title: Salicylic acid-mediated innate immunity in Arabidopsis is regulated by SIZ1 SUMO E3 ligase.
abstract: 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.
authors.affiliation: 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.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Jaesung
authors.initials: J
authors.lastname: Nam
authors.forename: Hyeong Cheol
authors.initials: HC
authors.lastname: Park
authors.forename: Gunnam
authors.initials: G
authors.lastname: Na
authors.forename: Kenji
authors.initials: K
authors.lastname: Miura
authors.forename: Jing Bo
authors.initials: JB
authors.lastname: Jin
authors.forename: Chan Yul
authors.initials: CY
authors.lastname: Yoo
authors.forename: Dongwon
authors.initials: D
authors.lastname: Baek
authors.forename: Doh Hoon
authors.initials: DH
authors.lastname: Kim
authors.forename: Jae Cheol
authors.initials: JC
authors.lastname: Jeong
authors.forename: Donggiun
authors.initials: D
authors.lastname: Kim
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: David E
authors.initials: DE
authors.lastname: Salt
authors.forename: Tesfaye
authors.initials: T
authors.lastname: Mengiste
authors.forename: Qingqiu
authors.initials: Q
authors.lastname: Gong
authors.forename: Shisong
authors.initials: S
authors.lastname: Ma
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Bohnert
authors.forename: Sang-Soo
authors.initials: SS
authors.lastname: Kwak
authors.forename: Ray A
authors.initials: RA
authors.lastname: Bressan
authors.forename: Paul M
authors.initials: PM
authors.lastname: Hasegawa
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
mesh_terms: 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*
chemical_list: 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