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Title: Dissection of nitrate signalling in Arabidopsis thaliana
Author: Bleakley, Claire
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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Abundance of nitrite in the soil is very variable requiring plants to evolve adaptive growth responses in order the optimise uptake. Nitrate is known to induce its own uptake and assimilation and many nitrate responsive genes have been identified. However, how nitrate is sensed is not known. A genetic screen was designed to identify components of early nitrate signalling and perception. A. thaliana luciferase reporter lines of nitrite reductase NiR, and an ammonium transporter AMT1.1 were characterised and found not suitable for use in a genetic screen. A new transgenic luciferase reporter line driven by the high affinity nitrate transporter NRT2.1 was generated and characterised and found to be suitable for use in a genetic screen. Split root experiments with the NRT2.1 reporter lines showed that this gene responds to local signalling. Pharmacological analysis using A. thaliana cell suspension cultures to identify signalling mechanisms involved in early nitrate signalling revealed a novel sucrose-dependent cyclohexamide effect, where CHX exerts no effect on nitrate gene induction of NiR and NRT2.1 when sucrose levels are high but when sucrose levels are low CHX treatment results in a reduction in the nitrite gene induction response. This may indicate a putative role for new protein synthesis in the nitrate gene induction response when sucrose is limiting. Investigation of the nitrite transport analog, cholate, showed that this molecule is not also a signalling analog as it failed to induce the nitrate responsive genes, NiR and NRT2.1.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available