NPR3 and NPR4 are receptors for the immune signal salicylic acid in plants.
Salicylic acid (SA) is a plant immune signal produced after pathogen challenge to induce systemic acquired resistance. It is the only major plant hormone for which the receptor has not been firmly identified. Systemic acquired resistance in Arabidopsis requires the transcription cofactor nonexpresser of PR genes 1 (NPR1), the degradation of which acts as a molecular switch. Here we show that the NPR1 paralogues NPR3 and NPR4 are SA receptors that bind SA with different affinities. NPR3 and NPR4 function as adaptors of the Cullin 3 ubiquitin E3 ligase to mediate NPR1 degradation in an SA-regulated manner. Accordingly, the Arabidopsis npr3 npr4 double mutant accumulates higher levels of NPR1, and is insensitive to induction of systemic acquired resistance. Moreover, this mutant is defective in pathogen effector-triggered programmed cell death and immunity. Our study reveals the mechanism of SA perception in determining cell death and survival in response to pathogen challenge.
Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Department of Biology, PO Box 90338, Duke University, Durham, North Carolina 27708, USA.
Zheng Qing
ZQ
Fu
Shunping
S
Yan
Abdelaty
A
Saleh
Wei
W
Wang
James
J
Ruble
Nodoka
N
Oka
Rajinikanth
R
Mohan
Steven H
SH
Spoel
Yasuomi
Y
Tada
Ning
N
Zheng
Xinnian
X
Dong
D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D029681:Arabidopsis Proteins; C105496:NPR1 protein, Arabidopsis; C517740:NPR3 protein, Arabidopsis; C502134:NPR4 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D020156:Salicylic Acid