Over-expression of the cell death regulator BAX inhibitor-1 in barley confers reduced or enhanced susceptibility to distinct fungal pathogens

Theor Appl Genet. 2009 Feb;118(3):455-63. doi: 10.1007/s00122-008-0912-2. Epub 2008 Oct 28.


BAX inhibitor-1 (BI-1) is a conserved cell death regulator protein that inhibits mammalian BAX-induced cell death in yeast, animals and plants. Additionally, HvBI-1 suppresses defense responses and resistance to the powdery mildew fungus Blumeria graminis f.sp. hordei (Bgh) when over-expressed in single epidermal cells of barley. To test the potential of ectopic expression of BI-1 to influence fungal interactions with crop plants, we produced stable transgenic barley plants expressing a green fluorescing protein (GFP) fusion of HvBI-1 under control of the cauliflower mosaic virus 35S promoter. GFP-HvBI-1 plants were fertile and did not display obvious developmental alterations when compared to wild type parents. GFP-HvBI-1 plants were more resistant to single cell death induced by ballistic delivery of a mammalian proapototic BAX expression construct and more susceptible to biotrophic Bgh. Microscopic observation of the interaction phenotype revealed that enhanced susceptibility, i.e. a higher degree of successful establishment of haustoria in epidermal cells, was associated with a reduced frequency of hypersensitive cell death reactions. In contrast, young seedlings of GFP-HvBI-1 barley were more resistant to Fusarium graminearum than wild type or azygous controls. Hence the effect of GFP-HvBI-1 on the outcome of a particular plant-fungus interaction appeared dependent on the lifestyle of the pathogen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics*
  • Ascomycota / physiology
  • Gene Expression
  • Green Fluorescent Proteins / analysis
  • Hordeum / genetics*
  • Hordeum / microbiology
  • Hordeum / physiology
  • Immunity, Innate / genetics
  • Phenotype
  • Plant Diseases / genetics*
  • Plant Diseases / microbiology
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Proteins / physiology
  • Plants, Genetically Modified / microbiology
  • Recombinant Fusion Proteins / analysis
  • Seedlings / genetics
  • Seedlings / microbiology
  • Seedlings / physiology


  • Plant Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins