Isolation and characterization of Neurospora crassa mutants resistant to antifungal plant defensins

Fungal Genet Biol. 2003 Nov;40(2):176-85. doi: 10.1016/s1087-1845(03)00085-9.

Abstract

Twenty-five Neurospora crassa mutants obtained by chemical mutagenesis were screened for increased resistance to various antifungal plant defensins. Plant defensin-resistant N. crassa mutants were further tested for their cross-resistance towards other families of structurally different antimicrobial peptides. Two N. crassa mutants, termed MUT16 and MUT24, displaying resistance towards all plant defensins tested but not to structurally different antimicrobial peptides were selected for further characterization. MUT16 and MUT24 were more resistant towards plant defensin-induced membrane permeabilization as compared to the N. crassa wild-type. Based on the previously demonstrated key role of fungal sphingolipids in the mechanism of growth inhibition by plant defensins, membrane sphingolipids of MUT16 and MUT24 were analysed. Membranes of these mutants contained structurally different glucosylceramides, novel glycosylinositolphosphorylceramides, and an altered level of steryl glucosides. Evidence is provided to link these clear differences in sphingolipid profiles of N. crassa mutants with their resistance towards different plant defensins.

MeSH terms

  • Anti-Infective Agents / pharmacology
  • Cell Membrane / chemistry
  • Cell Membrane Permeability / drug effects
  • Cell Membrane Permeability / genetics
  • Defensins / pharmacology*
  • Drug Resistance, Fungal / genetics*
  • Ethyl Methanesulfonate / pharmacology
  • Fluorescent Dyes / metabolism
  • Mutagens / pharmacology
  • Mutation
  • Neurospora crassa / drug effects*
  • Neurospora crassa / genetics*
  • Neurospora crassa / growth & development
  • Neurospora crassa / metabolism
  • Organic Chemicals
  • Plant Proteins / pharmacology*
  • Sphingolipids / analysis

Substances

  • Anti-Infective Agents
  • Defensins
  • Fluorescent Dyes
  • Mutagens
  • Organic Chemicals
  • Plant Proteins
  • SYTOX Green
  • Sphingolipids
  • Ethyl Methanesulfonate