Article

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: 7.39). 08/2008; 148(1):212-22. DOI: 10.1104/pp.108.120006
Source: PubMed

ABSTRACT 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.

0 Followers
 · 
138 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: In nature, plants constantly have to face pathogen attacks. However, plant disease rarely occurs due to efficient immune systems possessed by the host plants. Pathogens are perceived by two different recognition systems that initiate the so-called pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), both of which are accompanied by a set of induced defenses that usually repel pathogen attacks. Here we discuss the complex network of signaling pathways occurring during PTI, focusing on the involvement of mitogen-activated protein kinases. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.
    Molecular Plant 01/2015; DOI:10.1016/j.molp.2014.12.022 · 6.61 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Passiflora edulis is the major species of passionflowers grown worldwide, mainly for juice production and fresh fruit, in climates ranging from cool subtropi- cal (purple variety) to warm tropical (yellow variety). The bacterial leaf spot, caused by Xanthomonas axonopodis pv. passiflorae (Xap) can be a serious disease affecting passion fruit production in commercial orchards, particularly under moist field conditions. In this study we describe a first analysis of host gene expression in this pathosystem. We used suppression subtractive hybridiza- tion to construct two cDNA libraries enriched for transcripts induced and repressed by Xap, respectively, 24h post inoculation with a highly virulent strain. High-quality sequences were obtained resulting in 998 unisequences that were used for annotation. In accordance with BLASTX results performed by Blast2GO tool, 86.7% of the unisequences showed similarity to other plant species’ proteins related to different functional categories. Sixty-three tran- scripts were similar to Arabidopsis thaliana defence-related proteins identified in the PLAZA platform. In silico predicted protein–protein interactions were detected on the basis of the STRING database for 35 of the 63 defence-related proteins. At this early stage of interaction, a set of genes was selected from Blast2GO categorization results and analysed by quantitative PCR (qPCR). The expression profiles changed in response to the pathogen for 76% of these genes (48/63) and the differences in expression ratios ranged from 0.51-fold to 1.83-fold. In later stages of interactions (5 and 9 days post inoculation) when disease-associated symptoms were visible, qPCR analyses were performed for 14 genes selected from both libraries. The expression profiles of all genes were found to be changed by the pathogen. The gene that responded most strongly to the pathogen attack encodes a lipoxygenase 2. In inoculated plants, its expres- sion was induced 500-fold and 300-fold, 5 and 9 dpi, respectively, compared to controls, suggesting an important role of this gene in passion fruit defence. Moreover, we showed that most of the genes involved in well-known pathogen recognition signalling pathways were repressed by Xap and this lends support to the idea that the jasmonic acid signalling pathway fails to be activated during the first hours of interaction.
    Annals of Applied Biology 04/2015; 162. DOI:10.1111/aab.12215 · 1.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Programmed cell death (PCD) is a ubiquitous genetically regulated process consisting in an activation of finely controlled signaling pathways that lead to cellular suicide. Although some aspects of PCD control appear evolutionary conserved between plants, animals and fungi, the extent of conservation remains controversial. Over the last decades, identification and characterization of several lesion mimic mutants (LMM) has been a powerful tool in the quest to unravel PCD pathways in plants. Thanks to progress in molecular genetics, mutations causing the phenotype of a large number of LMM and their related suppressors were mapped, and the identification of the mutated genes shed light on major pathways in the onset of plant PCD such as (i) the involvements of chloroplasts and light energy, (ii) the roles of sphingolipids and fatty acids, (iii) a signal perception at the plasma membrane that requires efficient membrane trafficking, (iv) secondary messengers such as ion fluxes and ROS and (v) the control of gene expression as the last integrator of the signaling pathways.
    Frontiers in Plant Science 01/2015; 6:24. DOI:10.3389/fpls.2015.00024 · 3.64 Impact Factor

Full-text

Download
47 Downloads
Available from
May 16, 2014