klavier (klv), A novel hypernodulation mutant of Lotus japonicus affected in vascular tissue organization and floral induction

Authors

  • Erika Oka-Kira,

    1. Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan,
    2. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0112, Japan,
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    • These two authors contributed equally to this work.

  • Kumiko Tateno,

    1. Institute for Biomolecular Science, Faculty of Science, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588, Japan,
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    • These two authors contributed equally to this work.

  • Kin-ichiro Miura,

    1. Institute for Biomolecular Science, Faculty of Science, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588, Japan,
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  • Tatsuya Haga,

    1. Institute for Biomolecular Science, Faculty of Science, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588, Japan,
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  • Masaki Hayashi,

    1. Faculty of Horticulture, Chiba University, Matsudo 648, Matsudo, Chiba 271-8510, Japan,
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  • Kyuya Harada,

    1. Faculty of Horticulture, Chiba University, Matsudo 648, Matsudo, Chiba 271-8510, Japan,
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  • Shusei Sato,

    1. Kazusa DNA Research Institute, Kazusa-kamatari 2-6-7, Kisarazu, Chiba 292-0818, Japan,
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  • Satoshi Tabata,

    1. Kazusa DNA Research Institute, Kazusa-kamatari 2-6-7, Kisarazu, Chiba 292-0818, Japan,
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  • Naoya Shikazono,

    1. Department of Radiation Research for Environment and Resources, JAERI, Watanuki 1233, Takasaki, Gunma 370-1292, Japan, and
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  • Atsushi Tanaka,

    1. Department of Radiation Research for Environment and Resources, JAERI, Watanuki 1233, Takasaki, Gunma 370-1292, Japan, and
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  • Yuichiro Watanabe,

    1. Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
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  • Izumi Fukuhara,

    1. Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan,
    2. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0112, Japan,
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  • Toshiyuki Nagata,

    1. Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan,
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  • Masayoshi Kawaguchi

    Corresponding author
    1. Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan,
    2. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0112, Japan,
      (fax +81 3 5841 4458; e-mail masayosi@biol.s.u-tokyo.ac.jp).
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(fax +81 3 5841 4458; e-mail masayosi@biol.s.u-tokyo.ac.jp).

Summary

A novel hypernodulation mutant line was isolated from Lotus japonicus Miyakojima MG-20 by irradiation with a helium ion beam. This mutant, named klavier (klv), had roots that were densely covered with small nodules. The nodulation zone of klv was significantly wider than that of the wild type. Grafting experiments showed that klv is impaired in the long-distance shoot-to-root autoregulatory mechanism. Thus the shoot genotype was found to be responsible for the negative regulation of nodule development by KLV. Nodulation of klv showed a higher tolerance to nitrogen (KNO3) than the wild type, which is a common feature of hypernodulating mutants. In addition to an increased number of nodules, the klv mutant showed convex leaf veins on the adaxial leaf surface, markedly delayed flowering and dwarf phenotypes. Microscopic examination of the leaf veins revealed that they were discontinuous. Other phenotypes such as fasciated stems, increased number of flowers and bifurcated pistils were also frequently observed in the klv mutant. Among these phenotypes, hypernodulation, aberrant leaf vein formation and significantly delayed flowering were all linked in a monogenic and recessive manner, indicating that these phenotypes are caused by either a single mutation, or tightly linked mutations. KLV was mapped within 0.29 cM on the long arm of chromosome 1.

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