XVI International Botanical Congess

The observation that an elevation in cytosolic free Ca is a component in signal transduction pathways leading to both increases and decreases in guard cell turgor prompts the question of how specificity is encoded in Ca based signalling systems. One mechanism that might contribute to the control of specificity is the calcium signature" - or stimulus specific increases in intracellular Ca. The ability to generate Ca signatures might be dependent on the ability of a signal to access multiple Ca release pathways. Using the response of guard cells to abscisic acid as an example, data will be presented showing that ABA is able to generate increases in Ca by accessing plasma membrane Ca influx channels, a phospholipase C based signalling pathway and through the use of cADP ribose as a Ca mobilising second messenger.