Roles of plant CBL-CIPK systems in abiotic stress responses

Plants evolved from long-term adaptation to form regulatory mechanisms of perception, transduction, and response to stresses. The CBL-CIPK signaling system is a basic calcium sensor that plays an important role in sensing adverse environmental stimuli. CBLs can perceive and bind Ca2+ under adversity and then specifically interact with CIPKs. The activated CBL-CIPK complex phosphorylates downstream target proteins (such as ion channels and transporters), or regulates transcription factors and stress responsive genes. Important progress has been made in the study of CBL-CIPK signaling pathways in response to high salt, low N, low K, high Mg, and high pH. This review summarizes the structural features of CBL and CIPK families and the research progress of CBL-CIPK complexes under environmental stresses, and forecasts the important future direction in studies of the CBL-CIPK signaling system.