Investigation of proteins at the apple scab interface

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dc.contributor.advisor Plummer, Kim en
dc.contributor.advisor Greenwood, Dave en Fitzgerald, Anna en 2007-08-06T06:37:03Z en 2007-08-06T06:37:03Z en 2004 en
dc.identifier THESIS 05-046 en
dc.identifier.citation Thesis (PhD--Biological Sciences)--University of Auckland, 2004 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Venturia inaequalis is the fungal phytopathogen that causes apple scab. In this thesis a reverse genetics approach to identify pathogenicity proteins of V. inaequalis is reported. A 'directed proteomics' approach was employed to analyse proteins isolated from the site of the V. inaequalis-apple interaction. Two proteins secreted by V. inaequalis, during its biotrophic infection of apple seedling leaves, were identified. One has similarity to the Alt A allergen protein of Alternaria alternata and the other to a yeast β-glucosidase. V. inaequalis β-glucosidases are capable of releasing the plant growth regulator cytokinin from its glycoside residue. Cytokinin has been implicated in nutrient acquisition in biotrophic fungi. The in planta function of the Alt A allergen in A. alternate is unknown, although a related protein in A. brassicicola is up-regulated during spore germination. In planta expression studies indicated a possible role for the V. inaequalis proteins in the development of infection. The fungal proteins identified during this study were also previously identified in an investigation into avirulence proteins secreted by V. inaequalis. In addition, several plant proteins that may be involved in the plant-pathogen interaction were also detected. A system for RNA-mediated gene silencing in V. inaequalis was developed for future functional analysis of the fungal proteins. Hairpin constructs were transferred to V. inaequalis by Agrobacterium tumefaciens to achieve high frequency, simultaneous silencing of an endogenous, melanin biosynthesis, gene (trihydroxynaphthalene reductase) and a transgene (GFP), which produced obvious phenotypes in vitro. In simultaneous silencing experiments, when one gene was silenced, expression of the other gene was also reduced to a similar extent. Significant reductions in expression of the melanin biosynthesis gene did not appear to effect pathogenicity of the fungus. The ability to silence two genes at once, when one is an indicator of silencing, extends the technique for use with genes expressed exclusively during infection. A complete system is now in place for the identification and characterisation of V. inaequalis proteins involved in pathogenicity. en
dc.language.iso en en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99146935514002091 en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights.uri en
dc.title Investigation of proteins at the apple scab interface en
dc.type Thesis en Biological Sciences en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en

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