title: Cytochrome P450 Inhibitors Reduce Creeping Bentgrass (Agrostis stolonifera) Tolerance to Topramezone.
abstract: Creeping bentgrass (Agrostis stolonifera L.) is moderately tolerant to the p-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide topramezone. However, the contribution of plant metabolism of topramezone to this tolerance is unknown. Experiments were conducted to determine if known cytochrome P450 monooxygenase inhibitors 1-aminobenzotriazole (ABT) and malathion alone or in combination with the herbicide safener cloquintocet-mexyl influence creeping bentgrass tolerance to topramezone. Creeping bentgrass in hydroponic culture was treated with ABT (70 μM), malathion (70 μm and 1000 g ha(-1)), or cloquintocet-mexyl (70 μM and 1000 g ha(-1)) prior to topramezone (8 g ha(-1)) application. Topramezone-induced injury to creeping bentgrass increased from 22% when applied alone to 79 and 41% when applied with malathion or ABT, respectively. Cloquintocet-mexyl (70 μM and 1000 g ha(-1)) reduced topramezone injury to 1% and increased creeping bentgrass biomass and PSII quantum yield. Cloquintocet-mexyl mitigated the synergistic effects of ABT more than those of malathion. The effects of malathion on topramezone injury were supported by creeping bentgrass biomass responses. Responses to ABT and malathion suggest that creeping bentgrass tolerance to topramezone is influenced by cytochrome P450-catalyzed metabolism. Future research should elucidate primary topramezone metabolites and determine the contribution of cytochrome P450 monooxygenases and glutathione S-transferases to metabolite formation in safened and non-safened creeping bentgrass.
authors.affiliation: Department of Soil and Crop Sciences, Texas A&M AgriLife Extension Service, Dallas, Texas, United States of America.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Elmore
authors.affiliation: Department of Plant Sciences, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: James T
authors.initials: JT
authors.lastname: Brosnan
authors.affiliation: Department of Plant Sciences, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Armel
authors.affiliation: Department of Plant Sciences, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: Dean A
authors.initials: DA
authors.lastname: Kopsell
authors.affiliation: Department of Chemistry, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Best
authors.affiliation: Department of Plant Sciences, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Mueller
authors.affiliation: Department of Plant Sciences, The University of Tennessee, Knoxville, Tennessee, United States of America.
authors.forename: John C
authors.initials: JC
authors.lastname: Sorochan
mesh_terms: D000222:Adaptation, Physiological; D031703:Agrostis / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D018533:Biomass; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004347:Drug Interactions; D006540:Herbicides / Q000494:pharmacology*; D008294:Malathion / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D006540:Herbicides; D011720:Pyrazoles; D011804:Quinolines; D014230:Triazoles; C033020:1-aminobenzotriazole; D003577:Cytochrome P-450 Enzyme System; C514515:cloquintocet-mexyl; D008294:Malathion; C521377:topramezone