ANNEXIN 8 negatively regulates RPW8.1-mediated cell death and disease resistance in Arabidopsis

J Integr Plant Biol. 2021 Feb;63(2):378-392. doi: 10.1111/jipb.13025.

Abstract

Study on the regulation of broad-spectrum resistance is an active area in plant biology. RESISTANCE TO POWDERY MILDEW 8.1 (RPW8.1) is one of a few broad-spectrum resistance genes triggering the hypersensitive response (HR) to restrict multiple pathogenic infections. To address the question how RPW8.1 signaling is regulated, we performed a genetic screen and tried to identify mutations enhancing RPW8.1-mediated HR. Here, we provided evidence to connect an annexin protein with RPW8.1-mediated resistance in Arabidopsis against powdery mildew. We isolated and characterized Arabidopsis b7-6 mutant. A point mutation in b7-6 at the At5g12380 locus resulted in an amino acid substitution in ANNEXIN 8 (AtANN8). Loss-of-function or RNA-silencing of AtANN8 led to enhanced expression of RPW8.1, RPW8.1-dependent necrotic lesions in leaves, and defense against powdery mildew. Conversely, over-expression of AtANN8 compromised RPW8.1-mediated disease resistance and cell death. Interestingly, the mutation in AtANN8 enhanced RPW8.1-triggered H2 O2 . In addition, mutation in AtANN8 led to hypersensitivity to salt stress. Together, our data indicate that AtANN8 is involved in multiple stress signaling pathways and negatively regulates RPW8.1-mediated resistance against powdery mildew and cell death, thus linking ANNEXIN's function with plant immunity.

Keywords: AtANN8; H2O2; RPW8.1; cell death; disease resistance; hypersensitive response; powdery mildew.

MeSH terms

  • Adaptation, Physiological
  • Amino Acid Sequence
  • Annexins / chemistry
  • Annexins / genetics
  • Annexins / metabolism*
  • Arabidopsis / cytology
  • Arabidopsis / genetics
  • Arabidopsis / immunology*
  • Arabidopsis / microbiology*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Ascomycota / physiology
  • Cell Death
  • Disease Resistance*
  • Endoplasmic Reticulum / metabolism
  • Enhancer Elements, Genetic / genetics
  • Gene Expression Regulation, Plant
  • Gene Silencing
  • Hydrogen Peroxide / metabolism
  • MicroRNAs / genetics
  • MicroRNAs / metabolism
  • Mutation / genetics
  • Necrosis
  • Plant Diseases / microbiology*
  • Salt Stress
  • Stress, Physiological

Substances

  • AT5G12380 protein, Arabidopsis
  • Annexins
  • Arabidopsis Proteins
  • MicroRNAs
  • RPW8.1 protein, Arabidopsis
  • Hydrogen Peroxide