The cAMP signal transduction pathway mediates resistance to dicarboximide and aromatic hydrocarbon fungicides in Ustilago maydis

Fungal Genet Biol. 2001 Apr;32(3):183-93. doi: 10.1006/fgbi.2001.1258.


The cAMP signal transduction pathway mediates the switch between yeast-like and filamentous growth and influences both sexual development and pathogenicity in the smut fungus Ustilago maydis. Signaling via cAMP may also play a role in fungicide resistance in U. maydis. In particular, the adr1 gene, which encodes the catalytic subunit of the U. maydis cAMP-dependent protein kinase (PKA), is implicated in resistance to the dicarboximide and aromatic hydrocarbon fungicides. In this study, we examined the sensitivity of PKA to vinclozolin and could not demonstrate direct inhibition of protein kinase activity. However, we did find that mutants with disruptions in the ubc1 gene, which encodes the regulatory subunit of PKA, were resistant to both vinclozolin and chloroneb. We also found that these fungicides altered the morphology of both wild-type and ubc1 mutant cells. In addition, strains that are defective in ubc1 display osmotic sensitivity, a property often associated with vinclozolin and chloroneb resistance in other fungi.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorobenzenes / pharmacology
  • Cyclic AMP / metabolism*
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Drug Resistance, Microbial
  • Fungicides, Industrial / pharmacology*
  • Gene Expression Regulation, Fungal
  • Hydrocarbons, Aromatic / pharmacology*
  • Imides / pharmacology
  • Oxazoles / pharmacology*
  • Signal Transduction*
  • Ustilago / drug effects*
  • Ustilago / growth & development


  • Chlorobenzenes
  • Fungicides, Industrial
  • Hydrocarbons, Aromatic
  • Imides
  • Oxazoles
  • chloroneb
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • vinclozolin