Specificity and integration of responses: Ca2+ as a signal in polarity andosmotic regulation

Plants can respond to changes in their external environment by making physi ological adaptations and by altering their growth patterns. These adaptatio ns are made against an overall developmental pattern which remains essentia lly unchanged during morphogenesis. It is becoming clear that several stimu lus-response coupling pathways share the same or similar components to thos e involved in initiating and maintaining developmental patterns. This revie w discusses some specific examples which provide insights into how Ca2+ can be used as a second messenger to bring about different physiological and d evelopmental responses in the same cells.