An Innate Immunity Pathway in the Moss Physcomitrella patens.
MAP kinase (MPK) cascades in Arabidopsis thaliana and other vascular plants are activated by developmental cues, abiotic stress, and pathogen infection. Much less is known of MPK functions in nonvascular land plants such as the moss Physcomitrella patens Here, we provide evidence for a signaling pathway in P. patens required for immunity triggered by pathogen associated molecular patterns (PAMPs). This pathway induces rapid growth inhibition, a novel fluorescence burst, cell wall depositions, and accumulation of defense-related transcripts. Two P. patens MPKs (MPK4a and MPK4b) are phosphorylated and activated in response to PAMPs. This activation in response to the fungal PAMP chitin requires a chitin receptor and one or more MAP kinase kinase kinases and MAP kinase kinases. Knockout lines of MPK4a appear wild type but have increased susceptibility to the pathogenic fungi Botrytis cinerea and Alternaria brassisicola Both PAMPs and osmotic stress activate some of the same MPKs in Arabidopsis. In contrast, abscisic acid treatment or osmotic stress of P. patens does not activate MPK4a or any other MPK, but activates at least one SnRK2 kinase. Signaling via MPK4a may therefore be specific to immunity, and the moss relies on other pathways to respond to osmotic stress.
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Simon
S
Bressendorff
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Raquel
R
Azevedo
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Chandra Shekar
CS
Kenchappa
Departamento de Biología Molecular, Instituto de Investigaciones Biológicas Clemente Estable, 11600 Montevideo, Uruguay.
Inés
I
Ponce de León
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Jakob V
JV
Olsen
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Magnus Wohlfahrt
MW
Rasmussen
Department of Plant and Environmental Science, University of Copenhagen, 1871 Frederiksberg C, Denmark.
Gitte
G
Erbs
Department of Plant and Environmental Science, University of Copenhagen, 1871 Frederiksberg C, Denmark.
Mari-Anne
MA
Newman
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark.
Morten
M
Petersen
Department of Molecular Biology, University of Copenhagen, 2200 Copenhagen, Denmark mundy@bio.ku.dk.
John
J
Mundy
D000528:Alternaria / Q000276:immunology / Q000472:pathogenicity; D017360:Arabidopsis / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D020171:Botrytis / Q000276:immunology / Q000472:pathogenicity; D019068:Bryopsida / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology*; D009997:Osmotic Pressure / Q000187:drug effects; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
D000069452:Pathogen-Associated Molecular Pattern Molecules; D010940:Plant Proteins