Cell cycle dependence of elicitor-induced signal transduction in tobacco BY-2 cells.
The molecular links between the cell cycle and defense responses in plants are largely unknown. Using synchronized tobacco BY-2 cells, we analyzed the cell cycle dependence of elicitor-induced defense responses. In synchronized cultured apoaequorin-expressing cells, the increase in cytosolic free Ca2+ induced by a proteinaceous elicitor, cryptogein, was greatly suppressed during the G2 and M phases in comparison with G1 or S phases. Treatment with cryptogein during the G1 or S phases also induced biphasic (rapid/transient and slow/prolonged) responses in activation of mitogen-activated protein kinases (MAPKs) and production of reactive oxygen species (ROS). In contrast, elicitor treatment during the G2 or M phases induced only a rapid and transient phase of MAPK activation and ROS production. Their slow and prolonged phases as well as expression of defense-related genes, cell cycle arrest and cell death were induced only after the cell cycle progressed to the G1 phase; removal of the elicitor before the start of the G1 phase inhibited these responses. These results suggest that although cryptogein recognition occurred at all phases of the cell cycle, the recognition during the S or G1 phases, but not at the G2 or M phases, induces the prolonged activation of MAPKs and the prolonged production of ROS, followed by cell cycle arrest, accumulation of defense-related gene transcripts and cell death. Elicitor signal transduction depends on the cell cycle and is regulated differently at each phase.
Kadota
Yasuhiro
Y
Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 Japan.
Watanabe
Takashi
T
Fujii
Shinsuke
S
Maeda
Yutaka
Y
Ohno
Ryoko
R
Higashi
Katsumi
K
Sano
Toshio
T
Muto
Shoshi
S
Hasezawa
Seiichiro
S
Kuchitsu
Kazuyuki
K
D000331:Aequorin / Q000378:metabolism; D020418:Algal Proteins / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005656:Fungal Proteins; D020935:MAP Kinase Signaling System / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*
D020418:Algal Proteins; D005656:Fungal Proteins; D017382:Reactive Oxygen Species; C061032:cryptogein protein, Phytophthora cryptogea; D000331:Aequorin; D048049:Extracellular Signal-Regulated MAP Kinases