title: The Chromatin Remodeler SPLAYED Negatively Regulates SNC1-Mediated Immunity.
abstract: SNC1 (SUPPRESSOR OF NPR1, CONSTITUTIVE 1) is one of a suite of intracellular Arabidopsis NOD-like receptor (NLR) proteins which, upon activation, result in the induction of defense responses. However, the molecular mechanisms underlying NLR activation and the subsequent provocation of immune responses are only partially characterized. To identify negative regulators of NLR-mediated immunity, a forward genetic screen was undertaken to search for enhancers of the dwarf, autoimmune gain-of-function snc1 mutant. To avoid lethality resulting from severe dwarfism, the screen was conducted using mos4 (modifier of snc1, 4) snc1 plants, which display wild-type-like morphology and resistance. M2 progeny were screened for mutant, snc1-enhancing (muse) mutants displaying a reversion to snc1-like phenotypes. The muse9 mos4 snc1 triple mutant was found to exhibit dwarf morphology, elevated expression of the pPR2-GUS defense marker reporter gene and enhanced resistance to the oomycete pathogen Hyaloperonospora arabidopsidis Noco2. Via map-based cloning and Illumina sequencing, it was determined that the muse9 mutation is in the gene encoding the SWI/SNF chromatin remodeler SYD (SPLAYED), and was thus renamed syd-10. The syd-10 single mutant has no observable alteration from wild-type-like resistance, although the syd-4 T-DNA insertion allele displays enhanced resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola ES4326. Transcription of SNC1 is increased in both syd-4 and syd-10. These data suggest that SYD plays a subtle, specific role in the regulation of SNC1 expression and SNC1-mediated immunity. SYD may work with other proteins at the chromatin level to repress SNC1 transcription; such regulation is important for fine-tuning the expression of NLR-encoding genes to prevent unpropitious autoimmunity.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, V6T 1Z4, Canada Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, Canada These authors contributed equally to this work.
authors.forename: Kaeli C M
authors.initials: KC
authors.lastname: Johnson
authors.affiliation: Hunan Provincial Key Laboratory of Phytohormones and Growth Development, Hunan Agricultural University, Changsha, 410128, China These authors contributed equally to this work.
authors.forename: Shitou
authors.initials: S
authors.lastname: Xia
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Feng
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, V6T 1Z4, Canada Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, Canada xinli@msl.ubc.ca.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002843:Chromatin / Q000235:genetics; D042002:Chromatin Assembly and Disassembly; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D008954:Models, Biological; D016254:Mutagenesis, Insertional; D009868:Oomycetes / Q000502:physiology; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology*; D057865:Plant Immunity; D030821:Plants, Genetically Modified; D044224:Pseudomonas syringae / Q000502:physiology; D036226:Seedlings / Q000235:genetics / Q000276:immunology; D017422:Sequence Analysis, DNA
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin; C482739:SNC1 protein, Arabidopsis; D000251:Adenosine Triphosphatases; C452429:SPLAYED protein, Arabidopsis
keywords: Arabidopsis; Immunity; MUSE9; Resistance; SNC1; SPLAYED