Salicylic acid-mediated innate immunity in Arabidopsis is regulated by SIZ1 SUMO E3 ligase.
Reversible modifications of target proteins by small ubiquitin-like modifier (SUMO) proteins are involved in many cellular processes in yeast and animals. Yet little is known about the function of sumoylation in plants. Here, we show that the SIZ1 gene, which encodes an Arabidopsis SUMO E3 ligase, regulates innate immunity. Mutant siz1 plants exhibit constitutive systemic-acquired resistance (SAR) characterized by elevated accumulation of salicylic acid (SA), increased expression of pathogenesis-related (PR) genes, and increased resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. Transfer of the NahG gene to siz1 plants results in reversal of these phenotypes back to wild-type. Analyses of the double mutants, npr1 siz1, pad4 siz1 and ndr1 siz1 revealed that SIZ1 controls SA signalling. SIZ1 interacts epistatically with PAD4 to regulate PR expression and disease resistance. Consistent with these observations, siz1 plants exhibited enhanced resistance to Pst DC3000 expressing avrRps4, a bacterial avirulence determinant that responds to the EDS1/PAD4-dependent TIR-NBS-type R gene. In contrast, siz1 plants were not resistant to Pst DC3000 expressing avrRpm1, a bacterial avirulence determinant that responds to the NDR1-dependent CC-NBS-type R gene. Jasmonic acid (JA)-induced PDF1.2 expression and susceptibility to Botrytis cinerea were unaltered in siz1 plants. Taken together, these results demonstrate that SIZ1 is required for SA and PAD4-mediated R gene signalling, which in turn confers innate immunity in Arabidopsis.
Lee
Jiyoung
J
Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnolgy Research Center and Environmental Biotechnology National Core Research Center, Graduate School of Gyeongsang National University, Jinju, Korea.
Nam
Jaesung
J
Park
Hyeong Cheol
HC
Na
Gunnam
G
Miura
Kenji
K
Jin
Jing Bo
JB
Yoo
Chan Yul
CY
Baek
Dongwon
D
Kim
Doh Hoon
DH
Jeong
Jae Cheol
JC
Kim
Donggiun
D
Lee
Sang Yeol
SY
Salt
David E
DE
Mengiste
Tesfaye
T
Gong
Qingqiu
Q
Ma
Shisong
S
Bohnert
Hans J
HJ
Kwak
Sang-Soo
SS
Bressan
Ray A
RA
Hasegawa
Paul M
PM
Yun
Dae-Jin
DJ
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000276:immunology*; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D020156:Salicylic Acid / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C118837:EDS1 protein, Arabidopsis; D002265:Carboxylic Ester Hydrolases; C400766:PAD4 protein, Arabidopsis; D008025:Ligases; C502552:SIZ1 protein, Arabidopsis; D020156:Salicylic Acid