1. Constitutively Active Mitogen-Activated Protein Kinase Versions Reveal Functions of Arabidopsis MPK4 in Pathogen Defense Signaling.
- Author
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Berriri, Souha, Garcia, Ana Victoria, Frey, Nicolas Frei dit, Rozhon, Wilfried, Pateyron, Stéphanie, Leonhardt, Nathalie, Montillet, Jean-Luc, Leung, Jeffrey, Hirt, Heribert, and Colcombet, Jean
- Subjects
MITOGEN-activated protein kinases ,ARABIDOPSIS ,REACTIVE oxygen species ,ARABIDOPSIS thaliana ,SALICYLIC acid - Abstract
Plant mitogen-activated protein kinases (MAPKs) are involved in important processes, including stress signaling and development. In a functional yeast screen, we identified mutations that render Arabidopsis thaliana MAPKs constitutively active (CA). Importantly, CA - MAPKs maintain their specificity toward known activators and substrates. As a proof-of-concept, Arabidopsis MAPK4 (MPK4) function in plant immunity was investigated. In agreement with the phenotype of mpk4 mutants, CA -MPK4 plants were compromised in pathogen-induced salicylic acid accumulation and disease resistance. MPK4 activity was found to negatively regulate pathogen-associated molecular pattern-induced reactive oxygen species production but had no impact on callose deposition, indicating that CA -MPK4 allows discriminating between processes regulated by MPK4 activity from processes indirectly affected by mpk4 mutation. Finally, MPK4 activity was also found to compromise effector-triggered immunity conditioned by the Toll Interleukin-1 Receptor–nucleotide binding (NB)–Leu-rich repeat (LRR) receptors RPS4 and RPP4 but not by the coiled coil– NB - LRR receptors RPM1 and RPS2. Overall, these data reveal important insights on how MPK4 regulates plant defenses and establishes that CA - MAPKs offer a powerful tool to analyze the function of plant MAPK pathways. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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