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An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta
The sessile nature of plants demands that they respond appropriately to changes in their environment (stresses) in order to survive. Critical to survival is the maintenance of water and ion homeostasis. The mechanisms by which plants achieve this are poorly understood. Traditionally plant stress res...
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| Format: | Thesis |
| Language: | English |
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Department of Molecular and Cell Biology
2020
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| _version_ | 1867613284570497024 |
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| access_status_str | Open Access |
| author | Donaldson, Lara Elizabeth |
| author2 | Denby, Katherine |
| author_browse | Denby, Katherine Donaldson, Lara Elizabeth |
| author_facet | Denby, Katherine Donaldson, Lara Elizabeth |
| author_sort | Donaldson, Lara Elizabeth |
| collection | Thesis |
| description | The sessile nature of plants demands that they respond appropriately to changes in their environment (stresses) in order to survive. Critical to survival is the maintenance of water and ion homeostasis. The mechanisms by which plants achieve this are poorly understood. Traditionally plant stress responses were thought to be communicated by five classical plant hormones - auxin, cytokine, gibberellic acid, absisic acid and ethylene. Nowadays a plethora of other molecules are known to fulfil this function including nitric oxide, salicylic acid, jasmonic acid, brassinosteroids and peptide hormones. Plant natriuretic peptides have been proposed to be peptide hormones involved in maintaining water and ion homeostasis in plants. Evidence for this has been provided by studies of plant responses to exogenous natriuretic peptide treatment, however a demonstration of their function in planta remains outstanding. This study was undertaken to gain insight into the mechanisms regulating water and ion homeostasis in Arabdopsis by examining second messenger responses to stresses that perturb water and ion homeostasis; characterization of an Arabidopsis thaliana plant natriuretic peptide (atpnp-a) mutant and transcriptome analysis of AtPNP-A, in order to establish whether AtPNP-A plays a role in maintaining water and ion homeostasis in planta. Results indicated that recombinant AtPNP-A induces second messenger responses reminiscent of the response to NaCl, suggesting that AtPNP-A may play a signalling role in response to disturbances in water and ion homeostasis. In support of this, characterization of an atpnp-a mutant revealed that AtPNP-A is likely to be involved in processes that require adjustments to water and ion homeostasis including cell expansion, stomatal opening and NaCl and osmotic stress responses, consistent with reported responses to natriuretic peptide treatment. Furthermore, the atpnp-a mutant revealed a role for AtPNP-A in the defence response. Evidence to support this came from the computational analysis of AtPNP-A expression which correlates with genes involved in the defence response. Additionally, the transcriptome response to recombinant AtPNP-A treatment further implicated the involvement of AtPNP-A in the defence response. Therefore AtPNP-A is hypothesized to play a role in growth, abiotic and biotic stress responses that enables the plant to mount an integrated response to the environment. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/30848 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:41.762Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Molecular and Cell Biology |
| publisherStr | Department of Molecular and Cell Biology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/30848 An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta Donaldson, Lara Elizabeth Denby, Katherine Gehring, Chris Ingle, Rob Molecular and Cell Biology The sessile nature of plants demands that they respond appropriately to changes in their environment (stresses) in order to survive. Critical to survival is the maintenance of water and ion homeostasis. The mechanisms by which plants achieve this are poorly understood. Traditionally plant stress responses were thought to be communicated by five classical plant hormones - auxin, cytokine, gibberellic acid, absisic acid and ethylene. Nowadays a plethora of other molecules are known to fulfil this function including nitric oxide, salicylic acid, jasmonic acid, brassinosteroids and peptide hormones. Plant natriuretic peptides have been proposed to be peptide hormones involved in maintaining water and ion homeostasis in plants. Evidence for this has been provided by studies of plant responses to exogenous natriuretic peptide treatment, however a demonstration of their function in planta remains outstanding. This study was undertaken to gain insight into the mechanisms regulating water and ion homeostasis in Arabdopsis by examining second messenger responses to stresses that perturb water and ion homeostasis; characterization of an Arabidopsis thaliana plant natriuretic peptide (atpnp-a) mutant and transcriptome analysis of AtPNP-A, in order to establish whether AtPNP-A plays a role in maintaining water and ion homeostasis in planta. Results indicated that recombinant AtPNP-A induces second messenger responses reminiscent of the response to NaCl, suggesting that AtPNP-A may play a signalling role in response to disturbances in water and ion homeostasis. In support of this, characterization of an atpnp-a mutant revealed that AtPNP-A is likely to be involved in processes that require adjustments to water and ion homeostasis including cell expansion, stomatal opening and NaCl and osmotic stress responses, consistent with reported responses to natriuretic peptide treatment. Furthermore, the atpnp-a mutant revealed a role for AtPNP-A in the defence response. Evidence to support this came from the computational analysis of AtPNP-A expression which correlates with genes involved in the defence response. Additionally, the transcriptome response to recombinant AtPNP-A treatment further implicated the involvement of AtPNP-A in the defence response. Therefore AtPNP-A is hypothesized to play a role in growth, abiotic and biotic stress responses that enables the plant to mount an integrated response to the environment. 2020-01-31T10:56:22Z 2020-01-31T10:56:22Z 2009 2020-01-31T10:55:43Z Master Thesis Masters http://hdl.handle.net/11427/30848 eng application/pdf Department of Molecular and Cell Biology Faculty of Science |
| spellingShingle | Molecular and Cell Biology Donaldson, Lara Elizabeth An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| thesis_degree_str | Master's |
| title | An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| title_full | An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| title_fullStr | An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| title_full_unstemmed | An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| title_short | An investigation of the role of Arabidopsis thaliana plant natriuretic peptide in planta |
| title_sort | investigation of the role of arabidopsis thaliana plant natriuretic peptide in planta |
| topic | Molecular and Cell Biology |
| url | http://hdl.handle.net/11427/30848 |
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