CDPK-mediated abiotic stress signaling

Abstract

Calcium-dependent protein kinases (CDPKs) constitute a large multigene family in various plant species. CDPKs have been shown to have important roles in various physiological processes, including plant growth and development and abiotic and biotic stress responses in plants. Functional analysis using gain-of-function and loss-of-function mutants has revealed the biological function of CDPKs in planta. Several CDPKs have been shown to be essential factors in abiotic stress tolerance, positively or negatively regulating stress tolerance by modulating ABA signaling and reducing the accumulation of reactive oxygen species (ROS). This review summarizes recent results describing the biological function of CDPKs that are involved in abiotic stress tolerance.

Figure 1. (A) Structure of CDPK. The junction contains an autoinhibitory sequence that blocks the active site of the CDPK under basal state. The four bars within the calmodulin-like domain indicate the EF-hand Ca²⁺ binding motif. (B) Phylogenetic relationships among CDPKs from rice (OsCPK1-OsCPK29) and Arabidopsis (AtCPK1-AtCPK34). Red letters indicate CDPKs involved in abiotic stress signaling.

Figure 2. Summary of the function of CDPKs in ABA and abiotic stress responses, as reported by several authors.^,-,, The subcellular localization of each CDPK and the phenotypes of overexpression (OX) or knockout or knockdown (KO) lines are described. Red letters, Arabidopsis CDPKs; green letters, rice CDPKs; P, phosphorylation; ABF, ABA-responsive element binding factor; HSP1, a heat shock protein; OST1, open stomata 1 protein kinase.