ETHYLENE INSENSITIVE3 and ETHYLENE INSENSITIVE3-LIKE1 repress SALICYLIC ACID INDUCTION DEFICIENT2 expression to negatively regulate plant innate immunity in Arabidopsis.
Pathogen/microbe-associated molecular patterns (PAMPs/MAMPs) trigger plant immunity that forms the first line inducible defenses in plants. The regulatory mechanism of MAMP-triggered immunity, however, is poorly understood. Here, we show that Arabidopsis thaliana transcription factors ETHYLENE INSENSITIVE3 (EIN3) and ETHYLENE INSENSITIVE3-LIKE1 (EIL1), previously known to mediate ethylene signaling, also negatively regulate PAMP-triggered immunity. Plants lacking EIN3 and EIL1 display enhanced PAMP defenses and heightened resistance to Pseudomonas syringae bacteria. Conversely, plants overaccumulating EIN3 are compromised in PAMP defenses and exhibit enhanced disease susceptibility to Pseudomonas syringae. Microarray analysis revealed that EIN3 and EIL1 negatively control PAMP response genes. Further analyses indicated that SALICYLIC ACID INDUCTION DEFICIENT2 (SID2), which encodes isochorismate synthase required for pathogen-induced biosynthesis of salicylic acid (SA), is a key target of EIN3 and EIL1. Consistent with this, the ein3-1 eil1-1 double mutant constitutively accumulates SA in the absence of pathogen attack, and a mutation in SID2 restores normal susceptibility in the ein3 eil1 double mutant. EIN3 can specifically bind SID2 promoter sequence in vitro and in vivo. Taken together, our data provide evidence that EIN3/EIL1 directly target SID2 to downregulate PAMP defenses.
Chen
Huamin
H
School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China.
Xue
Li
L
Chintamanani
Satya
S
Germain
Hugo
H
Lin
Huiqiong
H
Cui
Haitao
H
Cai
Run
R
Zuo
Jianru
J
Tang
Xiaoyan
X
Li
Xin
X
Guo
Hongwei
H
Zhou
Jian-Min
JM
D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology*; D015151:Immunoblotting; D019751:Intramolecular Transferases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D011401:Promoter Regions, Genetic; D044224:Pseudomonas syringae / Q000472:pathogenicity; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C494589:EIL1 protein, Arabidopsis; C106987:EIN3 protein, Arabidopsis; D009687:Nuclear Proteins; D014157:Transcription Factors; D019751:Intramolecular Transferases; C058486:isochorismate synthase