Abstract
Stomata open by blue light. The opening is induced by the plasma membrane H+-ATPase. Phototropins (phot1, phot2) function as blue light receptors, which lead to the H+-ATPase activation. In this talk, we will show our recent progresses on the signaling between phototropins and the H+-ATPase in guard cells. We obtained evidence that the type 1 protein phosphatase mediated the signaling between phototropins and the H+-ATPase. Phototropins undergo autophosphorylation by blue light, however, physiological role of the autophosphorylation has been unknown. We found that the phosphorylation sites in the kinase domain had the essential role for stomatal opening. We also found that the autophosphorylation was required for other responses, including phototropism, chloroplast accumulation, and leaf flattening. We have found that the fern Adiantum does not have blue light specific stomatal opening, and will show that the stomatal opening in the fern is mediated by guard cell chloroplasts.
