Two calcium-dependent protein kinases, CPK4 and CPK11, regulate abscisic acid signal transduction in Arabidopsis.
Many biochemical approaches show functions of calcium-dependent protein kinases (CDPKs) in abscisic acid (ABA) signal transduction, but molecular genetic evidence linking defined CDPK genes with ABA-regulated biological functions at the whole-plant level has been lacking. Here, we report that ABA stimulated two homologous CDPKs in Arabidopsis thaliana, CPK4 and CPK11. Loss-of-function mutations of CPK4 and CPK11 resulted in pleiotropic ABA-insensitive phenotypes in seed germination, seedling growth, and stomatal movement and led to salt insensitivity in seed germination and decreased tolerance of seedlings to salt stress. Double mutants of the two CDPK genes had stronger ABA- and salt-responsive phenotypes than the single mutants. CPK4- or CPK11-overexpressing plants generally showed inverse ABA-related phenotypes relative to those of the loss-of-function mutants. Expression levels of many ABA-responsive genes were altered in the loss-of-function mutants and overexpression lines. The CPK4 and CPK11 kinases both phosphorylated two ABA-responsive transcription factors, ABF1 and ABF4, in vitro, suggesting that the two kinases may regulate ABA signaling through these transcription factors. These data provide in planta genetic evidence for the involvement of CDPK/calcium in ABA signaling at the whole-plant level and show that CPK4 and CPK11 are two important positive regulators in CDPK/calcium-mediated ABA signaling pathways.
Zhu
Sai-Yong
SY
China State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, 100094 Beijing, China.
Yu
Xiang-Chun
XC
Wang
Xiao-Jing
XJ
Zhao
Rui
R
Li
Yan
Y
Fan
Ren-Chun
RC
Shang
Yi
Y
Du
Shu-Yuan
SY
Wang
Xiao-Fang
XF
Wu
Fu-Qing
FQ
Xu
Yan-Hong
YH
Zhang
Xiao-Yan
XY
Zhang
Da-Peng
DP
D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D018525:Germination / Q000187:drug effects / Q000235:genetics; D015151:Immunoblotting; D047468:Immunoprecipitation; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology
D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004269:DNA, Bacterial; D010937:Plant Growth Regulators; D011494:Protein Kinases; D012965:Sodium Chloride; C036483:T-DNA; C000595436:CPK4 protein, Arabidopsis