Abstract
• Ca(2+) -dependent protein kinase (CDPK) is believed to be involved in abscisic acid (ABA) signaling, and several members of the Arabidopsis CDPK superfamily have been identified as positive ABA signaling regulators, but it remains unknown if CDPK negatively regulates ABA signaling. • Here, we investigated the function of an Arabidopsis (Arabidopsis thaliana) CDPK, CPK12, in ABA signaling pathway. • We generated Arabidopsis CPK12-RNAi lines, and observed that downregulation of CPK12 resulted in ABA hypersensitivity in seed germination and post-germination growth, and altered expression of a set of ABA-responsive genes. Expression assay showed that CPK12 was ubiquitously expressed and localized to both cytosol and nucleus. Biochemical assays showed that CPK12 interacted with, phosphorylated and stimulated a type 2C protein phosphatase ABI2, and phosphorylated two ABA-responsive transcription factors (ABF1 and ABF4) in vitro. • Our findings show that the Arabidopsis CPK12 is a negative ABA-signaling regulator in seed germination and post-germination growth, suggesting that different members of the CDPK family may constitute a regulation loop by functioning positively and negatively in ABA signal transduction.
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Abscisic Acid / metabolism*
-
Abscisic Acid / pharmacology
-
Arabidopsis / drug effects
-
Arabidopsis / enzymology*
-
Arabidopsis / growth & development*
-
Arabidopsis Proteins / genetics
-
Arabidopsis Proteins / metabolism*
-
Calcium-Calmodulin-Dependent Protein Kinases / genetics
-
Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
-
Cell Nucleus / drug effects
-
Cell Nucleus / enzymology
-
Cytosol / drug effects
-
Cytosol / enzymology
-
Down-Regulation / drug effects
-
Gene Expression Regulation, Plant / drug effects
-
Genes, Plant / genetics
-
Germination* / drug effects
-
Germination* / genetics
-
Phosphoprotein Phosphatases / metabolism
-
Phosphorylation / drug effects
-
Protein Binding / drug effects
-
Protein Kinases / genetics
-
Protein Kinases / metabolism*
-
Protein Transport / drug effects
-
RNA Interference / drug effects
-
RNA, Messenger / genetics
-
RNA, Messenger / metabolism
-
Seeds / drug effects
-
Seeds / enzymology
-
Seeds / genetics
-
Seeds / growth & development*
-
Signal Transduction* / drug effects
-
Signal Transduction* / genetics
-
Subcellular Fractions / drug effects
-
Subcellular Fractions / enzymology
-
Substrate Specificity / drug effects
-
Transcription Factors / metabolism
Substances
-
Arabidopsis Proteins
-
RNA, Messenger
-
Transcription Factors
-
Abscisic Acid
-
Protein Kinases
-
calcium-dependent protein kinase
-
CPK12 protein, Arabidopsis
-
Calcium-Calmodulin-Dependent Protein Kinases
-
ABI2 protein, Arabidopsis
-
Phosphoprotein Phosphatases