Interaction of light and temperature on the phytochrome: PIF signalling complex
Date
29/06/2013Author
Hemsted, Joseph Rustat
Metadata
Abstract
Light and temperature are two of the most important non-biological signals that plants
must be able to sense and respond to. However, it is not just the individual signals, but
the interaction between them that is important. In the dark, Arabidopsis has strongly
reduced temperature plasticity. The red light photoreceptor phyB and the PIF family of
transcription factors have previously been identified as key regulators of this response.
Computer modelling was used to study the interaction between the proteins, to explain
counter-intuitive behaviour at certain light conditions. A fluence rate dependent response
to temperature was uncovered, where high temperature causes a reversal of the
normal seedling response to light. In a PIF and phyB dependent manner, increasing
light intensity in the warm can lead to an increase in hypocotyl elongation, the opposite
of what has been previously published. This was shown to be dependent on an apically
derived response to high fluence rates, independent of the Phytochromes. To extend
the analysis beyond the seedling stage, the adult phenotypes of light signalling mutants
were subsequently characterised at different temperatures. The temperature dependent
control of flowering time and leaf growth were both dependent on Phytochrome and the
PIFs, but in apparent opposite directions. This demonstrates that the light signalling
system in plants is a complex network of signalling factors, affecting each other in a
dynamic process to respond to light and temperature.