The Stomatal Openings Occurred from Blue Light Photoreceptors Mediated Signal Transduction Pathway May be Enhanced by a Blue Light Stimulated Photosynthesis

Stomata open by transporting of osmotic materials to the guard cell vacuole. In the mechanisms of stomatal opening, the transports of osmotic materials between the guard cell cytoplasm and vacuole have not been studied much. There are also important lacks of the understanding about important information regarding tonoplast transport proteins and channels. Tonoplast has many types of channels related to K+ transport, among which are inward-K+ channels/FV, outward-K+ channels/FV, outward-TPK/VK channels and TPC1/SV channels. The two H+ transport enzymes in tonoplast, H+-ATPase and H+-PPase, transport H+ from the cytoplasm to vacuole actively. They serve to create an ideal pH condition for the many metabolisms inside the cytoplasm. K+ is transported from the cytoplasm to the vacuole. However, none of the cytosolic K+ can enter the vacuole because vacuole is too full of positive charges. Therefore, in order to increase the osmotic pressure of the guard cell vacuole, it is necessary to transport solutes that could replace K+. Tonoplast contains sucrose-H+ antiports, an active transport protein that can transport sucrose to the vacuole. Although various solutes including K+ are required for stomatal openings, sucrose is suggested to be the most important substance that may increase the osmotic pressure of the vacuole. In addition, the stomatal openings induced by the blue light-photoreceptor mediated signal transduction pathway are highly likely to reflect the effect of blue light stimulated photosynthesis. This is because numerous results have been published that photosynthesis could be induced even when a single blue light is treated without red light.

Automated summary

Stomata open by transporting osmotic materials to the guard cell vacuole. Various channels related to K+ transport and H+ transport enzymes in tonoplast play an essential role in creating an ideal pH condition for metabolisms. Sucrose is suggested to be the most important substance to increase the osmotic pressure of the vacuole, and blue light-induced stomatal openings may reflect the effect of blue light stimulated photosynthesis.