title: GmFT2a, a soybean homolog of FLOWERING LOCUS T, is involved in flowering transition and maintenance.
abstract: BACKGROUND
  Flowering reversion can be induced in soybean (Glycine max L. Merr.), a typical short-day (SD) dicot, by switching from SD to long-day (LD) photoperiods. This process may involve florigen, putatively encoded by FLOWERING LOCUS T (FT) in Arabidopsis thaliana. However, little is known about the potential function of soybean FT homologs in flowering reversion.
  
  
  METHODS
  A photoperiod-responsive FT homologue GmFT (renamed as GmFT2a hereafter) was cloned from the photoperiod-sensitive cultivar Zigongdongdou. GmFT2a gene expression under different photoperiods was analyzed by real-time quantitative PCR. In situ hybridization showed direct evidence for its expression during flowering-related processes. GmFT2a was shown to promote flowering using transgenic studies in Arabidopsis and soybean. The effects of photoperiod and temperature on GmFT2a expression were also analyzed in two cultivars with different photoperiod-sensitivities.
  
  
  RESULTS
  GmFT2a expression is regulated by photoperiod. Analyses of GmFT2a transcripts revealed a strong correlation between GmFT2a expression and flowering maintenance. GmFT2a transcripts were observed continuously within the vascular tissue up to the shoot apex during flowering. By contrast, transcripts decreased to undetectable levels during flowering reversion. In grafting experiments, the early-flowering, photoperiod-insensitive stock Heihe27 promotes the appearance of GmFT2a transcripts in the shoot apex of scion Zigongdongdou under noninductive LD conditions. The photothermal effects of GmFT2a expression diversity in cultivars with different photoperiod-sensitivities and a hypothesis is proposed.
  
  
  CONCLUSIONS
  GmFT2a expression is associated with flowering induction and maintenance. Therefore, GmFT2a is a potential target gene for soybean breeding, with the aim of increasing geographic adaptation of this crop.
authors.affiliation: The National Key Facility for Crop Gene Resources and Genetic Improvement and MOA Key Lab of Soybean Biology (Beijing), Institute of Crop Science, The Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Sun
authors.forename: Zhen
authors.initials: Z
authors.lastname: Jia
authors.forename: Dong
authors.initials: D
authors.lastname: Cao
authors.forename: Bingjun
authors.initials: B
authors.lastname: Jiang
authors.forename: Cunxiang
authors.initials: C
authors.lastname: Wu
authors.forename: Wensheng
authors.initials: W
authors.lastname: Hou
authors.forename: Yike
authors.initials: Y
authors.lastname: Liu
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Fei
authors.forename: Dazhong
authors.initials: D
authors.lastname: Zhao
authors.forename: Tianfu
authors.initials: T
authors.lastname: Han
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry*; D002940:Circadian Rhythm / Q000235:genetics; D003001:Cloning, Molecular; D019295:Computational Biology; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008969:Molecular Sequence Data; D017440:Photoperiod; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000235:genetics; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000235:genetics / Q000502:physiology*; D013696:Temperature
chemical_list: D029681:Arabidopsis Proteins; C418905:FT protein, Arabidopsis; D010940:Plant Proteins; D012333:RNA, Messenger