title: Functional analysis of Arabidopsis immune-related MAPKs uncovers a role for MPK3 as negative regulator of inducible defences.
abstract: BACKGROUND
  Mitogen-activated protein kinases (MAPKs) are key regulators of immune responses in animals and plants. In Arabidopsis, perception of microbe-associated molecular patterns (MAMPs) activates the MAPKs MPK3, MPK4 and MPK6. Increasing information depicts the molecular events activated by MAMPs in plants, but the specific and cooperative contributions of the MAPKs in these signalling events are largely unclear.
  
  
  RESULTS
  In this work, we analyse the behaviour of MPK3, MPK4 and MPK6 mutants in early and late immune responses triggered by the MAMP flg22 from bacterial flagellin. A genome-wide transcriptome analysis reveals that 36% of the flg22-upregulated genes and 68% of the flg22-downregulated genes are affected in at least one MAPK mutant. So far MPK4 was considered as a negative regulator of immunity, whereas MPK3 and MPK6 were believed to play partially redundant positive functions in defence. Our work reveals that MPK4 is required for the regulation of approximately 50% of flg22-induced genes and we identify a negative role for MPK3 in regulating defence gene expression, flg22-induced salicylic acid accumulation and disease resistance to Pseudomonas syringae. Among the MAPK-dependent genes, 27% of flg22-upregulated genes and 76% of flg22-downregulated genes require two or three MAPKs for their regulation. The flg22-induced MAPK activities are differentially regulated in MPK3 and MPK6 mutants, both in amplitude and duration, revealing a highly interdependent network.
  
  
  CONCLUSIONS
  These data reveal a new set of distinct functions for MPK3, MPK4 and MPK6 and indicate that the plant immune signalling network is choreographed through the interplay of these three interwoven MAPK pathways.
authors: Nicolas
authors: N
authors: Frei dit Frey
authors: Ana Victoria
authors: AV
authors: Garcia
authors: Jean
authors: J
authors: Bigeard
authors: Rim
authors: R
authors: Zaag
authors: Eduardo
authors: E
authors: Bueso
authors: Marie
authors: M
authors: Garmier
authors: Stéphanie
authors: S
authors: Pateyron
authors: Marie-Ludivine
authors: ML
authors: de Tauzia-Moreau
authors: Véronique
authors: V
authors: Brunaud
authors: Sandrine
authors: S
authors: Balzergue
authors: Jean
authors: J
authors: Colcombet
authors: Sébastien
authors: S
authors: Aubourg
authors: Marie-Laure
authors: ML
authors: Martin-Magniette
authors: Heribert
authors: H
authors: Hirt
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000276:immunology; D029681:Arabidopsis Proteins / Q000502:physiology*; D060467:Disease Resistance; D005408:Flagellin / Q000276:immunology; D018506:Gene Expression Regulation, Plant / Q000276:immunology; D053263:Gene Regulatory Networks; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D057865:Plant Immunity; D044224:Pseudomonas syringae / Q000276:immunology; D015533:Transcriptional Activation; D059467:Transcriptome
chemical_list: D029681:Arabidopsis Proteins; D005408:Flagellin; C458516:AtMPK3 protein, Arabidopsis; C436292:AtMPK4 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases