Plant annexins: Structural diversity, evolution, and multifunctional roles in development and stress tolerance

Annexins are an evolutionarily conserved multigene family of Ca²⁺-dependent, phospholipid-binding proteins distributed across prokaryotes, fungi, plants, and animals. Structurally, all annexins share a conserved calcium-binding core domain along with variable amino-terminal regions that play crucial roles in post-translational modifications and protein-protein interactions. In plants, annexins have emerged as multifunctional proteins involved in growth, development, and adaptive responses to environmental challenges. Increasing experimental evidence indicates that plant annexins participate actively in abiotic stress tolerance by modulating calcium signaling, maintaining cellular redox homeostasis, and protecting membrane integrity. Several annexin members exhibit peroxidase activity and contribute to reactive oxygen species detoxification, thereby alleviating oxidative damage under stress conditions. Moreover, annexins have been shown to enhance tolerance to drought and salinity through osmotic adjustment and regulation of stress-responsive pathways. This review summarizes current knowledge on the structural and functional attributes of plant annexins and highlights their pivotal roles in mediating plant responses to abiotic stresses.