title: FE, a phloem-specific Myb-related protein, promotes flowering through transcriptional activation of FLOWERING LOCUS T and FLOWERING LOCUS T INTERACTING PROTEIN 1.
abstract: In many flowering plants, the transition to flowering is primarily affected by seasonal changes in day length (photoperiod). An inductive photoperiod promotes flowering via synthesis of a floral stimulus, called florigen. In Arabidopsis thaliana, the FLOWERING LOCUS T (FT) protein is an essential component of florigen, which is synthesized in leaf phloem companion cells and is transported through phloem tissue to the shoot apical meristem where floral morphogenesis is initiated. However, the molecular mechanism involved in the long-distance transport of FT protein remains elusive. In this study, we characterized the classic Arabidopsis mutant fe, which is involved in the photoperiodic induction of flowering, and showed that FE encodes a phloem-specific Myb-related protein that was previously reported as ALTERED PHLOEM DEVELOPMENT. Phenotypic analyses of the fe mutant showed that FT expression is reduced in leaf phloem companion cells. In addition, the transport of FT protein from leaves to the shoot apex is impaired in the fe mutant. Expression analyses further demonstrated that FE is also required for transcriptional activation of FLOWERING LOCUS T INTERACTING PROTEIN 1 (FTIP1), an essential regulator for selective trafficking of the FT protein from companion cells to sieve elements. These findings indicate that FE plays a dual role in the photoperiodic induction of flowering: as a transcriptional activator of FT on the one hand, and its transport machinery component, FTIP1, on the other hand. Thus, FE is likely to play a role in regulating FT by coordinating FT synthesis and FT transport in phloem companion cells.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Mitsutomo
authors.initials: M
authors.lastname: Abe
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Kaya
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Watanabe-Taneda
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Mio
authors.initials: M
authors.lastname: Shibuta
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.|Graduate School of Biostudies, Kyoto University, Yoshida Konoecho, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Yamaguchi
authors.affiliation: Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kurata
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, 28049, Spain.
authors.forename: Israel
authors.initials: I
authors.lastname: Ausín
authors.affiliation: Graduate School of Biostudies, Kyoto University, Yoshida Konoecho, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Araki
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, 28049, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alonso-Blanco
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D052585:Phloem / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified; D021381:Protein Transport; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C000608384:APL protein, Arabidopsis; D029681:Arabidopsis Proteins; C418905:FT protein, Arabidopsis; C574085:FTIP1 protein, Arabidopsis; D008565:Membrane Proteins; D014157:Transcription Factors
keywords: Arabidopsis thaliana; FLOWERING LOCUS T; Myb-related protein; florigen; flowering; long-distance transport