Characterization of the ZmCK1 Gene Encoding a Calcium-Dependent Protein Kinase Responsive to Multiple Abiotic Stresses in Maize

Abstract

Calcium-dependent protein kinases (CDPKs) play a vital regulatory role in abiotic stress responses in plants. We isolated the ZmCK1 gene encoding a CDPK from maize seedlings. The predicted ZmCK1 protein contains a typical Ser/Thr protein kinase domain and four EF-hand calcium-binding motifs in its N-terminal and C-terminal halves, respectively. The catalytic and regulatory domains were linked by a well-conserved junction domain. A ZmCK1::hGFP fusion protein was found to localize into the cytoplasma and nucleus upon introduction into Arabidopsis mesophyll protoplasts. ZmCK1 transcription was highly activated by salt and cold, and moderately by drought and exogenous ABA in maize seedling. Isolation of the ZmCK1 promoter revealed some cis-acting elements responding to stresses. Overexpression of ZmCK1 improved drought, salt, and cold stress tolerance in transgenic Arabidopsis plants. Our results suggested that ZmCK1 produces a functional kinase that may play a regulatory role in abiotic stress response.