XVI International Botanical Congess

Ca2 is a key intracellular messenger that signals responses to numerous stimuli, in plants. We have been investigating the role of Ca2 in the perception of anoxia by maize seedlings and cells. Our past work showed that cytosolic Ca2 rapidly rises in response to O2 deprivation and may trigger gene activation and tolerance to anoxia. Recently, we have shown that the anoxic Ca2+ signal may originate from mitochondria. In this presentation, recent data on two new components in this signaling pathway will be discussed. The first of these is a novel calmodulin-binding Ca2 ATPase, whose activity could be important in regulating Ca2+ -dependent cysteine protease associated with the root tip death under anoxia. Our results suggest an adaptive role for this enzyme in submerged maize seedlings.