Calcium signaling in plants: Universal and unique paradigms

Rooted in place, plants must continuously respond and adapt to their ever-changing environment to survive, especially as climate change intensifies. Calcium ions (Ca²⁺) play a central role in plant responses to both biotic and abiotic challenges. Ca²⁺ signaling involves the coordinated action of channels and transporters that generate specific "Ca²⁺ codes," along with Ca²⁺-binding proteins that act as sensors to decode them. Studies over the past several decades have explored the molecular components that form the toolkit, pathways, and networks for the coding and decoding of Ca²⁺ signals in plants. This review focuses on the emerging mechanisms of calcium signaling in plants, beginning with an overview of the universal conceptual framework that governs the coding and decoding of Ca²⁺ signals, followed by examples of pathways in plant growth and reproduction, responses to abiotic stress and microbes, and systemic signaling in plants.