Thesis
Molecular interactions between wheat and Pseudomonas fluorescens: role of DAPG and type III secretion on early changes in root gene expression
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/102958
Abstract
The antifungal metabolite 2,4-diacetylphloroglucinol (DAPG) is produced by certain fluorescent Pseudomonas spp. and is capable of functioning as a microbe associated molecular pattern (MAMP) or factor that triggers the plant immune response to foliar pathogens. In Triticum aestivum L. (wheat), the root-colonizing bacterium Pseudomonas fluorescens strain Q8r1-96 modulates multiple stress pathways in wheat roots and is known to play a role in biological control. Strain Q8r1-96 is a DAPG producer that colonizes wheat roots rapidly and maintains its populations on roots over a sustained period. Much is known about the role of DAPG in induced systemic resistance (ISR) (foliar response) but not much is known about localized root responses at the molecular level. To study the molecular mechanisms underlying this triggered immunity in wheat roots, two wheat cultivars, Buchanan and Tara, were selected because they differentially support rhizoplane DAPG accumulation. In Chapter 1, I tested the hypothesis that DAPG is important for localized root defense responses, therefore, a DAPG mutant of Q8r1-96 should differ from the wild type in induction of root gene expression. The functional type III secretion system (T3SS) of Q8r1-96 was shown to inhibit PAMP triggered immunity (PTI) responses on tobacco leaves; however, the responses of wheat root genes remain unknown. In Chapter 2, I tested the hypothesis that localized roots defense responses are governed by bacterial effectors introduced into the host by the T3SS. The results showed that DAPG and T3SS are not key factors for inducing targeted defense/stress responses in wheat roots. Moreover, our findings revealed a cultivar-dependent response to all three strains of bacteria including Q8r1-96, 4C5, and PST.
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Details
- Title
- Molecular interactions between wheat and Pseudomonas fluorescens
- Creators
- Chan Maketon
- Contributors
- Patricia Okubara (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525055401842
- Language
- English
- Resource Type
- Thesis