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

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