Light and temperature convergence in the control of plant development

CASAL, JORGE J.

Perth

Simposio; ComBio 2013; 2013

The light environment provides major cues in the control of plant growth and development. Although light signals can be specifically manipulated under laboratory conditions to rule out confounding effects, the natural environment is more complex. Light signals can overlap with changes in temperature or occur under extreme temperatures that could distort the light signalling mechanisms. We have observed that while constant elevated warm temperatures tend to oppose light effects on the control of plant development, short periods of high temperatures (heat shocks) enhance the effect of light on seedling morphology during the transition from skotomorphogenesis to photomorphogenesis. This synergism involves heat shock effects on two major branches of the light signalling network, i.e. the COP1-HY5 pathway and the PRR7/PRR9-LHY/CCA1-PIF4/PIF5 pathway. Via the second pathway, heat shocks generate a circadian rhythm of sensitivity to light. However, the action of the COP1-HY5 does not obviously involve the circadian clock. In addition, heat shocks modify the subcellular distribution of the light receptor phytochrome B but this effect bears no obvious relation with the physiological output. These observations indicate that heat shocks impact on key components of the light signalling network; while some of these effects can be regarded as noise others (which are dominant) reinforce light signalling and contain informative value for plant development.