Specific ER quality control components required for biogenesis of the plant innate immune receptor EFR.
Plant innate immunity depends in part on recognition of pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin, EF-Tu, and fungal chitin. Recognition is mediated by pattern-recognition receptors (PRRs) and results in PAMP-triggered immunity. EF-Tu and flagellin, and the derived peptides elf18 and flg22, are recognized in Arabidopsis by the leucine-rich repeat receptor kinases (LRR-RK), EFR and FLS2, respectively. To gain insights into the molecular mechanisms underlying PTI, we investigated EFR-mediated PTI using genetics. A forward-genetic screen for Arabidopsis elf18-insensitive (elfin) mutants revealed multiple alleles of calreticulin3 (CRT3), UDP-glucose glycoprotein glucosyl transferase (UGGT), and an HDEL receptor family member (ERD2b), potentially involved in endoplasmic reticulum quality control (ER-QC). Strikingly, FLS2-mediated responses were not impaired in crt3, uggt, and erd2b null mutants, revealing that the identified mutations are specific to EFR. A crt3 null mutant did not accumulate EFR protein, suggesting that EFR is a substrate for CRT3. Interestingly, Erd2b did not accumulate CRT3 protein, although they accumulate wild-type levels of other ER proteins. ERD2B seems therefore to be a specific HDEL receptor for CRT3 that allows its retro-translocation from the Golgi to the ER. These data reveal a previously unsuspected role of a specific subset of ER-QC machinery components for PRR accumulation in plant innate immunity.
Li
Jing
J
The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, United Kingdom.
Zhao-Hui
Chu
C
Batoux
Martine
M
Nekrasov
Vladimir
V
Roux
Milena
M
Chinchilla
Delphine
D
Zipfel
Cyril
C
Jones
Jonathan D G
JD
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D001483:Base Sequence; D037282:Calreticulin / Q000235:genetics / Q000276:immunology / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000235:genetics / Q000276:immunology / Q000502:physiology; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology; D009154:Mutation; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000276:immunology / Q000502:physiology; D044224:Pseudomonas syringae / Q000276:immunology / Q000472:pathogenicity; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D037282:Calreticulin; D017931:DNA Primers; C507138:ERD2 protein, Arabidopsis; D008565:Membrane Proteins; D005964:Glucosyltransferases; C072423:mannosylglycoprotein 1,3-glucosyltransferase; D011494:Protein Kinases; C411853:FLS2 protein, Arabidopsis