title: Thidiazuron influences the endogenous levels of cytokinins and IAA during the flowering of isolated shoots of Dendrobium.
abstract: This study reports the effects of thidiazuron (TDZ) on the endogenous levels of indoleacetic acid (IAA), zeatin, zeatin riboside ([9R]Z), isopentenyladenine and isopentenyladenosine ([9R]iP) as well as structural changes in the apical meristem of Dendrobium Second Love shoots during flower induction and initial development in vitro. The results revealed that the presence of 1.8microM TDZ had a profound effect on the endogenous cytokinins (CKs) and IAA levels of the explants, when compared to those grown on a TDZ-free medium. A significant increase in CKs (especially [9R]iP and [9R]Z) and IAA in the first samples (taken at day 5) grown on TDZ-enriched medium was associated with flower induction, while a second increase in the level of these hormones after 25d of culture was related to flower development. The histological changes detected in the shoot apical meristem of explants grown in the presence of 1.8microM TDZ during 30d of culture are also described. Based on these findings, it is suggested that both auxin and CKs seem to be involved with the floral transition of Dendrobium Second Love in vitro. However, a possible direct effect of TDZ on flower formation is not discarded.
authors.affiliation: Universidade Federal do Tocantins, Nùcleo de Estudos Ambientais (NEAMB), Caixa Postal 111, 77500-000 Porto Nacional, Tocantins, Brazil. wmelo@uft.edu.br
authors.forename: Wagner
authors.initials: W
authors.lastname: de Melo Ferreira
authors.forename: Gilberto
authors.initials: G
authors.lastname: Barbante Kerbauy
authors.forename: Jane
authors.initials: J
authors.lastname: Elizabeth Kraus
authors.forename: Rosete
authors.initials: R
authors.lastname: Pescador
authors.forename: Rogério
authors.initials: R
authors.lastname: Mamoru Suzuki
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D031667:Dendrobium / Q000502:physiology*; D035264:Flowers / Q000254:growth & development*; D007210:Indoleacetic Acids / Q000378:metabolism*; D007541:Isopentenyladenosine / Q000031:analogs & derivatives / Q000378:metabolism; D010671:Phenylurea Compounds / Q000494:pharmacology*; D018520:Plant Shoots / Q000187:drug effects; D013830:Thiadiazoles / Q000494:pharmacology*; D015026:Zeatin / Q000378:metabolism
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids; D010671:Phenylurea Compounds; D013830:Thiadiazoles; C016785:thidiazuron; C001478:N(6)-(delta(2)-isopentenyl)adenine; C030737:indoleacetic acid; D007541:Isopentenyladenosine; D015026:Zeatin; C009699:zeatin riboside; D000241:Adenosine