The MAP kinase substrate MKS1 is a regulator of plant defense responses

E. Andreasson, T. Jenkins, P. Brodersen, S. Thorgrimsen, N.H.T. Petersen, S.J. Zhu, J.L. Qiu, P. Micheelsen, A. Rocher, M. Petersen, M.A. Newman, Henrik Bjørn Nielsen, H. Hirt, I. Somssich, O. Mattsson, J. Mundy

    Research output: Contribution to journalJournal articleResearchpeer-review


    Arabidopsis MAP kinase 4 (MPK4) functions as a regulator of pathogen defense responses, because it is required for both repression of salicylic acid (SA)-dependent resistance and for activation of jasmonate (JA)-dependent defense gene expression. To understand MPK4 signaling mechanisms, we used yeast two-hybrid screening to identify the MPK4 substrate MKS1. Analyses of transgenic plants and genome-wide transcript profiling indicated that MKS1 is required for full SA-dependent resistance in mpk4 mutants, and that overexpression of MKS1 in wild-type plants is sufficient to activate SA-dependent resistance, but does not interfere with induction of a defense gene by JA. Further yeast two-hybrid screening revealed that MKS1 interacts with the WRKY transcription factors WRKY25 and WRKY33. WRKY25 and WRKY33 were shown to be in vitro substrates of MPK4, and a wrky33 knockout mutant was found to exhibit increased expression of the SA-related defense gene PR1. MKS1 may therefore contribute to MPK4-regulated defense activation by coupling the kinase to specific WRKY transcription factors.
    Original languageEnglish
    JournalEMBO Journal
    Issue number14
    Pages (from-to)2579-2589
    Publication statusPublished - 2005


    • disease resistance
    • protein kinase
    • phosphoserine

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