NRAMP genes function in Arabidopsis thaliana resistance to Erwinia chrysanthemi infection.
AtNRAMP3 and AtNRAMP4 are two Arabidopsis metal transporters sharing about 50% sequence identity with mouse NRAMP1. The NRAMP1/Slc11A1 metal ion transporter plays a crucial role in the innate immunity of animal macrophages targeted by intracellular bacterial pathogens. AtNRAMP3 and AtNRAMP4 localize to the vacuolar membrane. We found that AtNRAMP3 is upregulated in leaves challenged with the bacterial pathogens Pseudomonas syringae and Erwinia chrysanthemi, whereas AtNRAMP4 expression is not modified. Using single and double nramp3 and nramp4 mutants, as well as lines ectopically expressing either of these genes, we show that AtNRAMP3 and, to a lesser extent, AtNRAMP4 are involved in Arabidopsis thaliana resistance against the bacterial pathogen E. chrysanthemi. The susceptibility of the double nramp3 nramp4 mutant is associated with the reduced accumulation of reactive oxygen species and ferritin (AtFER1), an iron storage protein known to participate in A. thaliana defense. Interestingly, roots from infected plants accumulated transcripts of AtNRAMP3 as well as the iron-deficiency markers IRT1 and FRO2. This finding suggests the existence of a shoot-to-root signal reminiscent of an iron-deficiency signal activated by pathogen infection. Our data indicate that the functions of NRAMP proteins in innate immunity have been conserved between animals and plants.
Segond
Diego
D
Laboratoire des Interactions Plantes Pathogènes UMR 217 INRA/AgroParisTech/UPMC, 16 Rue Claude Bernard, 75231 Paris cedex 05, France.
Dellagi
Alia
A
Lanquar
Viviane
V
Rigault
Martine
M
Patrit
Oriane
O
Thomine
Sébastien
S
Expert
Dominique
D
D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D016974:Dickeya chrysanthemi / Q000254:growth & development*; D005293:Ferritins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007113:Immunity, Innate; D000090463:Iron Deficiencies; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D018517:Plant Roots / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000382:microbiology
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D018744:DNA, Plant; C408073:NRAMP4 protein, Arabidopsis; C408072:Nramp3 protein, Arabidopsis; D005293:Ferritins