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Proc Natl Acad Sci U S A. 2014 May 13;111(19):7150-5. doi: 10.1073/pnas.1321519111. Epub 2014 Apr 28.

Arabidopsis ABCG14 is essential for the root-to-shoot translocation of cytokinin.

Author information

1
Pohang University of Science and Technology-Universität Zürich (POSTECH-UZH) Global Research Laboratory, Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea;
2
Plant Productivity Systems Research Group, RIKEN Center for Sustainable Resource Science, Suehiro 1-7-22, Tsurumi, Yokohama 230-0045, Japan;
3
Department of Biotechnology, College of Life Science and Biotechnology, Korea University, Seoul 136-713, Korea; and.
4
Institut für Pflanzenbiologie, Universität Zürich, 8008 Zürich, Switzerland.
5
Pohang University of Science and Technology-Universität Zürich (POSTECH-UZH) Global Research Laboratory, Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea;Institut für Pflanzenbiologie, Universität Zürich, 8008 Zürich, Switzerland.
6
Pohang University of Science and Technology-Universität Zürich (POSTECH-UZH) Global Research Laboratory, Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea; ylee@postech.ac.kr.

Abstract

Cytokinins are phytohormones that induce cytokinesis and are essential for diverse developmental and physiological processes in plants. Cytokinins of the trans-zeatin type are mainly synthesized in root vasculature and transported to the shoot, where they regulate shoot growth. However, the mechanism of long-distance transport of cytokinin was hitherto unknown. Here, we report that the Arabidopsis ATP-binding cassette (ABC) transporter subfamily G14 (AtABCG14) is mainly expressed in roots and plays a major role in delivering cytokinins to the shoot. Loss of AtABCG14 expression resulted in severe shoot growth retardation, which was rescued by exogenous trans-zeatin application. Cytokinin content was decreased in the shoots of atabcg14 plants and increased in the roots, with consistent changes in the expression of cytokinin-responsive genes. Grafting of atabcg14 scions onto wild-type rootstocks restored shoot growth, whereas wild-type scions grafted onto atabcg14 rootstocks exhibited shoot growth retardation similar to that of atabcg14. Cytokinin concentrations in the xylem are reduced by ∼90% in the atabcg14 mutant. These results indicate that AtABCG14 is crucial for the translocation of cytokinin to the shoot. Our results provide molecular evidence for the long-distance transport of cytokinin and show that this transport is necessary for normal shoot development.

KEYWORDS:

ABC transporter; long-distance signal; tZ-type cytokinin translocation

PMID:
24778257
PMCID:
PMC4024864
DOI:
10.1073/pnas.1321519111
[Indexed for MEDLINE]
Free PMC Article
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