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Systemic transport of trans-zeatin and its precursor have differing roles in Arabidopsis shoots

Nature Plants volume 3, Article number: 17112 (2017) | Download Citation


Organ-to-organ signal transmission is essential for higher organisms to ensure coordinated biological reactions during metabolism and morphogenesis. Similar to organs in animals, plant organs communicate by various signalling molecules. Among them, cytokinins, a class of phytohormones, play a key role as root-to-shoot long-distance signals, regulating various growth and developmental processes in shoots1,2. Previous studies have proposed that trans-zeatin-riboside, a type of cytokinin precursor, is a major long-distance signalling form in xylem vessels and its action depends on metabolic conversion via the LONELY GUY enzyme in proximity to the site of action3,​4,​5. Here we report an additional long-distance signalling form of cytokinin: trans-zeatin, an active form. Grafting between various cytokinin biosynthetic and transportation mutants revealed that root-to-shoot translocation of trans-zeatin, a minor component of xylem cytokinin, controls leaf size but not meristem activity-related traits, whereas that of trans-zeatin riboside is sufficient for regulating both traits. Considering the ratio of trans-zeatin to trans-zeatin-riboside in xylem and their delivery rate change in response to environmental conditions, this dual long-distance cytokinin signalling system allows plants to fine-tune the manner of shoot growth to adapt to fluctuating environments.

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We thank N. Ifuku (RIKEN) for support with all of the experiments A.O. performed. We also thank T. Notaguchi (Nagoya University) for instruction on the grafting technique. This work was supported by the Grant-in-Aid for Young Scientists (B; no. JP16K18566), the Grant-in-Aid for Scientific Research on Innovative Areas (no. JP16H01477 and JP17H06473) and the NC-CARP project from the Ministry of Education, Culture, Sports, Science and Technology and JST CREST (no. JPMJCR13B1), Japan.

Author information


  1. RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan

    • Asami Osugi
    • , Mikiko Kojima
    • , Yumiko Takebayashi
    • , Nanae Ueda
    • , Takatoshi Kiba
    •  & Hitoshi Sakakibara
  2. Department of Biological Mechanisms and Functions, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan

    • Asami Osugi
    •  & Hitoshi Sakakibara


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A.O. conceived the study. A.O., T.K. and H.S. designed the experiments. A.O., M.K., Y.T., N.U. and T.K. performed the experiments. A.O., T.K. and H.S. discussed the results and wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Hitoshi Sakakibara.

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