Calcium-Dependent Protein Kinases in Plants: Structure, Signaling, and Multifaceted Regulatory Roles in Development and Stress Adaptation

Calcium-dependent protein kinases (CDPKs) are crucial calcium sensors in plants that perceive transient calcium fluctuations. Structurally, CDPKs contain an integrated serine/threonine protein kinase domain, which enables them to function as protein kinases. Through phosphorylation of downstream target proteins, CDPKs transduce specific calcium-encoded signals to regulate diverse physiological processes. As pivotal signaling molecules, CDPKs function as critical regulators in plant growth, development, and stress responses. This review comprehensively summarizes the structure of CDPKs and their signal transduction mechanisms. It further elaborates on the multifaceted functions of CDPKs across diverse plant species, encompassing their regulatory roles in developmental processes, responses to abiotic and biotic stresses, and intricate interactions with phytohormone signaling pathways.