Membrane-associated ubiquitin ligase saul1 suppresses temperature- And humidity-dependent autoimmunity in arabidopsis

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Autor/in:
Erscheinungsjahr:
2016
Medientyp:
Text
Schlagworte:
  • Ligases
  • Ubiquitin
  • Ubiquitin ligases
  • Arabidopsis
  • Plants
  • Genes
  • Ligases
  • Ubiquitin
  • Ubiquitin ligases
  • Arabidopsis
  • Plants
  • Genes
Beschreibung:
  • Plants have evolved elaborate mechanisms to regulate pathogen defense. Imbalances in this regulation may result in autoimmune responses that are affecting plant growth and development. In Arabidopsis, SAUL1 encodes a plant U-box ubiquitin ligase and regulates senescence and cell death. Here, we show that saull-1 plants exhibit characteristics of an autoimmune mutant. A decrease in relative humidity or temperature resulted in reduced growth and systemic lesioning of saull-1 rosettes. These physiological changes are associated with increased expression of salicylic acid dependent and pathogenesis-related (PR) genes. Consistently, resistance of saull-1 plants against Pseudomonas syringae pv. maculicola ES4326, P. syringae pv. tomato DC3000, or Hyaloperonospora arabidopsidis Noco2 was enhanced. Transmission electron microscopy revealed alterations in saull-1 chloroplast ultrastructure and cell-wall depositions. Confocal analysis on aniline blue stained leaf sections and cellular universal micro spectrophotometry further showed that these cell-wall depositions contain callose and lignin. To analyze signaling downstream of SAUL1, we performed epistasis analyses between saull-1 and mutants in the EDS1/PAD4/SAG101 hub. All phenotypes observed in saull-1 plants at low temperature were dependent on EDS1 and PAD4 but not SAG101. Taken together, SAUL1 negatively regulates immunity upstream of EDS1/PAD4, likely through the degradation of an unknown activator of the pathway.
  • Plants have evolved elaborate mechanisms to regulate pathogen defense. Imbalances in this regulation may result in autoimmune responses that are affecting plant growth and development. In Arabidopsis, SAUL1 encodes a plant U-box ubiquitin ligase and regulates senescence and cell death. Here, we show that saul1-1 plants exhibit characteristics of an autoimmune mutant. A decrease in relative humidity or temperature resulted in reduced growth and systemic lesioning of saul1-1 rosettes. These physiological changes are associated with increased expression of salicylic acid-dependent and pathogenesis-related (PR) genes. Consistently, resistance of saul1-1 plants against Pseudomonas syringae pv. maculicola ES4326, P. syringae pv. tomato DC3000, or Hyaloperonospora arabidopsidis Noco2 was enhanced. Transmission electron microscopy revealed alterations in saul1-1 chloroplast ultrastructure and cell-wall depositions. Confocal analysis on aniline blue-stained leaf sections and cellular universal micro spectrophotometry further showed that these cell-wall depositions contain callose and lignin. To analyze signaling downstream of SAUL1, we performed epistasis analyses between saul1-1 and mutants in the EDS1/PAD4/SAG101 hub. All phenotypes observed in saul1-1 plants at low temperature were dependent on EDS1 and PAD4 but not SAG101. Taken together, SAUL1 negatively regulates immunity upstream of EDS1/PAD4, likely through the degradation of an unknown activator of the pathway.
Lizenz:
  • info:eu-repo/semantics/openAccess
Quellsystem:
Forschungsinformationssystem der UHH
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oai:www.edit.fis.uni-hamburg.de:publications/35227b7d-762d-4bc5-a4f4-45f6040e8857