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Differential activation of four specific MAPK pathways by distinct elicitors
F Cardinale1, C Jonak, W Ligterink
1Institute of Microbiology and Genetics, Vienna Biocenter, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria.
The Journal of Biological Chemistry
|September 7, 2000
Summary
Plant cells activate multiple mitogen-activated protein kinases (MAPKs) in response to yeast elicitors. This study identifies specific MAPKs, like SIMK and MMK3, activated by microbial cues, revealing a complex plant defense signaling network.
Area of Science:
- Plant molecular biology
- Plant-microbe interactions
- Signal transduction
Background:
- Plant cells possess defense mechanisms activated by elicitors.
- Protein kinases, including MAPKs, play crucial roles in plant defense signaling.
- MAPKs are known to be activated by fungal and bacterial elicitors and pathogen infection.
Purpose of the Study:
- To investigate the activation of specific MAPKs in alfalfa cells upon treatment with yeast cell wall-derived elicitor (YE).
- To determine the kinetics and specificity of MAPK activation by different elicitor components.
- To identify novel roles for MMK2 and MMK3 in plant defense responses.
Main Methods:
- In-gel kinase assays to detect MAPK activity.
- Immunokinase assays using specific MAPK antibodies.
- Treatment of alfalfa cells with YE and chemically defined elicitors (chitin, N-acetylglucosamine oligomers, beta-glucan, ergosterol).
Main Results:
- Yeast elicitor (YE) rapidly and transiently activated 44- and 46-kDa MAPKs in alfalfa cells.
- Specific MAPKs, SIMK (46-kDa) and MMK3 (44-kDa), were predominantly activated by YE.
- Chitin, N-acetylglucosamine oligomers, beta-glucan, and ergosterol activated the four identified MAPKs to varying degrees and kinetics.
- This study provides the first evidence for external stimuli-induced activation of MMK2 and MMK3.
Conclusions:
- Plant cells utilize multiple MAPKs to perceive diverse microbial cues.
- The activation patterns suggest a complex signaling network involving SIMK, MMK3, MMK2, and SAMK in plant defense.
- MMK2 and MMK3 activation by external stimuli indicates their potential involvement in plant immunity beyond previously known functions.