Analysis of phytochrome null mutants has revealed roles for these photoreceptors throughout plant development, synchronising developmental events to daily and seasonal environmental changes. The roles of the phytochromes in shoot photomorphogenesis is relatively well characterised, but little is known about their influence on root development. Over the course of my PhD I have shown that phytochromes are in fact important regulators of root phenotype. My results demonstrate that application of low R:FR ration light, which reduces the active phytochrome pool (Pfr), changes the distribution of expression of the synthetic auxin reporter gene <i>DR5::</i>GUS, which in turn correlates with a reduction in lateral root emergence. Thus, I have identified a long distance signalling role for shoot phytochromes, acting collectively to control the emergence of lateral roots, at least partly by manipulating the early shoot-root auxin pulse. I have shown that phytochromes are present and light regulated in roots, and propose that phytochromes are able to act locally to regulate root hair elongation. My analysis of the interaction between <i>phyB</i> and <i>shy2-2</i> implicates these genes in the regulation of microtubule stability, and consequently of cytoskeleton organisation. I have also provided evidence that the Pr form of phytochrome, previously thought to be physiologically inactive, does in fact have important roles in the regulation of root development. I have taken a novel approach to understanding phytochrome signalling, and have opened many new lines of enquiry into an exciting new area of photobiology.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:661535 |
| Date | January 2006 |
| Creators | Salisbury, Frances J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11352 |
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