title: Dicarboximide resistance in field isolates of Alternaria alternata is mediated by a mutation in a two-component histidine kinase gene.
abstract: Isolates of Alternaria alternata collected from a field site which had previously been treated with the dicarboximide fungicide iprodione were found to demonstrate a high level of resistance to iprodione and the phenylpyrrole fungicide, fludioxonil in plate assays. In order to determine the genetic basis for this fungicide resistance a partial length clone of a two-component histidine kinase (HK) was isolated from genomic DNA of a fungicide-sensitive A. alternata isolate using degenerate primers by PCR. Analysis of the AaHK1 gene structure indicates the presence of six 90 amino acid repeat domains upstream of a kinase domain as found in the homologous HK genes from other fungal species. Comparison of nucleic acid sequences from the fungicide-sensitive and fungicide-resistant A. alternata isolates confirmed the presence of mutations leading to premature termination of the translated HK protein. The possible role of the two-component HK in the development of dicarboximide resistance in A. alternata is discussed.
authors.affiliation: CSIRO Plant Industry, Horticulture Unit, Glen Osmond, SA 5064, Australia. ian.dry@csiro.au
authors.forename: Ian B
authors.initials: IB
authors.lastname: Dry
authors.forename: Khor H
authors.initials: KH
authors.lastname: Yuan
authors.forename: Don G
authors.initials: DG
authors.lastname: Hutton
mesh_terms: D000528:Alternaria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D000595:Amino Acid Sequence; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D004271:DNA, Fungal; D004149:Dioxoles / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005659:Fungicides, Industrial / Q000494:pharmacology*; D000071677:Histidine Kinase; D006827:Hydantoins; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology; D011494:Protein Kinases / Q000235:genetics* / Q000502:physiology; D011758:Pyrroles / Q000494:pharmacology
chemical_list: D004271:DNA, Fungal; D004149:Dioxoles; D005659:Fungicides, Industrial; D006827:Hydantoins; D011758:Pyrroles; D000620:Aminoimidazole Carboxamide; D011494:Protein Kinases; D000071677:Histidine Kinase; C108339:fludioxonil; C033148:iprodione