title: Inhibition of efflux transporter-mediated fungicide resistance in Pyrenophora tritici-repentis by a derivative of 4'-hydroxyflavone and enhancement of fungicide activity.
abstract: Populations of the causal agent of wheat tan spot, Pyrenophora tritici-repentis, that are collected from fields frequently treated with reduced fungicide concentrations have reduced sensitivity to strobilurin fungicides and azole fungicides (C14-demethylase inhibitors). Energy-dependent efflux transporter activity can be induced under field conditions and after in vitro application of sublethal amounts of fungicides. Efflux transporters can mediate cross-resistance to a number of fungicides that belong to different chemical classes and have different modes of action. Resistant isolates can grow on substrata amended with fungicides and can infect plants treated with fungicides at levels above recommended field concentrations. We identified the hydroxyflavone derivative 2-(4-ethoxy-phenyl)-chromen-4-one as a potent inhibitor of energy-dependent fungicide efflux transporters in P. tritici-repentis. Application of this compound in combination with fungicides shifted fungicide-resistant P. tritici-repentis isolates back to normal sensitivity levels and prevented infection of wheat leaves. These results highlight the role of energy-dependent efflux transporters in fungicide resistance and could enable a novel disease management strategy based on the inhibition of fungicide efflux to be developed.
authors.affiliation: Martin Luther University Halle-Wittenberg, Faculty of Agriculture, Phytopathology and Plant Protection, D-06099 Halle (Saale), Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Reimann
authors.forename: Holger B
authors.initials: HB
authors.lastname: Deising
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000179:Acrylates / Q000494:pharmacology; D001203:Ascomycota / Q000187:drug effects*; D025141:Drug Resistance, Fungal / Q000187:drug effects*; D004852:Epoxy Compounds / Q000494:pharmacology; D047309:Flavones / Q000737:chemistry / Q000494:pharmacology*; D005659:Fungicides, Industrial / Q000494:pharmacology*; D015966:Gene Expression Regulation, Fungal; D008689:Methacrylates; D008826:Microbial Sensitivity Tests; D010648:Phenylacetates / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D011743:Pyrimidines / Q000494:pharmacology; D000073739:Strobilurins; D014230:Triazoles / Q000494:pharmacology; D014908:Triticum / Q000382:microbiology*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000179:Acrylates; D004852:Epoxy Compounds; D047309:Flavones; D005659:Fungicides, Industrial; D008689:Methacrylates; D010648:Phenylacetates; D011743:Pyrimidines; D000073739:Strobilurins; D014230:Triazoles; C469328:kresoxim-methyl; C087670:azoxystrobin; C109476:epoxiconazole