Changes in cytosolic free Ca2 concentrations ([Ca2]c)

are essential for the transduction of various abiotic and biotic signals in plants (Sanders et al. 2002). Ca2 is thought to be mobilized into the cytosol by influx from outside the cell or from intracellular Ca2 stores, such as the vacuole and endoplasmic reticulum, via Ca2 channels. However, the molecular bases for these dynamics are only just becoming apparent. In recent years, candidates for the Ca2 channel-encoding gene family, TPCs (two-pore channels) hav