Abstract
Calcium is an essential element for plant growth and development, playing a crucial role in maintaining cell structure stability, signal transduction, and metabolic regulation. As a key secondary messenger, calcium regulates crop responses to various stresses, including drought, salt stress, and diseases. This review systematically summarizes the mechanisms by which calcium enhances crop stress resistance, with a focus on its core functions in cellular signal transduction, particularly the signaling pathways mediated by calcium-dependent protein kinases and calmodulin. The role of calcium under drought stress is specifically analyzed, covering its regulation of stomatal movement, optimization of water use efficiency, and modulation of drought-related gene networks. Furthermore, the review elaborates on the synergistic effects of calcium in maintaining ion homeostasis and enhancing the antioxidant system under salt stress, as well as its role in gene expression regulation. Additionally, the critical functions of calcium in the crop immune system are discussed, particularly the dynamic changes in calcium signaling upon pathogen invasion and its activation of defense-related genes. Based on recent research progress, this review explores the crosstalk between calcium and other signaling molecules and their integrative response mechanisms under complex stress conditions. Finally, the potential applications of calcium signaling pathways in molecular breeding and agricultural production are highlighted. This review aims to provide theoretical support for further elucidating the molecular mechanisms of calcium in crop stress resistance and serves as a reference for agricultural practices involving calcium signal regulation.
