Blue light inhibits guard cell plasma membrane anion channels in a phototropin-dependent manner
Article first published online: 22 FEB 2007
The Plant Journal
Volume 50, Issue 1, pages 29–39, April 2007
How to Cite
Marten, H., Hedrich, R. and Roelfsema, M. R. G. (2007), Blue light inhibits guard cell plasma membrane anion channels in a phototropin-dependent manner. The Plant Journal, 50: 29–39. doi: 10.1111/j.1365-313X.2006.03026.x
- Issue published online: 22 FEB 2007
- Article first published online: 22 FEB 2007
- Received 15 September 2006; revised 13 November 2006; accepted 20 November 2006.
- guard cell;
- anion channel;
- blue light;
Guard cells respond to light through two independent signalling pathways. The first pathway is initiated by photosynthetically active radiation and has been associated with changes in the intercellular CO2 concentration, leading to inhibition of plasma membrane anion channels. The second response is blue-light-specific and so far has been restricted to the activation of plasma membrane H+-ATPases. In a search for interactions of both signalling pathways, guard cells of Vicia faba and Arabidopsis thaliana were studied in intact plants. Vicia faba guard cells recorded in CO2-free air responded to blue light with a transient outward plasma membrane current that had an average peak value of 17 pA. In line with previous reports, changes in the current–voltage relation of the plasma membrane indicate that this outward current is based on the activation of H+-ATPases. However, when V. faba guard cells were blue-light-stimulated in air with 700 μl l−1 CO2, the outward current increased to 56 pA. The increase in current was linked to inhibition of S-type anion channels. Blue light also inhibited plasma membrane anion channels in A. thaliana guard cells, but not in the phot1 phot2 double mutant. These results show that blue light inhibits plasma membrane anion channels through a pathway involving phototropins, in addition to the stimulation of guard cell plasma membrane H+-ATPases.