An importin alpha homolog, MOS6, plays an important role in plant innate immunity

Curr Biol. 2005 Jun 21;15(12):1129-35. doi: 10.1016/j.cub.2005.05.022.


Plant disease resistance is the consequence of an innate defense mechanism mediated by Resistance (R) genes [1]. The conserved structure of one class of R protein is reminiscent of Toll-like receptors (TLRs) and Nucleotide binding oligomerization domain (NOD) proteins-immune-response perception modules in animal cells [2, 3, and 4]. The Arabidopsis snc1 (suppressor of npr1-1, constitutive, 1) mutant contains a mutation in a TIR-NBS-LRR-type of R gene that renders resistance responses constitutively active without interaction with pathogens [5]. Few components of the downstream signaling network activated by snc1 are known. To search for regulators of R-gene-mediated resistance, we screened for genetic suppressors of snc1. Three alleles of the mutant mos6 (modifier of snc1, 6) partially suppressed constitutive-resistance responses and immunity to virulent pathogens in snc1. Furthermore, the mos6-1 single mutant exhibited enhanced disease susceptibility to a virulent oomycete pathogen. MOS6, identified by positional cloning, encodes importin alpha3, one of eight alpha importins in Arabidopsis [6]. alpha importins mediate the import of specific proteins across the nuclear envelope. We previously reported that MOS3, a protein homologous to human nucleoporin 96, is required for constitutive resistance in snc1 [7]. Our data highlight an essential role for nucleo-cytoplasmic trafficking, especially protein import, in plant innate immunity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / immunology
  • Arabidopsis Proteins / metabolism
  • Genetic Predisposition to Disease
  • Karyopherins / genetics*
  • Karyopherins / immunology
  • Karyopherins / metabolism
  • Molecular Sequence Data
  • Mutation
  • Oomycetes / pathogenicity
  • Plant Diseases / genetics*
  • Plant Diseases / microbiology
  • Plants / genetics*
  • Plants / immunology*
  • Protein Subunits / genetics
  • Pseudomonas syringae / pathogenicity
  • Sequence Homology, Amino Acid
  • Subcellular Fractions
  • Virulence
  • alpha Karyopherins / genetics*


  • Arabidopsis Proteins
  • Karyopherins
  • MOS6 protein, Arabidopsis
  • Protein Subunits
  • SNC1 protein, Arabidopsis
  • alpha Karyopherins

Associated data

  • GENBANK/DQ087970