Abstract
Stomata open in response to blue light (BL). Recent progresses of BL signaling in stomatal guard cells will be presented. BL activates the plasma membrane H+-ATPase and induces H+ pumping, which provides driving force for the uptake of K+. The H+-ATPase was activated by phosphorylation of penultimate Thr in the C-terminus with concomitant binding of 14-3-3 protein. The activation required the binding of 14-3-3 protein to the C-terminus. Involvement of phototropin (phot) in the perception of BL in guard cells was demonstrated using the phot1 phot2 double mutant. In the mutant, stomata neither open nor pump out H+ from guard cells in response to BL. When the double mutant was transformed with wild-type phot1, BL-induced stomatal opening was restored. Biochemical analysis indicated that phot was involved in the perception of BL. phot was phosphorylated in response to BL, and the phosphorylation preceded the activation of the plasma membrane H+-ATPase.
