Mechanism of roots to grow toward gravity

November 25, 2020

A joint research group from RIKEN CSRS, Nara Institute of Science and Technology, Tokyo University of Agriculture and Technology, and Okayama University of Science has discovered a transmembrane transporter that regulates root gravitropism by mediating cellular uptake of indole-3-butyric acid, a minor precursor of the plant hormone auxin.

Plant roots sense gravity and grow into the ground. This phenomenon is induced by the asymmetric distribution of auxin in the gravity side of the root tip. While majority of indole-3-acetic acid (IAA), the major endogenous auxin, is synthesized from indole-3-pyruvic acid, a very small amount of the compound is also synthesized from IBA.

In this study, the research group identified NPF7.3, one of the Arabidopsis transporter family called NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF), as an IBA importer, and showed that IAA synthesized from IBA plays an important role in gravitropism.

This study revealed a part of the mechanisms that regulate root gravitropic responses. Modulation of root architecture by regulating the function of NPF7.3 will contribute to the improvement of water and nutrients uptake from roots and hence to better crop production.

Original article
Proceedings of the National Academy of Sciences of the United States of America doi:10.1073/pnas.2013305117
S. Watanabe, N. Takahashi, Y. Kanno, H. Suzuki, Y. Aoi, N. Takeda-Kamiya, K. Toyooka, H. Kasahara, K. Hayashi, M. Umeda, M. Seo,
"The Arabidopsis NRT1/PTR FAMILY Protein NPF7.3/NRT1.5 is an Indole-3-butyric Acid Transporter Involved in Root Gravitropism".
Mitsunori Seo; Unit Leader
Shunsuke Watanabe; Special Postdoctoral Researcher
Dormancy and Adaptation Research Unit