Novel genes regulating susceptibility to Fusarium oxysporum in Arabidopsis thaliana

Brendan Kidd (2011). Novel genes regulating susceptibility to Fusarium oxysporum in Arabidopsis thaliana PhD Thesis, School of Agriculture and Food Sciences, The University of Queensland.

       
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Author Brendan Kidd
Thesis Title Novel genes regulating susceptibility to Fusarium oxysporum in Arabidopsis thaliana
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
Publication date 2011-01
Thesis type PhD Thesis
Total pages 168
Total colour pages 25
Total black and white pages 143
Subjects 06 Biological Sciences
Abstract/Summary The soil-borne fungal pathogen, Fusarium oxysporum, causes wilt disease in over 120 different plant species. Spores of F. oxysporum have been known to persist in the soil for up to a decade and therefore developing resistant cultivars is the only effective long term solution to combat this pathogen. To understand the genetic basis of plant resistance, this PhD project has been using the model plant Arabidopsis thaliana to identify novel genes that provide resistance and susceptibility to F. oxysporum. In particular this project has focused on characterising the role of the PHYTOCHROME AND FLOWERING TIME1 (PFT1) gene in regulating F. oxysporum resistance. PFT1 encodes a subunit (MED25) of the multi-protein complex called Mediator. The Mediator complex has an essential role in co-ordinating gene expression and the research presented in this thesis has shown that the PFT1 gene is required for uncompromised expression of plant defense genes as well as resistance and susceptibility to different fungal plant pathogens. The pft1 mutant shows a broad reduction in a range of jasmonate-associated gene expression and the role of PFT1 in modulating the jasmonate pathway is discussed. In addition, the transcriptional response of wild type Arabidopsis leaves to a F. oxysporum root infection using the Affymetrix ATH1 array was investigated. In these analyses, an increase in jasmonate biosynthesis and signaling genes as well as an increase in the tryptophan biosynthetic pathway and its downstream components, such as the auxin and glucosinolate biosynthesis pathway, were found. Mutational analyses of these pathways showed that genes involved in auxin signaling and transport provide susceptibility to F. oxysporum. In contrast, auxin biosynthesis and glucosinolate biosynthesis genes, which were induced by F. oxysporum, had no effect on resistance. Overall this project has investigated factors required for resistance and susceptibility to F. oxysporum. The analysis of global expression changes that occurred within the leaves during F. oxysporum infection identified genes that are essential for full development of the disease response in the above ground tissue. In addition, the exploration of PFT1 and other subunits of the Mediator complex has revealed a previously unidentified layer of plant defense regulation and added a new component to the jasmonate signaling pathway. Identification of regulatory genes such as PFT1 could provide novel opportunities for improving disease resistance in crop plants.
Keyword PFT1
Mediator
Fusarium oxysporum
Jasmonate
Auxin
Defense
Gene Expression
Arabidopsis thaliana
Transcription Factor
Susceptibility
Additional Notes colour pages 22,24,29-32,34,35,37,38,48,50,53,56,115-121,127,137-139

 
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Created: Wed, 22 Jun 2011, 11:44:09 EST by Mr Brendan Kidd on behalf of Library - Information Access Service