Calcium oscillations in guard cell adaptive responses to the environment

Abstract

Ca2??has been shown to be a ubiquitous intracellular second messenger in plant cells, raising the question of how specificity is controlled in Ca2?-based signalling systems in plants. There is considerable interest in the possibility that stimulus-induced oscillations in the cytosolic concentration of free Ca2??can encode information used to specify the outcome of the final response through the generation of stimulus-specific Ca2??signatures. Recent results provide good evidence that, at least in stomatal guard cells, signalling information is encoded in oscillations and transients in [Ca2?]cyt, enabling stomata to formulate the optimal stomatal aperture to balance CO2 uptake for photosynthesis and water loss through transpiration under a specific set of environmental conditions. These findings are discussed here, together with models for the encryption and decoding of the signalling information encoded in guard cell Ca2??signatures.