Rice Indeterminate 1 (OsId1) is necessary for the expression of Ehd1 (Early heading date 1) regardless of photoperiod

Authors

  • Soon Ju Park,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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  • Song Lim Kim,

    1. Department of Life Science and Functional Genomic Center, Pohang University of Science and Technology, Pohang 790-784, Korea
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  • Shinyoung Lee,

    1. Department of Life Science and Functional Genomic Center, Pohang University of Science and Technology, Pohang 790-784, Korea
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  • Byoung Il Je,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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  • Hai Long Piao,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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  • Sung Han Park,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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    • Present address: Rice Functional Genomics, National Institute of Agricultural Biotechnology, RDA, Suwon, 441-707, South Korea.

  • Chul Min Kim,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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    • Present address: Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.

  • Choong-Hwan Ryu,

    1. Department of Life Science and Functional Genomic Center, Pohang University of Science and Technology, Pohang 790-784, Korea
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  • Su Hyun Park,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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  • Yuan-hu Xuan,

    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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  • Joseph Colasanti,

    1. Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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  • Gynheung An,

    1. Department of Life Science and Functional Genomic Center, Pohang University of Science and Technology, Pohang 790-784, Korea
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  • Chang-deok Han

    Corresponding author
    1. Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Environmental Biotechnology National Core Research Center, Gyeongsang National University, Jinju 660-701, Korea
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*(fax +82 55 759 9363; e-mail cdhan@gsnu.ac.kr).

Summary

Indeterminate 1 (Id1), a classical flowering gene first reported in 1946, is one of the earliest genes whose expression in leaf tissues affects the floral transition in the shoot meristem. How Id1 is integrated into the flowering process is largely unknown. In this study, we examined the genetic action of the rice (Oryza sativa) ortholog OsId1. In rice, OsId1 is preferentially expressed in young leaves, but the overall expression pattern is broader than that in maize (Zea mays). OsId1 is able to activate transcription in yeast. RNAi mutants show a delay in flowering under both short-day (SD) and long-day (LD) conditions. OsId1 regulates the expression of Ehd1 (Early heading date 1) and its downstream genes, including Hd3a (a rice ortholog of FT) and RFT1 (Rice Flowering Locus T1), under both SD and LD conditions. In rice, the expression of Ehd1 is also controlled by the photoperiodic flowering genes OsGI (a rice ortholog of GI) and OsMADS51. However, the expression of OsId1 is independent of OsGI, OsMADS51, and OsMADS50 (a rice SOC1 ortholog). This study demonstrates that the activation of Ehd1 by OsId1 is required for the promotion of flowering.

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