title: The Medicago FLOWERING LOCUS T homolog, MtFTa1, is a key regulator of flowering time.
abstract: FLOWERING LOCUS T (FT) genes encode proteins that function as the mobile floral signal, florigen. In this study, we characterized five FT-like genes from the model legume, Medicago (Medicago truncatula). The different FT genes showed distinct patterns of expression and responses to environmental cues. Three of the FT genes (MtFTa1, MtFTb1, and MtFTc) were able to complement the Arabidopsis (Arabidopsis thaliana) ft-1 mutant, suggesting that they are capable of functioning as florigen. MtFTa1 is the only one of the FT genes that is up-regulated by both long days (LDs) and vernalization, conditions that promote Medicago flowering, and transgenic Medicago plants overexpressing the MtFTa1 gene flowered very rapidly. The key role MtFTa1 plays in regulating flowering was demonstrated by the identification of fta1 mutants that flowered significantly later in all conditions examined. fta1 mutants do not respond to vernalization but are still responsive to LDs, indicating that the induction of flowering by prolonged cold acts solely through MtFTa1, whereas photoperiodic induction of flowering involves other genes, possibly MtFTb1, which is only expressed in leaves under LD conditions and therefore might contribute to the photoperiodic regulation of flowering. The role of the MtFTc gene is unclear, as the ftc mutants did not have any obvious flowering-time or other phenotypes. Overall, this work reveals the diversity of the regulation and function of the Medicago FT family.
authors.affiliation: Department of Biochemistry, University of Otago, Dunedin 9054, New Zealand.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Laurie
authors.forename: Payal
authors.initials: P
authors.lastname: Diwadkar
authors.forename: Mauren
authors.initials: M
authors.lastname: Jaudal
authors.forename: Lulu
authors.initials: L
authors.lastname: Zhang
authors.forename: Valérie
authors.initials: V
authors.lastname: Hecht
authors.forename: Jiangqi
authors.initials: J
authors.lastname: Wen
authors.forename: Million
authors.initials: M
authors.lastname: Tadege
authors.forename: Kirankumar S
authors.initials: KS
authors.lastname: Mysore
authors.forename: Joanna
authors.initials: J
authors.lastname: Putterill
authors.forename: James L
authors.initials: JL
authors.lastname: Weller
authors.forename: Richard C
authors.initials: RC
authors.lastname: Macknight
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D003080:Cold Temperature; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D029902:Medicago / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018519:Meristem / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D017440:Photoperiod; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015854:Up-Regulation / Q000235:genetics
chemical_list: D010940:Plant Proteins