Arabidopsis Mitogen-Activated Protein Kinase Kinases MKK1 and MKK2 have overlapping functions in defense signaling mediated by MEKK1, MPK4, and MKS1

Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark.
Plant physiology (Impact Factor: 6.84). 08/2008; 148(1):212-22. DOI: 10.1104/pp.108.120006
Source: PubMed


The Arabidopsis (Arabidopsis thaliana) MKK1 and MKK2 mitogen-activated protein kinase kinases have been implicated in biotic and abiotic stress responses as part of a signaling cascade including MEKK1 and MPK4. Here, the double loss-of-function mutant (mkk1/2) of MKK1 and MKK2 is shown to have marked phenotypes in development and disease resistance similar to those of the single mekk1 and mpk4 mutants. Because mkk1 or mkk2 single mutants appear wild type, basal levels of MPK4 activity are not impaired in them, and MKK1 and MKK2 are in part functionally redundant in unchallenged plants. These findings are confirmed and extended by biochemical and molecular analyses implicating the kinases in jasmonate- and salicylate-dependent defense responses, mediated in part via the MPK4 substrate MKS1. In addition, transcriptome analyses delineate overlapping and specific effects of the kinases on global gene expression patterns demonstrating both redundant and unique functions for MKK1 and MKK2.

Download full-text


Available from: Lu Zhou
  • Source
    • "To determine the downstream signaling event following the CD2-0 recognition, MAPK activation by CD2-0 was investigated. It has reported that MAPK3, MAPK4, and MAPK6 were activated after flg22 treatment in Arabidopsis (Asai et al. 2002; Ichimura et al. 2006; Qiu et al. 2008). Arabidopsis suspension cells were treated with either flg22 or CD2-0, and the activation of MAPK was detected by using an antip44/42-ERK antibody. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Flagellin from the rice avirulent N1141 strain of Acidovorax avenae, functions as a pathogen-associated molecular pattern (PAMP) and induces PAMP-triggered immunity (PTI) in rice. To study the recognition mechanism of flagellin in rice, we attempted to define the region(s) of the flagellin protein required to activate the PTI response. Based on domain classification, we produced four fragments of N1141 flagellin: N-terminal D0, D1 and D2 domains (ND0-2), N-terminal D2, D3, and C-terminal D2 domains (ND2-CD2), C-terminal D2, D1, and D0 domains (CD2-0), and C-terminal D2 and D1 domains (CD2-1). The C-terminal CD2-1 and CD2-0 fragments induced PTI responses in cultured rice cells. Synthetic flg22, which is sufficient to produce the flagellin response in Arabidopsis, and the N-terminal flagellin fragments containing flg22 region elicited very weak immune responses in rice. OsFLS2, the rice ortholog of AtFLS2 which mediates flg22 recognition, was not involved in CD2-0 or CD2-1 recognition in rice. In addition, CD2-0 triggered resistance to coinfection with pathogenic bacteria. Taken together, these data suggest that rice mainly recognizes flagellin CD2-1 by a receptor distinct from OsFLS2, and that this epitope recognition leads to PTI responses.
    Full-text · Article · Jan 2015 · Molecular Plant-Microbe Interactions
  • Source
    • "Regulation of transcriptional complexes by MAPK cascades MAPK cascades are important signaling pathways that link stimuli to downstream responses via phosphorylation of substrates including TFs, and many studies show their implications in plant immunity (Meng & Zhang, 2013). For instance, Arabidopsis AtMPK3 and AtMPK6 are activated by the upstream MAPK kinases AtMKK4 and AtMKK5, whereas AtMPK4 and likely AtMPK11 are regulated by AtMKK1 and AtMKK2, which are activated by the upstream MAPK kinase kinase AtMEKK1 (Asai et al., 2002; Ichimura et al., 2006; Meszaros et al., 2006; Nakagami et al., 2006; Suarez-Rodriguez et al., 2007; Qiu et al., 2008b; Bethke et al., 2012). Although the mechanisms by which these MAPK cascades are activated during immunity remain to be "
    [Show abstract] [Hide abstract]
    ABSTRACT: I. II. III. IV. V. References SUMMARY: Next to numerous abiotic stresses, plants are constantly exposed to a variety of pathogens within their environment. Thus, their ability to survive and prosper during the course of evolution was strongly dependent on adapting efficient strategies to perceive and to respond to such potential threats. It is therefore not surprising that modern plants have a highly sophisticated immune repertoire consisting of diverse signal perception and intracellular signaling pathways. This signaling network is intricate and deeply interconnected, probably reflecting the diverse lifestyles and infection strategies used by the multitude of invading phytopathogens. Moreover it allows signal communication between developmental and defense programs thereby ensuring that plant growth and fitness are not significantly retarded. How plants integrate and prioritize the incoming signals and how this information is transduced to enable appropriate immune responses is currently a major research area. An important finding has been that pathogen-triggered cellular responses involve massive transcriptional reprogramming within the host. Additional key observations emerging from such studies are that transcription factors (TFs) are often sites of signal convergence and that signal-regulated TFs act in concert with other context-specific TFs and transcriptional co-regulators to establish sensory transcription regulatory networks required for plant immunity. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.
    Full-text · Article · Jan 2015 · New Phytologist
  • Source
    • "Group A includes Arabidopsis thaliana AtMKK1, AtMKK2 and AtMKK6. AtMKK1 and AtMKK2 act upstream of AtMAPK4 in response to cold, salinity and pathogens [8], [9]. AtMKK6 is involved in cytokinesis control and cell-cycle regulation [10]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mitogen-activated protein kinase (MAPK) cascades have crucial roles in the regulation of plant development and in plant responses to stress. Plant recognition of pathogen-associated molecular patterns or pathogen-derived effector proteins has been shown to trigger activation of several MAPKs. This then controls defence responses, including synthesis and/or signalling of defence hormones and activation of defence related genes. The MAPK cascade genes are highly complex and interconnected, and thus the precise signalling mechanisms in specific plant-pathogen interactions are still not known. Here we investigated the MAPK signalling network involved in immune responses of potato (Solanum tuberosum L.) to Potato virus Y, an important potato pathogen worldwide. Sequence analysis was performed to identify the complete MAPK kinase (MKK) family in potato, and to identify those regulated in the hypersensitive resistance response to Potato virus Y infection. Arabidopsis has 10 MKK family members, of which we identified five in potato and tomato (Solanum lycopersicum L.), and eight in Nicotiana benthamiana. Among these, StMKK6 is the most strongly regulated gene in response to Potato virus Y. The salicylic acid treatment revealed that StMKK6 is regulated by the hormone that is in agreement with the salicylic acid-regulated domains found in the StMKK6 promoter. The involvement of StMKK6 in potato defence response was confirmed by localisation studies, where StMKK6 accumulated strongly only in Potato-virus-Y-infected plants, and predominantly in the cell nucleus. Using a yeast two-hybrid method, we identified three StMKK6 targets downstream in the MAPK cascade: StMAPK4_2, StMAPK6 and StMAPK13. These data together provide further insight into the StMKK6 signalling module and its involvement in plant defence.
    Full-text · Article · Aug 2014 · PLoS ONE
Show more