title: CsTFL1, a constitutive local repressor of flowering, modulates floral initiation by antagonising florigen complex activity in chrysanthemum.
abstract: Chrysanthemums require repeated cycles of short-day (SD) photoperiod for successful anthesis, but their vegetative state is strictly maintained under long-day (LD) or night-break (NB) conditions. We have previously demonstrated that photoperiodic flowering of a wild diploid chrysanthemum (Chrysanthemum seticuspe f. boreale) is controlled by a pair of systemic floral regulators, florigen (CsFTL3) and anti-florigen (CsAFT), produced in the leaves. Here, we report the functional characterisation of a local floral regulator, CsTFL1, a chrysanthemum orthologue of TERMINAL FLOWER 1 gene in Arabidopsis. Constitutive expression of CsTFL1 in C. seticuspe (CsTFL1-ox) resulted in extremely late flowering under SD and prevented up-regulation of floral meristem identity genes in shoot tips and leaves. Bimolecular fluorescence complementation assay showed that both CsTFL1 and CsFTL3 interacted with CsFDL1, a bZIP transcription factor FD homologue, in the nucleus. The transient gene expression assay indicated that CsTFL1 suppresses flowering by directly antagonising the flower inductive activity of the CsFTL3-CsFDL1 complex. Our results suggest that strict maintenance of vegetative state under non-inductive photoperiod is achieved by the coordinated action of both the systemic floral inhibitor and local floral inhibitor CsTFL1, which is constitutively expressed in shoot tips.
authors.affiliation: NARO Institute of Floricultural Science (NIFS), National Agriculture and Food Research Organization (NARO), 2-1 Fujimoto, Tsukuba, Ibaraki 305-8519, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Higuchi
authors.affiliation: NARO Institute of Floricultural Science (NIFS), National Agriculture and Food Research Organization (NARO), 2-1 Fujimoto, Tsukuba, Ibaraki 305-8519, Japan. Electronic address: tamotsu@affrc.go.jp.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Hisamatsu
mesh_terms: D031202:Chrysanthemum / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D060405:Florigen / Q000037:antagonists & inhibitors*; D035264:Flowers / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008027:Light; D018519:Meristem / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D017440:Photoperiod; D010937:Plant Growth Regulators / Q000037:antagonists & inhibitors*; D018515:Plant Leaves / Q000235:genetics / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D030821:Plants, Genetically Modified; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D060405:Florigen; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012097:Repressor Proteins
keywords: Antiflorigen; Chrysanthemum; Florigen; Flowering