Regulation of turor pressure is indispensable to plant cells. In algal cells, turgor pressure is regulated by changing intracellular osmotic pressure via transport of inorganic ions between vacuole and external medium. The brackish water alga, Lamprothamnium succinctum regulate turgor pressure upon hypotonic treatment by releasing K+ and Cl-. We have found that an increase in cytoplasmic free Ca2+ concentration ([Ca2+]c) occurs upon hypotonic treatment. The signal of an increase in turgor pressure may be transduced into this signal, an increase in [Ca2+]c', which would control channel-mediated ion transport from vacuole to extenal medium.
