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. <i>A. thaliana</i> 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 <i>A. thaliana</i> 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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:641719 |
| Date | January 2006 |
| Creators | Bleakley, Claire |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14128 |
Page generated in 0.0022 seconds