title: Cytokinin promotes flowering of Arabidopsis via transcriptional activation of the FT paralogue TSF.
abstract: Cytokinins are involved in many aspects of plant growth and development, and physiological evidence also indicates that they have a role in floral transition. In order to integrate these phytohormones into the current knowledge of genetically defined molecular pathways to flowering, we performed exogenous treatments of adult wild type and mutant Arabidopsis plants, and analysed the expression of candidate genes. We used a hydroponic system that enables synchronous growth and flowering of Arabidopsis, and allows the precise application of chemicals to the roots for defined periods of time. We show that the application of N⁶-benzylaminopurine (BAP) promotes flowering of plants grown in non-inductive short days. The response to cytokinin treatment does not require FLOWERING LOCUS T (FT), but activates its paralogue TWIN SISTER OF FT (TSF), as well as FD, which encodes a partner protein of TSF, and the downstream gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). Treatment of selected mutants confirmed that TSF and SOC1 are necessary for the flowering response to BAP, whereas the activation cascade might partially act independently of FD. These experiments provide a mechanistic basis for the role of cytokinins in flowering, and demonstrate that the redundant genes FT and TSF are differently regulated by distinct floral-inducing signals.
authors.affiliation: Laboratory of Plant Physiology, University of Liège, Bât. B22 Sart Tilman, B-4000 Liège, Belgium.
authors.forename: Maria
authors.initials: M
authors.lastname: D'Aloia
authors.forename: Delphine
authors.initials: D
authors.lastname: Bonhomme
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bouché
authors.forename: Karim
authors.initials: K
authors.lastname: Tamseddak
authors.forename: Sandra
authors.initials: S
authors.lastname: Ormenese
authors.forename: Stefano
authors.initials: S
authors.lastname: Torti
authors.forename: George
authors.initials: G
authors.lastname: Coupland
authors.forename: Claire
authors.initials: C
authors.lastname: Périlleux
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D001593:Benzyl Compounds / Q000494:pharmacology; D003583:Cytokinins / Q000494:pharmacology / Q000502:physiology*; D018744:DNA, Plant / Q000235:genetics; D035264:Flowers / Q000187:drug effects / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000187:drug effects; D026161:MADS Domain Proteins / Q000235:genetics; D009154:Mutation; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics*; D010937:Plant Growth Regulators / Q000494:pharmacology / Q000502:physiology*; D030821:Plants, Genetically Modified; D011687:Purines / Q000494:pharmacology; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D003583:Cytokinins; D018744:DNA, Plant; C503117:FD protein, Arabidopsis; C418905:FT protein, Arabidopsis; D026161:MADS Domain Proteins; D049488:Phosphatidylethanolamine Binding Protein; D010937:Plant Growth Regulators; D011687:Purines; C500577:TSF protein, Arabidopsis; D014157:Transcription Factors; C480551:benzylaminopurine