Autoimmunity in Arabidopsis acd11 is mediated by epigenetic regulation of an immune receptor

TY - JOUR

T1 - Autoimmunity in Arabidopsis acd11 is mediated by epigenetic regulation of an immune receptor

AU - Palma, Kristoffer

AU - Thorgrimsen, Stephan

AU - Malinovsky, Frederikke Gro

AU - Fiil, Berthe Katrine

AU - Nielsen, H Bjørn

AU - Brodersen, Peter

AU - Hofius, Daniel

AU - Petersen, Morten

AU - Mundy, John

PY - 2010/10

Y1 - 2010/10

N2 - Certain pathogens deliver effectors into plant cells to modify host protein targets and thereby suppress immunity. These target modifications can be detected by intracellular immune receptors, or Resistance (R) proteins, that trigger strong immune responses including localized host cell death. The accelerated cell death 11 (acd11) "lesion mimic" mutant of Arabidopsis thaliana exhibits autoimmune phenotypes such as constitutive defense responses and cell death without pathogen perception. ACD11 encodes a putative sphingosine transfer protein, but its precise role during these processes is unknown. In a screen for lazarus (laz) mutants that suppress acd11 death we identified two genes, LAZ2 and LAZ5. LAZ2 encodes the histone lysine methyltransferase SDG8, previously shown to epigenetically regulate flowering time via modification of histone 3 (H3). LAZ5 encodes an RPS4-like R-protein, defined by several dominant negative alleles. Microarray and chromatin immunoprecipitation analyses showed that LAZ2/SDG8 is required for LAZ5 expression and H3 lysine 36 trimethylation at LAZ5 chromatin to maintain a transcriptionally active state. We hypothesize that LAZ5 triggers cell death in the absence of ACD11, and that cell death in other lesion mimic mutants may also be caused by inappropriate activation of R genes. Moreover, SDG8 is required for basal and R protein-mediated pathogen resistance in Arabidopsis, revealing the importance of chromatin remodeling as a key process in plant innate immunity.

AB - Certain pathogens deliver effectors into plant cells to modify host protein targets and thereby suppress immunity. These target modifications can be detected by intracellular immune receptors, or Resistance (R) proteins, that trigger strong immune responses including localized host cell death. The accelerated cell death 11 (acd11) "lesion mimic" mutant of Arabidopsis thaliana exhibits autoimmune phenotypes such as constitutive defense responses and cell death without pathogen perception. ACD11 encodes a putative sphingosine transfer protein, but its precise role during these processes is unknown. In a screen for lazarus (laz) mutants that suppress acd11 death we identified two genes, LAZ2 and LAZ5. LAZ2 encodes the histone lysine methyltransferase SDG8, previously shown to epigenetically regulate flowering time via modification of histone 3 (H3). LAZ5 encodes an RPS4-like R-protein, defined by several dominant negative alleles. Microarray and chromatin immunoprecipitation analyses showed that LAZ2/SDG8 is required for LAZ5 expression and H3 lysine 36 trimethylation at LAZ5 chromatin to maintain a transcriptionally active state. We hypothesize that LAZ5 triggers cell death in the absence of ACD11, and that cell death in other lesion mimic mutants may also be caused by inappropriate activation of R genes. Moreover, SDG8 is required for basal and R protein-mediated pathogen resistance in Arabidopsis, revealing the importance of chromatin remodeling as a key process in plant innate immunity.

KW - Apoptosis Regulatory Proteins

KW - Arabidopsis

KW - Arabidopsis Proteins

KW - Autoimmunity

KW - Cell Death

KW - Chromatin Assembly and Disassembly

KW - Epigenesis, Genetic

KW - Gene Expression Regulation, Plant

KW - Histone-Lysine N-Methyltransferase

KW - Immunity, Innate

KW - Membrane Transport Proteins

KW - Receptors, Immunologic

U2 - 10.1371/journal.ppat.1001137

DO - 10.1371/journal.ppat.1001137

M3 - Journal article

C2 - 20949080

SN - 1553-7366

VL - 6

JO - P L o S Pathogens

JF - P L o S Pathogens

IS - 10

ER -