title: Two coordinately regulated homologs of FLOWERING LOCUS T are involved in the control of photoperiodic flowering in soybean.
abstract: FLOWERING LOCUS T (FT) is a key flowering integrator in Arabidopsis (Arabidopsis thaliana), with homologs that encode florigens in many plant species regardless of the type of photoperiodic response. We identified 10 FT homologs, which were arranged as five pairs of linked genes in different homoeologous chromosomal regions, in soybean (Glycine max), a paleopolyploid species. Two of the FT homologs, GmFT2a and GmFT5a, were highly up-regulated under short-day (SD) conditions (inductive for flowering in soybean) and had diurnal expression patterns with the highest expression 4 h after dawn. Under long-day (LD) conditions, expression of GmFT2a and GmFT5a was down-regulated and did not follow a diurnal pattern. Flowering took much longer to initiate under LD than under SD, and only the GmFT5a transcript accumulated late in development under LD. Ectopic expression analysis in Arabidopsis confirmed that both GmFT2a and GmFT5a had the same function as Arabidopsis FT, but the effect of GmFT5a was more prominent. A double-mutant soybean line for two PHYTOCHROME A (PHYA) genes expressed high levels of GmFT2a and GmFT5a under LD, and it flowered slightly earlier under LD than the wild type grown under SD. The expression levels of GmFT2a and GmFT5a were regulated by the PHYA-mediated photoperiodic regulation system, and the GmFT5a expression was also regulated by a photoperiod-independent system in LD. Taken together, our results suggest that GmFT2a and GmFT5a coordinately control flowering and enable the adaptation of soybean to a wide range of photoperiodic environments.
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China.
authors.forename: Fanjiang
authors.initials: F
authors.lastname: Kong
authors.forename: Baohui
authors.initials: B
authors.lastname: Liu
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Xia
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Bo Min
authors.initials: BM
authors.lastname: Kim
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamada
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Akira
authors.initials: A
authors.lastname: Kanazawa
authors.forename: Kyuya
authors.initials: K
authors.lastname: Harada
authors.forename: Jun
authors.initials: J
authors.lastname: Abe
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D002874:Chromosome Mapping; D018744:DNA, Plant / Q000235:genetics; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins