The Arabidopsis thaliana TIR-NB-LRR R-protein, RPP1A; protein localization and constitutive activation of defence by truncated alleles in tobacco and Arabidopsis.
Specific recognition of Hyaloperonospora parasitica isolate Cala2 by Arabidopsis thaliana Ws-0 is mediated by the resistance gene RPP1A. Transient expression of different truncations of RPP1A in tobacco leaves revealed that its TIR-NB-ARC portion is sufficient to induce an elicitor-independent cell death. In stable transgenic lines of Arabidopsis, overexpression of the RPP1A TIR-NB-ARC domains (E12) using the 35S promoter leads to broad-spectrum resistance to virulent strains of H. parasitica and Pseudomonas syringae DC3000. The TIR-NB-ARC-mediated constitutive immunity is due to activation of the salicylic acid-dependent resistance pathway and is relieved by either a mutation in EDS1 or the presence of the salicylate hydroxylase gene, NahG. Growth of 35S::E12 plants is reduced, a phenotype observed in many constitutively resistant mutants. RPP1A carries a hydrophobic peptide at its N-terminus that directs the RPP1A protein into membranes, though it may not be the sole determinant mediating membrane association of RPP1A. Two-phase partitioning and sucrose density gradient sedimentation established that RPP1A resides in the endoplasmic reticulum and/or Golgi apparatus.
Michael Weaver
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Sainsbury Laboratory, John Innes Centre, Norwich Research Park Colney Lane, Norwich NR4 7UH, UK.
Swiderski
Michal R
MR
Li
Yan
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Jones
Jonathan D G
JD
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000235:genetics / Q000502:physiology*
D029681:Arabidopsis Proteins