Evolution of an extracellular pathogen recognition mechanism in Solanaceae
<p>The innate immune system of plants depends on resistance (<em>R</em>) genes which provide durable resistance to pathogens in nature. Although many <em>R</em> genes have been identified, the molecular mechanism by which they function is only understood for a few.</...
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| Format: | Thesis |
| Language: | English |
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2018
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| _version_ | 1824459328997818368 |
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| author | Kourelis, J |
| author_facet | Kourelis, J |
| author_sort | Kourelis, J |
| collection | OXFORD |
| description | <p>The innate immune system of plants depends on resistance (<em>R</em>) genes which provide durable resistance to pathogens in nature. Although many <em>R</em> genes have been identified, the molecular mechanism by which they function is only understood for a few.</p>
<p>To study these mechanisms, I present four papers on the molecular mechanisms by which <em>R</em> gene products function, and one paper on a resource useful for the plant-pathogen community. First, I present a review and meta-analysis of the molecular mechanisms by which <em>R</em> gene products function, thereby identifying nine molecular mechanisms conferring pathogen resistance in plants. Second, I describe the evolutionary processes which have given rise to an indirect apoplastic recognition mechanism in the nightshade (Solanaceae) family. Tomato varieties carrying <em>Cf-2</em>, which encodes for a receptor-like protein, recognize the fungal-derived small secreted protein Avr2. This recognition requires the tomato gene <em>Rcr3</em>, which encodes for a papain-like cysteine protease. I show that <em>Cf-2</em> has likely evolved very recently, implicating that molecular recognition is a novel molecular function of the pre-existing <em>Rcr3</em>. I discuss this in a broader evolutionary context of similar recognition mechanisms. Third, I comment on a paper in which a similar resistance mechanism was engineered to alter its recognition spectrum. Fourth, I identify the amino acid residues in Rcr3 required for <em>Cf-2</em>-dependent recognition of Avr2 and I engineer another protease to replace Rcr3 for the recognition of Avr2. This potentially enables future engineering of this molecular mechanism for an altered recognition spectrum. Finally, using the proteome derived from re-annotated gene models of the plant model organism <em>Nicotiana benthamiana</em>, I show that the apoplast is enriched for enzymes with hydrolytic functions.</p>
<p>By elucidating the evolution of a pathogen recognition mechanism in Solanaceae and establishing the engineering of this mechanism, this thesis provides a framework for the generation of an altered recognition spectrum not found in nature.</p> |
| first_indexed | 2025-02-19T04:40:03Z |
| format | Thesis |
| id | oxford-uuid:c13386e8-0fb2-4ec5-9390-333764c8ee13 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2025-02-19T04:40:03Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | oxford-uuid:c13386e8-0fb2-4ec5-9390-333764c8ee132025-02-17T08:12:01ZEvolution of an extracellular pathogen recognition mechanism in SolanaceaeThesishttp://purl.org/coar/resource_type/c_db06uuid:c13386e8-0fb2-4ec5-9390-333764c8ee13Plant ScienceEnglishHyrax Deposit2018Kourelis, J<p>The innate immune system of plants depends on resistance (<em>R</em>) genes which provide durable resistance to pathogens in nature. Although many <em>R</em> genes have been identified, the molecular mechanism by which they function is only understood for a few.</p> <p>To study these mechanisms, I present four papers on the molecular mechanisms by which <em>R</em> gene products function, and one paper on a resource useful for the plant-pathogen community. First, I present a review and meta-analysis of the molecular mechanisms by which <em>R</em> gene products function, thereby identifying nine molecular mechanisms conferring pathogen resistance in plants. Second, I describe the evolutionary processes which have given rise to an indirect apoplastic recognition mechanism in the nightshade (Solanaceae) family. Tomato varieties carrying <em>Cf-2</em>, which encodes for a receptor-like protein, recognize the fungal-derived small secreted protein Avr2. This recognition requires the tomato gene <em>Rcr3</em>, which encodes for a papain-like cysteine protease. I show that <em>Cf-2</em> has likely evolved very recently, implicating that molecular recognition is a novel molecular function of the pre-existing <em>Rcr3</em>. I discuss this in a broader evolutionary context of similar recognition mechanisms. Third, I comment on a paper in which a similar resistance mechanism was engineered to alter its recognition spectrum. Fourth, I identify the amino acid residues in Rcr3 required for <em>Cf-2</em>-dependent recognition of Avr2 and I engineer another protease to replace Rcr3 for the recognition of Avr2. This potentially enables future engineering of this molecular mechanism for an altered recognition spectrum. Finally, using the proteome derived from re-annotated gene models of the plant model organism <em>Nicotiana benthamiana</em>, I show that the apoplast is enriched for enzymes with hydrolytic functions.</p> <p>By elucidating the evolution of a pathogen recognition mechanism in Solanaceae and establishing the engineering of this mechanism, this thesis provides a framework for the generation of an altered recognition spectrum not found in nature.</p> |
| spellingShingle | Plant Science Kourelis, J Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title | Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title_full | Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title_fullStr | Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title_full_unstemmed | Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title_short | Evolution of an extracellular pathogen recognition mechanism in Solanaceae |
| title_sort | evolution of an extracellular pathogen recognition mechanism in solanaceae |
| topic | Plant Science |
| work_keys_str_mv | AT kourelisj evolutionofanextracellularpathogenrecognitionmechanisminsolanaceae |