New Mechanism of Long-Distance Transport of the Plant Hormone Cytokinin Uncovered

June 12, 2026

Opening the Door to Artificial Control of Growth in Distant Plant Organs

Researchers from Shimane University, in collaboration with Chubu University, RIKEN CSRS, The University of Tokyo, Okayama University, and Nagoya University, have discovered that the cytokinin receptor gene AHK3 regulates the root-to-shoot transport of trans-zeatin-type cytokinins via the xylem.

Trans-zeatin-type cytokinins synthesized in roots are known to be transported through the xylem to leaves, where they promote leaf growth. In this study, the researchers used grafting techniques to generate plants with root-specific AHK3 deficiency in the model plant Arabidopsis thaliana. They found that loss of AHK3 function specifically in roots significantly increased trans-zeatin-type cytokinin levels in both the roots and xylem sap.
As a result, cytokinin responsiveness was enhanced in the leaves, which are distant organs from the roots, leading to a successful artificial increase in leaf blade area.

The findings suggest that applying this approach to grafted crop seedlings may make it possible to improve desirable traits in the scion through genetic modification of the rootstock alone, while preserving the superior characteristics—such as flavor—of the scion cultivar. This could contribute to the development of highly valuable grafted crops with enhanced performance and quality.

 

Original article

Plant and Cell Physiology　doi: 10.1093/pcp/pcag052

K. Monden, T. Suzuki , M. Kojima, Y. Takebayashi, T. Kamiya, T. Kiba, H. Sakakibara, T. Nakagawa, T. Hachiya,

"Cytokinin receptor AHK3 influences leaf size by modulating trans-zeatin-type cytokinin levels in xylem".

Contact

Mikiko Kojima; Technical Scientist
Yumiko Takebayashi; Technical Staff I
Mass Spectrometry and Microscopy Unit