Ca2+ channels and Ca2+ signals involved in abiotic stress responses in plant cells: recent advances

Calcium (Ca²⁺) signals are essential transducers and regulators in many adaptive and developmental processes in plants. Protective responses of plants to a variety of environmental stress factors are mediated by transient changes of Ca²⁺ concentration in plant cells. Ca²⁺ ions are quickly transported by channel proteins present on the plasma membrane. During responses to external stimuli, various signal molecules are transported directly from extracellular to intracellular compartments via Ca²⁺ channel proteins. Three types of Ca²⁺ channels have been identified in plant cell membranes: voltage-dependent Ca²⁺-permeable channels (VDCCs), which is sorted to depolarization-activated Ca²⁺-permeable channels (DACCs) and hyperpolarization-activated Ca²⁺-permeable channels (HACCs), voltage-independent Ca²⁺-permeable channels (VICCs). They make functions in the abiotic stress such as TPCs, CNGCs, MS channels, annexins which distribute in the organelles, plasma membrane, mitochondria, cytosol, intracelluar membrane. This review summarizes recent advances in our knowledge of many types of Ca²⁺ channels and Ca²⁺ signals involved in abiotic stress resistance and responses in plant cells.