Constitutively active Arabidopsis MAP Kinase 3 triggers defense responses involving salicylic acid and SUMM2 resistance protein

Baptiste Genot, Julien Lang, Souha Berriri, Marie Garmier, Françoise Gilard, Stéphanie Pateyron, Katrien Haustraete, Dominique Van Der Straeten, Heribert Hirt, Jean Colcombet

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45 Scopus citations


Mitogen-activated protein kinases (MAPKs) are important regulators of plant immunity. Most of the knowledge about the function of these pathways is derived from loss-of-function approaches. Using a gain-of-function approach, we investigated the responses controlled by a constitutively active (CA) MPK3 in Arabidopsis thaliana. CA-MPK3 plants are dwarfed and display a massive de-repression of defense genes associated with spontaneous cell death as well as accumulation of reactive oxygen species (ROS), phytoalexins and the stress-related hormones ethylene and salicylic acid (SA). Remarkably CA-MPK3/sid2 and CA-MPK3/ein2-50 lines which are impaired in SA synthesis and ethylene signaling, respectively, retain most of the CA-MPK3-associated phenotypes, indicating that constitutive activity of MPK3 can bypass SA and ethylene signaling to activate defense responses. A comparative analysis of the molecular phenotypes of CA-MPK3 and mpk4 autoimmunity suggested convergence between the MPK3 and MPK4-guarding modules. In support of this model, CA-MPK3 crosses with summ1 and summ2, two known suppressors of mpk4, resulted in a partial reversion of the CA-MPK3 phenotypes. Overall, our data unravel a novel mechanism by which the MAPK signaling network contributes to a robust defense response system.
Original languageEnglish (US)
Pages (from-to)1238-1249
Number of pages12
JournalPlant Physiology
Issue number2
StatePublished - Apr 11 2017

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Yuelin Zhang and Jane Parker for summ1/2 and sid2 mutants respectively, Filip Vandenbussche for ethylene measurement and Jean Bigeard for helpful discussions and his critical reading of the manuscript. This work was largely supported by the Institut National de Recherche Agronomique (INRA),the Agence Nationale de la echerche (ANR) and a grant (LabEx Saclay Plant Sciences-SPS, reference ANR-10-LABX-0040-SPS), managed by the French National Research Agency under an Investments for the Future program (reference n°ANR-11-IDEX-0003-02). B.G. was supported by French Ministry of Research PhD fellowship. D.V.D.S. gratefully acknowledges the Research Foundation Flanders (FWO G.0656.13N) and Ghent University (Bijzonder Onderzoeksfonds, BOF-BAS) for financial support.


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