wheat TaGI1, involved in photoperiodic flowering, encodes an Arabidopsis GI ortholog

• Published in: Plant molecular biology 2005-05, Vol.58 (1), p.53-64
• Main Authors: Zhao, X.Y, Liu, M.S, Li, J.R, Guan, C.M, Zhang, X.S
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Blotting, Northern; Circadian Rhythm; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; epidermis (plant); flowering; flowering date; Flowers - genetics; Flowers - growth & development; Flowers - radiation effects; gene expression; Gene Expression Regulation, Developmental - radiation effects; Gene Expression Regulation, Plant - radiation effects; genes; Genetic Complementation Test; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; In Situ Hybridization; leaves; messenger RNA; Microscopy, Fluorescence; Molecular Sequence Data; Mutation; nucleotide sequences; Onions - cytology; Onions - genetics; Onions - metabolism; phenology; Photoperiod; photoperiodism; Phylogeny; Plant Epidermis - cytology; Plant Epidermis - genetics; Plant Epidermis - metabolism; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - radiation effects; Plant Proteins - genetics; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - radiation effects; Plants, Genetically Modified; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; seedlings; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid; shoots; TaGI1 gene; Transfection; Triticum - genetics; Triticum - growth & development; Triticum - radiation effects; Triticum aestivum; wheat
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-005-4162-2

Wheat (Triticum aestivum L.) is an important crop and requires long day and short night to flower. To study the molecular mechanism of photoperiodic regulation of flowering in this species, we isolated a wheat TaGI1 gene, an ortholog of GIGANTEA (GI) in Arabidopsis. RNA blot hybridization revealed that TaGI1 is expressed in leaves in a rhythmic manner under long day and short day conditions and its rhythmic expression is regulated by photoperiods and circadian clocks. Further study demonstrated that the TaGI1 rhythmic expression in the leaves of seedlings is initiated by photoperiods, implying that TaGI1 does not show circadian regulation until after being entrained in a light/dark cycle. Interestingly, TaGI1 mRNA was detected in adaxial epidermal cells right above the vascular bundles of leaves, suggesting that the localization of TaGI1 transcripts in leaves may function to regulate flowering in response to photoperiods. Since overexpression of TaGI1 altered flowering time in wild type and complemented the gi mutant in Arabidopsis, it confirmed that TaGI1 is an ortholog of GI in Arabidopsis.