Calcium signaling in coordinating plant development, circadian oscillations and environmental stress responses in plants

Calcium (Ca2+) is an intracellular second messenger involved in many signal transduction pathways in plants. The perception of environmental and internal cues leads to alterations in the cytosolic Ca2+ signatures which translate into changes in gene expression and cellular functions. Herein, we review the novel roles of Ca2+ signalling in coordinating plant stem cell niche homeostasis for root and shoot development. We also summarize the regulatory networks between Ca2+ signalling and other plant signalling pathways which commence into activation or repression of genes involved in regulating vegetative to reproductive phase transition and light-mediated plant growth responses. The possible functions of Ca2+ in the input pathway as a second messenger, external stimuli and the output of the clock regulating the rhythmicity of the plant circadian system are being reviewed. Additionally, we have also highlighted the new insights into the roles of Ca2+ signalling components in the perception and regulation of abiotic/ biotic stress responses in plants.