Decoding Calcium Signaling: Functional Roles of Calmodulin and Calmodulin‑Like Proteins in Plant Development and Stress Responses.

Calcium (Ca2+) acts as a ubiquitous secondary messenger in plants, orchestrating adaptive responses to developmental cues and environmental fluctuations. The decoding of these signatures is primarily mediated by calmodulin (CaM) and plant-specific calmodulin-like (CML) protein family. While canonical CaMs are evolutionarily conserved and feature high-affinity-binding motifs, CMLs exhibit substantial sequence divergence and structural variability, enabling functional specialization. This review synthesizes current knowledge on the structural characteristics and functional roles of CaMs and CMLs, emphasizing their pivotal contributions to plant development, stress resilience, and secondary metabolism. We highlight the significance of spatial compartmentalization, wherein the discrete subcellular partitioning of CaM/CMLs-exemplified by chloroplast and nuclear populations-facilitates the refined modulation of photosynthetic efficiency and transcriptional reprogramming. Furthermore, we discuss recent advances in manipulating CaM/CML-mediated pathways to enhance agronomic traits, including yield stability and stress tolerance. Ultimately, these insights provide a theoretical framework for leveraging calcium signaling components in molecular breeding programs aimed at developing elite crop varieties.