Journal Article

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

Kang, Joohyun, Lee, Youngsook, Ko, Donghwi, Park, Jiyoung, Kwon, Mi, Sakakibara, Hitoshi, Kim, Kyung Yoon, Martinoia, Enrico, Kiba, Takatoshi, Do, Jihye, Kojima, Mikiko, Song, Won-Yong, Endler, Anne

2014

Overview

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.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: ABC transporters / Arabidopsis / Arabidopsis - genetics / Arabidopsis - growth & development / Arabidopsis - metabolism / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / ATP Binding Cassette Transporter, Sub-Family G / ATP-Binding Cassette Transporters - genetics / ATP-Binding Cassette Transporters - metabolism / Auxins / Biological Sciences / Biosynthesis / cytokinesis / Cytokinins / Cytokinins - biosynthesis / Cytokinins - metabolism / Flowers & plants / Gene Expression Regulation, Plant / Genes / Graftage / growth retardation / Hormones / mutants / Phenotypes / Plant growth / Plant Growth Regulators - metabolism / plant hormones / Plant roots / Plant Roots - growth & development / Plant Roots - metabolism / Plant Shoots - growth & development / Plant Shoots - metabolism / Plants / Roots / Rootstocks / scions / Seedlings / shoots / Signal Transduction - physiology / Translocation / Xylem