Spatial characteristics to calcium signalling; the calcium wave as a basic unit in plant cell calcium signalling

Abstract

Many signals that modify plant cell growth and development initiate changes in cytoplasmic Ca2+. The subsequent movement of Ca2+in the cytoplasm is thought to take place via waves of free Ca2+. These waves may be initiated at defined regions of the cell and movement requires release from a reticulated endoplasmic reticulum and the vacuole. The mechanism of wave propagation is outlined and the possible basis of repetitive reticulum wave formation, Ca2+oscillations and capacitative Ca2+signalling is discussed. Evidence for the presence of Ca2+waves in plant cells is outlined, and from studies on raphides it is suggested that the capabilities for capacitative Ca2+signalling are also present. The paper finishes with an outline of the possible interrelation between Ca2+waves and organelles and describes the intercellular movement of Ca2+waves and the relevance of such information communication to plant development.