ZHANG, K., NOVÁK, Ondřej, WEI, Z., GOU, M., ZHANG, X., YU, Y., YANG, H., CAI, Y., STRNAD, Miroslav, LIU, Ch.-J. Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins. Nature Communications. 2014, 5(FEB 2014). ISSN 2041-1723. E-ISSN 2041-1723

Cytokinins are a major group of phytohormones regulating plant growth, development and stress responses. However, in contrast to the well-defined polar transport of auxins, the molecular basis of cytokinin transport is poorly understood. Here we show that an ATP-binding cassette transporter in Arabidopsis, AtABCG14, is essential for the acropetal (root to shoot) translocation of the root-synthesized cytokinins. AtABCG14 is expressed primarily in the pericycle and stelar cells of roots. Knocking out AtABCG14 strongly impairs the translocation of trans-zeatin (tZ)-type cytokinins from roots to shoots, thereby affecting the plant's growth and development. AtABCG14 localizes to the plasma membrane of transformed cells. In planta feeding of C-14 or C-13-labelled tZ suggests that it acts as an efflux pump and its presence in the cells directly correlates with the transport of the fed cytokinin. Therefore, AtABCG14 is a transporter likely involved in the long-distance translocation of cytokinins in planta.