that addition of a nuclear exclusion signal to CP eliminated its ability to initiate an HR. In the final chapter, I examined the role of TIP in modulating HR and demonstrated that presence of TIP delayed the onset of HR possibly by directly sequestering the CP at the periphery of the nucleus. Together, my studies permitted the formulation of a refined model for the involvement of both CP and TIP in both the basal and ETI resistance responses to TCV infection.
Plant biology|Plant Pathology|Virology
Kang, Sung Hwan, "Characterization of the roles of turnip crinkle virus coat protein and the NAC transcription factor tip in eliciting resistance and hypersensitive responses in Arabidopsis thaliana" (2012). ETD collection for University of Nebraska - Lincoln. AAI3525707.