A mitogen-activated protein kinase NtMPK4 activated by SIPKK is required for jasmonic acid signaling and involved in ozone tolerance via stomatal movement in tobacco.
The mitogen-activated protein kinase (MAPK) cascade is involved in responses to biotic and abiotic stress in plants. In this study, we isolated a new MAPK, NtMPK4, which is a tobacco homolog of Arabidopsis MPK4 (AtMPK4). NtMPK4 was activated by wounding along with two other wound-responsive tobacco MAPKs, WIPK and SIPK. We found that NtMPK4 was activated by salicylic acid-induced protein kinase kinase (SIPKK), which has been isolated as an SIPK-interacting MAPK kinase. In NtMPK4 activity-suppressed tobacco, wound-induced expression of jasmonic acid (JA)-responsive genes was inhibited. NtMPK4-silenced plants showed enhanced sensitivity to ozone. Inversely, transgenic tobacco plants, in which SIPKK or the constitutively active type SIPKK(EE) was overexpressed, exhibited greater responsiveness to wounding with enhanced resistance to ozone. We further found that NtMPK4 was expressed preferentially in epidermis, and the enhanced sensitivity to ozone in NtMPK4-silenced plants was caused by an abnormal regulation of stomatal closure in an ABA-independent manner. These results suggest that NtMPK4 is involved in JA signaling and in stomatal movement.
Gomi
Kenji
K
Plant Physiology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602 Japan.
Ogawa
Daisuke
D
Katou
Shinpei
S
Kamada
Hiroshi
H
Nakajima
Nobuyoshi
N
Saji
Hikaru
H
Soyano
Takashi
T
Sasabe
Michiko
M
Machida
Yasunori
Y
Mitsuhara
Ichiro
I
Ohashi
Yuko
Y
Seo
Shigemi
S
D003517:Cyclopentanes / Q000494:pharmacology*; D018744:DNA, Plant / Q000032:analysis; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017343:Genes, Plant; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D054883:Oxylipins; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
D003517:Cyclopentanes; D018744:DNA, Plant; D054883:Oxylipins; D010940:Plant Proteins; D010126:Ozone; C011006:jasmonic acid; D020928:Mitogen-Activated Protein Kinases; C404401:salicylic acid-induced protein kinase kinase; D020929:Mitogen-Activated Protein Kinase Kinases