Calcium-dependent protein kinases play an essential role in a plant defence response.
Calcium-dependent protein kinases (CDPKs) comprise a large family of serine/threonine kinases in plants and protozoans. We isolated two related CDPK cDNAs (NtCDPK2 and NtCDPK3) from Nicotiana tabacum. These CDPK transcripts are elevated after race-specific defence elicitation and hypo-osmotic stress. Transiently expressed myc-epitope-tagged NtCDPK2 in Nicotiana benthamiana and N.tabacum leaves showed a rapid transient interconversion to an activated form after elicitation and hypo-osmotic stress. The Avr9 race-specific elicitor caused a more pronounced and sustained response. This transition is due to phosphorylation of the CDPK. Immuno complex kinase assays with epitope-tagged NtCDPK2 showed that stress-induced phosphorylation and interconversion of NtCDPK2 correlates with an increase in enzymatic activity. The function of NtCDPK2 in plant defence was investigated by employing virus-induced gene silencing (VIGS) in N.benthamiana. CDPK-silenced plants showed a reduced and delayed hypersensitive response after race-specific elicitation in a gene-for-gene interaction, and lacked an accompanying wilting phenotype. Silencing correlated with loss of CDPK mRNA, whereas mRNA accumulation of mitogen-activated protein kinase WIPK remained unaltered.
Romeis
T
T
The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, Norfolk, UK. romeis@mpiz-koeln.mpg.de
Ludwig
A A
AA
Martin
R
R
Jones
J D
JD
D000595:Amino Acid Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured / Q000201:enzymology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004790:Enzyme Induction; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D020868:Gene Silencing; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis; D008969:Molecular Sequence Data; D005810:Multigene Family; D009997:Osmotic Pressure; D010641:Phenotype; D010766:Phosphorylation; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology; D018515:Plant Leaves / Q000201:enzymology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D017863:Potexvirus / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D020239:Receptor Cross-Talk; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
C085987:AVR4 protein, Cladosporium fulvum; D002135:Calcium-Binding Proteins; C109609:Cf protein, Lycopersicon esculentum; D018076:DNA, Complementary; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; D010940:Plant Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; C073605:AVR9 protein, Cladosporium fulvum; D011494:Protein Kinases; C410104:CDPK3 protein, Plasmodium falciparum; D020928:Mitogen-Activated Protein Kinases; C113423:WIPK protein, Nicotiana tabacum