Regulation of Stress Responses in Plants by Calcium Dependent Protein Kinases

Calcium-dependent protein kinases (CDPKs) represent the group of major calcium (Ca2+) sensors in plants. CDPKs comprise of peculiar structural features due to which they play a dual role of "Ca2+ sensor and responder" and decode the message from specific Ca2+ signature to phosphorylation events. Onset of most of the stresses results in increase in cytosolic Ca2+ level in plant cell. In depth functional analyses across plant species showed regulation of CDPK transcripts, activity, protein interactions and substrate targeting under biotic and abiotic stresses. Thus, vital role of CDPKs is proposed in transduction of stress triggered Ca2+ signaling to adaptive responses in plants. Genetic manipulations using CDPK genes could be vital in the agricultural biotechnology for imparting tolerance to biotic and abiotic stress, and better productivity. In this chapter, we provide an overview and update of CDPK gene family organization, CDPK domain structure and regulatory mechanism, the role of various CDPKs in abiotic stress, biotic stress signaling and responses in the model and crop plants.