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Title: Early events in plant-pathogen interactions
Author: Hann, Dagmar R.
ISNI:       0000 0004 2671 3869
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2008
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Plants are in constant contact with a wide range of microbes. Although many of them are potential pathogens, disease is the exception. This is partly due to a very effective immune response mounted by the plant. This immune response consists of two layers, both of which are innate. The first layer perceives the microbe directly after invasion, through recognition of pathogenassociated molecular patterns (PAMPs) by membrane localized pattern recognition receptors (PRRs). Microbes have developed specialized secretion systems for the delivery of effector proteins into the host cytoplasm, some of which act as suppressors PAMP-triggered immunity. In a second layer of immunity, some of these effectors are recognized in a cultivar specific manner by plant resistance genes. The defence response associated with effector recognition is also called effector-triggered immunity and usually leads to a very strong defence response in the form of localized cell death. In addition, some effector proteins were shown to suppress effector-triggered immunity. During my thesis I worked on several aspects of PAMP-triggered immunity and effector mediated suppression. Firstly, I identified and characterized the putative flagellin receptor in N. benthamiana termed NbF/s2 (Hann, DR and Rathjen, JP, The Plant Journal, 2007). Secondly, I performed a reverse genetic screen based on virus-induced gene silencing (VIGS) of a protein kinase gene library, to identify components involved in flagellin-elicited active oxygen generation in: N. benthamiana. With this screen I identified several kinases involved in defence signaling. One of these candidates encodes NbSerk3/BAK1, which was shown elsewhere to interact with the f1agellin receptor AtFLS2 in Arabidopsis (Heese, A, Hann DR, et al. PNAS, 2007). Thirdly, I investigated effector-mediated suppression of host defence responses. I focused on the P. syringae pv tomato DC3000 effectors AvrPto and AvrPtoB, which suppress a wide range of defence responses induced by various elicitors (Hann, DR and Rathjen, JP, The Plant Journal, 2007). I screened a library of P. syringae pv tabaci 11528 effectors and identified several suppressors of PAMP-triggered immunity. Interestingly, the range and specificity of defence-response suppression varied amongst the effectors tested, suggesting different host targets for each effector.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available