title: The mode of action of thidiazuron: auxins, indoleamines, and ion channels in the regeneration of Echinacea purpurea L.
abstract: The biochemical mechanisms underlying thidiazuron (TDZ)-induced regeneration in plant cells have not been clearly elucidated. Exposure of leaf explants of Echinacea purpurea to a medium containing TDZ results in undifferentiated cell proliferation and differentiated growth as mixed shoot organogenesis and somatic embryogenesis. The current studies were undertaken to determine the potential roles of auxin, indoleamines, and ion signaling in the dedifferentiation and redifferentiation of plant cells. E. purpurea leaf explants were found to contain auxin and the related indoleamine neurotransmitters, melatonin, and serotonin. The levels of these endogenous indoleamines were increased by exposure to TDZ associated with the induction of regeneration. The auxin-transport inhibitor 2,3,5-triiodobenzoic acid and auxin action inhibitor, p-chlorophenoxyisobutyric acid decreased the TDZ-induced regeneration but increased concentrations of endogenous serotonin and melatonin. As well, inhibitors of calcium and sodium transport significantly reduced TDZ-induced morphogenesis while increasing endogenous indoleamine content. These data indicate that TDZ-induced regeneration is the manifestation of a metabolic cascade that includes an initial signaling event, accumulation, and transport of endogenous plant signals such as auxin and melatonin, a system of secondary messengers, and a concurrent stress response.
authors.affiliation: Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: Maxwell P A
authors.initials: MP
authors.lastname: Jones
authors.forename: Jin
authors.initials: J
authors.lastname: Cao
authors.forename: Rob
authors.initials: R
authors.lastname: O'Brien
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Murch
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Saxena
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000588:Amines / Q000378:metabolism*; D002995:Clofibric Acid / Q000494:pharmacology; D020900:Echinacea / Q000187:drug effects* / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D008012:Lidocaine / Q000494:pharmacology; D008550:Melatonin / Q000378:metabolism; D010671:Phenylurea Compounds / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D012038:Regeneration / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism; D013830:Thiadiazoles / Q000494:pharmacology*; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D000588:Amines; D007210:Indoleacetic Acids; D007211:Indoles; D007473:Ion Channels; D010671:Phenylurea Compounds; D013830:Thiadiazoles; D014283:Triiodobenzoic Acids; C016785:thidiazuron; D012701:Serotonin; D002995:Clofibric Acid; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D008012:Lidocaine; C052968:2,3,5-triiodobenzoic acid; D008550:Melatonin