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Unique and unifying themes in the mechanisms regulating the expression of the arabidopsis thaliana PR-1 and Solanum tuberosum PR-10a inducible defense genes

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Show simple item record Boyle, Patrick 2010-10-25T19:27:06Z 2010-10-25T19:27:06Z 2010-10-25
dc.description.abstract Arabidopsis is a model plant used to study disease resistance; Solanum tuberosum or potato is a crop species. Both plants possess inducible defense mechanisms that are deployed upon recognition of pathogen invasion. Transcriptional reprogramming is crucial to the activation of defense responses. The Pathogenesis-Related (PR) genes are activated in these defense programs. Expression of Arabidopsis PR-l and potato PR-10a serve as markers for the deployment of defense responses in these plants. PR-l expression indicates induction of systemic acquired resistance (SAR). Activation of SAR requires accumulation of salicylic acid (SA), in addition to the interaction of the non-expressor of pathogenesis-related genes I (NPRI), with the TGA transcription factors. The PR-10a is activated in response to pathogen invasion, wounding and elicitor treatment. PR-10a induction requires recruitment of the Whirly I (Whyl) activator to the promoter. This locus is also negatively regulated by the silencer element binding factor (SEBF). We established that both the PR-l and PR-10a are occupied by repressors under non-inducing conditions. TGA2 was found to be a constitutive resident and repressor of PR-l, which mediates repression by forming an oligomeric complex on the promoter. The DNA-binding activity of this oligomer required the TGA2 N-terminus (NT). Under resting conditions we determined that the PR-10a is bound by a repressosome containing SEBF and curiously the activator Pto interacting protein 4 (Pti4). In the context of this repressosome, SEBF is responsible for PR-10a binding, yet rWe also showed that PR-l and PR-10a are activated by different means. In PR-l activation the NPRI NT domain alleviates TGA2-mediated repression by interacting with the TGA2 NT. TGA2 remains at the PR-l but adopts a dimeric conformation and forms an enhanceosome with NPRl. In contrast, the PR-10a is activated by evicting the repressosome and recruiting Why! to the promoter. These results advance our understanding of the mechanisms regulating PR-l and PR-10a expression under resting and inducing conditions. This study also revealed that the means of regulation for related genes can differ greatly between model and crop s en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Arabidopsis -- Molecular aspects en_US
dc.subject Solanum -- Molecular aspects en_US
dc.title Unique and unifying themes in the mechanisms regulating the expression of the arabidopsis thaliana PR-1 and Solanum tuberosum PR-10a inducible defense genes en_US
dc.type Electronic Thesis or Dissertation en_US Ph.D. Biotechnology en_US Doctoral en_US
dc.contributor.department Centre for Biotechnology en_US Faculty of Mathematics and Science en_US

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