The mitogen-activated protein kinase cascade MKK3-MPK6 is an important part of the jasmonate signal transduction pathway in Arabidopsis.
The plant hormone jasmonic acid (JA) plays a key role in the environmental stress responses and developmental processes of plants. Although ATMYC2/JASMONATE-INSENSITIVE1 (JIN1) is a major positive regulator of JA-inducible gene expression and essential for JA-dependent developmental processes in Arabidopsis thaliana, molecular mechanisms underlying the control of ATMYC2/JIN1 expression remain largely unknown. Here, we identify a mitogen-activated protein kinase (MAPK) cascade, MAPK KINASE 3 (MKK3)-MAPK 6 (MPK6), which is activated by JA in Arabidopsis. We also show that JA negatively controls ATMYC2/JIN1 expression, based on quantitative RT-PCR and genetic analyses using gain-of-function and loss-of-function mutants of the MKK3-MPK6 cascade. These results indicate that this kinase unit plays a key role in JA-dependent negative regulation of ATMYC2/JIN1 expression. Both positive and negative regulation by JA may be used to fine-tune ATMYC2/JIN1 expression to control JA signaling. Moreover, JA-regulated root growth inhibition is affected by mutations in the MKK3-MPK6 cascade, which indicates important roles in JA signaling. We provide a model explaining how MPK6 can convert three distinct signals - JA, pathogen, and cold/salt stress - into three different sets of responses in Arabidopsis.
Takahashi
Fuminori
F
Gene Discovery Research Group, RIKEN Plant Science Center, Tsukuba, Ibaraki 305-0074, Japan.
Yoshida
Riichiro
R
Ichimura
Kazuya
K
Mizoguchi
Tsuyoshi
T
Seo
Shigemi
S
Yonezawa
Masahiro
M
Maruyama
Kyonoshin
K
Yamaguchi-Shinozaki
Kazuko
K
Shinozaki
Kazuo
K
D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005030:Ethylenes / Q000494:pharmacology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D048371:MAP Kinase Kinase 3 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism; D054883:Oxylipins; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003517:Cyclopentanes; D005030:Ethylenes; C473611:MYC2 protein, Arabidopsis; D050505:Mutant Proteins; D054883:Oxylipins; D012333:RNA, Messenger; C011006:jasmonic acid; C036216:ethylene; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3