Receptor quality control in the endoplasmic reticulum for plant innate immunity.
Pattern recognition receptors in eukaryotes initiate defence responses on detection of microbe-associated molecular patterns shared by many microbe species. The Leu-rich repeat receptor-like kinases FLS2 and EFR recognize the bacterial epitopes flg22 and elf18, derived from flagellin and elongation factor-Tu, respectively. We describe Arabidopsis 'priority in sweet life' (psl) mutants that show de-repressed anthocyanin accumulation in the presence of elf18. EFR accumulation and signalling, but not of FLS2, are impaired in psl1, psl2, and stt3a plants. PSL1 and PSL2, respectively, encode calreticulin3 (CRT3) and UDP-glucose:glycoprotein glycosyltransferase that act in concert with STT3A-containing oligosaccharyltransferase complex in an N-glycosylation pathway in the endoplasmic reticulum. However, EFR-signalling function is impaired in weak psl1 alleles despite its normal accumulation, thereby uncoupling EFR abundance control from quality control. Furthermore, salicylic acid-induced, but EFR-independent defence is weakened in psl2 and stt3a plants, indicating the existence of another client protein than EFR for this immune response. Our findings suggest a critical and selective function of N-glycosylation for different layers of plant immunity, likely through quality control of membrane-localized regulators.
Saijo
Yusuke
Y
Department of Plant Microbe Interactions, Max Planck Institute für Züchtungforschung, Köln, Germany. saijo@mpiz-koeln.mpg.de
Tintor
Nico
N
Lu
Xunli
X
Rauf
Philipp
P
Pajerowska-Mukhtar
Karolina
K
Häweker
Heidrun
H
Dong
Xinnian
X
Robatzek
Silke
S
Schulze-Lefert
Paul
P
D000483:Alleles; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000276:immunology* / Q000378:metabolism; D037282:Calreticulin / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D016695:Glycosyltransferases / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate; D010935:Plant Diseases / Q000276:immunology*; D011494:Protein Kinases / Q000276:immunology / Q000378:metabolism; D051192:Receptors, Pattern Recognition / Q000276:immunology* / Q000378:metabolism
D000872:Anthocyanins; D029681:Arabidopsis Proteins; D037282:Calreticulin; D051192:Receptors, Pattern Recognition; D016695:Glycosyltransferases; C545108:PSL2 protein, Arabidopsis; D011494:Protein Kinases; C411853:FLS2 protein, Arabidopsis