Letter

Synthetic control of flowering in rice independent of the cultivation environment

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Abstract

For genetically homogeneous crops, the timing of flowering is determined largely by the cultivation environment and is strongly associated with the yield and quality of the harvest1. Flowering time and other agronomical traits are often tightly correlated, which can lead to difficulty excluding the effects of flowering time when evaluating the characteristics of different genetic varieties2. Here, we describe the development of transgenic rice plants whose flowering time can be controlled by specific agrochemicals. We first developed non-flowering rice plants by overexpressing a floral repressor gene, Grain number, plant height and heading date 7 (Ghd7)3,4, to inhibit any environmentally induced spontaneous flowering. We then co-transformed plants with a rice florigen gene, Heading date 3a (Hd3a)5, which is induced by the application of specific agrochemicals. This permitted the flowering time to be experimentally controlled regardless of the cultivation environment: some transgenic plants flowered only after agrochemical treatment. Furthermore, plant size and yield-related traits could, in some cases, be increased owing to both a longer duration of vegetative growth and an increased panicle size. This ability to control flowering time experimentally, independently of environmental variables, may lead to production of crops suitable for growth in different climates and facilitate breeding for various agronomical traits.

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Author information

Author notes

    • Ryo Okada
    • , Yasue Nemoto
    •  & Naokuni Endo-Higashi

    Present addresses: Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan (R.O.); Field Omics Unit, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8602, Japan (Y.N.); Japan Grain Inspection Association, Tyuohu-ku, Tokyo 103-0026, Japan (N.E.-H.).

Affiliations

  1. Functional Plant Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan

    • Ryo Okada
    • , Yasue Nemoto
    • , Naokuni Endo-Higashi
    •  & Takeshi Izawa
  2. Laoratory of Plant Breeding & Genetics, Department of Agriculture, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan

    • Takeshi Izawa

Authors

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Contributions

T.I. conceived and conducted the entire experiments of this work. R.O. performed most of experiments in this work. Y.N. performed the analysis of Ghd7-overexpressing plant in rice. N.E.-H. performed the effect of Hd3a ectopic expression in the Ghd7-overexpressing plant in rice. T.I. and R.O. wrote the manuscript and the others revised it.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Takeshi Izawa.

Supplementary information

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    Supplementary Information

    Supplementary Figures 1–10.

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    Supplementary Tables 1–8.