title: A TIR-NBS protein encoded by Arabidopsis Chilling Sensitive 1 (CHS1) limits chloroplast damage and cell death at low temperature.
abstract: Survival of plants at low temperature depends on mechanisms for limiting physiological damage and maintaining growth. We mapped the chs1-1 (chilling sensitive1-1) mutation in Arabidopsis accession Columbia to the TIR-NBS gene At1g17610. In chs1-1, a single amino acid exchange at the CHS1 N-terminus close to the conserved TIR domain creates a stable mutant protein that fails to protect leaves against chilling stress. The sequence of another TIR-NBS gene (At5g40090) named CHL1 (CHS1-like 1) is related to that of CHS1. Over-expression of CHS1 or CHL1 alleviates chilling damage and enhances plant growth at moderate (24°C) and chilling (13°C) temperatures, suggesting a role for both proteins in growth homeostasis. chs1-1 mutants show induced salicylic acid production and defense gene expression at 13°C, indicative of autoimmunity. Genetic analysis of chs1-1 in combination with defense pathway mutants shows that chs1-1 chilling sensitivity requires the TIR-NBS-LRR and basal resistance regulators encoded by EDS1 and PAD4 but not salicylic acid. By following the timing of metabolic, physiological and chloroplast ultrastructural changes in chs1-1 leaves during chilling, we have established that alterations in photosynthetic complexes and thylakoid membrane integrity precede leaf cell death measured by ion leakage. At 24°C, the chs1-1 mutant appears normal but produces a massive necrotic response to virulent Pseudomonas syringae pv. tomato infection, although this does not affect bacterial proliferation. Our results suggest that CHS1 acts at an intersection between temperature sensing and biotic stress pathway activation to maintain plant performance over a range of conditions.
authors.affiliation: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115, Bonn, Germany.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Zbierzak
authors.forename: Svetlana
authors.initials: S
authors.lastname: Porfirova
authors.forename: Thomas
authors.initials: T
authors.lastname: Griebel
authors.forename: Michael
authors.initials: M
authors.lastname: Melzer
authors.forename: Jane E
authors.initials: JE
authors.lastname: Parker
authors.forename: Peter
authors.initials: P
authors.lastname: Dörmann
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000502:physiology / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D016923:Cell Death; D002736:Chloroplasts / Q000378:metabolism* / Q000648:ultrastructure; D002874:Chromosome Mapping; D003080:Cold Temperature / Q000009:adverse effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D060467:Disease Resistance; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D010935:Plant Diseases / Q000276:immunology*; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000502:physiology / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D044224:Pseudomonas syringae / Q000502:physiology; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000032:analysis / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; C587982:CHS1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C118837:EDS1 protein, Arabidopsis; D011971:Receptors, Immunologic; D002265:Carboxylic Ester Hydrolases; C400766:PAD4 protein, Arabidopsis; D020156:Salicylic Acid
keywords: Arabidopsis thaliana; EDS1; bacterial infection; galactolipids; growth homeostasis; tocopherol