Arabidopsis MAP kinase 4 regulates salicylic acid- and jasmonic acid/ethylene-dependent responses via EDS1 and PAD4.
Arabidopsis MPK4 has been implicated in plant defense regulation because mpk4 knockout plants exhibit constitutive activation of salicylic acid (SA)-dependent defenses, but fail to induce jasmonic acid (JA) defense marker genes in response to JA. We show here that mpk4 mutants are also defective in defense gene induction in response to ethylene (ET), and that they are more susceptible than wild-type (WT) to Alternaria brassicicola that induces the ET/JA defense pathway(s). Both SA-repressing and ET/JA-(co)activating functions depend on MPK4 kinase activity and involve the defense regulators EDS1 and PAD4, as mutations in these genes suppress de-repression of the SA pathway and suppress the block of the ET/JA pathway in mpk4. EDS1/PAD4 thus affect SA-ET/JA signal antagonism as activators of SA but as repressors of ET/JA defenses, and MPK4 negatively regulates both of these functions. We also show that the MPK4-EDS1/PAD4 branch of ET defense signaling is independent of the ERF1 transcription factor, and use comparative microarray analysis of ctr1, ctr1/mpk4, mpk4 and WT to show that MPK4 is required for induction of a small subset of ET-regulated genes. The regulation of some, but not all, of these genes involves EDS1 and PAD4.
Brodersen
Peter
P
Institute of Molecular Biology, Copenhagen University, Øster Farimagsgade 2A, DK-1353 Copenhagen K, Denmark.
Petersen
Morten
M
Bjørn Nielsen
Henrik
H
Zhu
Shijiang
S
Newman
Mari-Anne
MA
Shokat
Kevan M
KM
Rietz
Steffen
S
Parker
Jane
J
Mundy
John
J
D000528:Alternaria / Q000502:physiology; D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005030:Ethylenes / Q000494:pharmacology*; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D054883:Oxylipins; D010935:Plant Diseases / Q000382:microbiology; D020156:Salicylic Acid / Q000494:pharmacology*; D015533:Transcriptional Activation
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; C118837:EDS1 protein, Arabidopsis; D005030:Ethylenes; D054883:Oxylipins; C011006:jasmonic acid; C036216:ethylene; C436292:AtMPK4 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D002265:Carboxylic Ester Hydrolases; C400766:PAD4 protein, Arabidopsis; D020156:Salicylic Acid