SPATIAL CHARACTERISTICS OF CALCIUM SIGNALING - THE CALCIUM WAVE AS A BASIC UNIT IN PLANT-CELL CALCIUM SIGNALING

Many signals that modify plant cell growth and development initiate ch anges in cytoplasmic Ca2+. The subsequent movement of Ca2+ in the cyto plasm is thought to take place via waves of free Ca2+. These waves may be initiated at defined regions of the cell and movement requires rel ease from a reticulated endoplasmic reticulum and the vacuole. The mec hanism of wave propagation is outlined, and the possible basis of repe titive wave formation, Ca2+ oscillations and capacitative Ca2+ signall ing is discussed. Evidence for the presence of Ca2+ waves in plant cel ls is outlined, and from studies on raphides it is suggested that the capabilities for capacitative Ca2+ signalling are also present. The pa per 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 d evelopment.