Calcium-permeable channels in plant cells

Calcium signal transduction is a central mechanism by which plants sense and respond to endogenous and environmental stimuli. Cytosolic Ca2+ elevation is achieved via two cellular pathways, Ca2+ influx through Ca2+ channels in the plasma membrane and Ca2+ release from intracellular Ca2+ stores. Because of the significance of Ca2+ channels in cellular signaling, interaction with the environment and developmental processes in plants, a great deal of effort has been invested in recent years with regard to these important membrane proteins. Because of limited space, in this review we focus on recent findings giving insight into both the molecular identity and physiological function of channels that have been suggested to be responsible for the elevation in cytosolic Ca2+ level, including cyclic nucleotide gated channels, glutamate receptor homologs, two-pore channels and mechanosensitive Ca2+-permeable channels. We provide an overview of the regulation of these Ca2+ channels and their physiological roles and discuss remaining questions.