P-type calcium ATPases play important roles in biotic and abiotic stress signaling.

Main conclusion: Knowledge of Ca²⁺-ATPases is imperative for improving crop quality/ food security, highly threatened due to global warming. Ca²⁺-ATPases modulates calcium, essential for stress signaling and modulating growth, development, and immune activities. Calcium is considered a versatile secondary messenger and essential for short- and long-term responses to biotic and abiotic stresses in plants. Coordinated transport activities from both calcium influx and efflux channels are required to generate cellular calcium signals. Various extracellular stimuli cause an induction in cytosolic calcium levels. To cope with such stresses, it is important to maintain intracellular Ca²⁺ levels. Plants need to evolve efficient efflux mechanisms to maintain Ca²⁺ ion homeostasis. Plant Ca²⁺-ATPases are members of the P-type ATPase superfamily and localized in the plasma membrane and endoplasmic reticulum (ER). They are required for various cellular processes, including plant growth, development, calcium signaling, and even retorts to environmental stress. These ATPases play an essential role in Ca²⁺ homeostasis and are actively involved in Ca²⁺ transport. Plant Ca²⁺-ATPases are categorized into two major classes: type IIA and type IIB. Although these two classes of ATPases share similarities in protein sequence, they differ in their structure, cellular localization, and sensitivity to inhibitors. Due to the emerging role of Ca²⁺-ATPase in abiotic and biotic plant stress, members of this family may help promote agricultural improvement under stress conditions. This review provides a comprehensive overview of P-type Ca²⁺-ATPase, and their role in Ca²⁺ transport, stress signaling, and cellular homeostasis focusing on their classification, evolution, ion specificities, and catalytic mechanisms. It also describes the main aspects of the role of Ca²⁺-ATPase in transducing signals during plant biotic and abiotic stress responses and its role in plant development and physiology.