Discovery of the mechanism of growth hormone “pooling” in Oryza sativa

March 17, 2026

Determining a metabolic regulatory pathway and contributing to the breeding of crops resistant to environmental changes

In a collaborative study with the RIKEN CSRS, National Agriculture and Food Research Organization, Okayama University of Science, and National Institute of Genetics, Nagoya University discovered a new metabolic regulatory pathway of auxin, a plant hormone in Oryza sativa.

Auxin, a hormone regulating plant growth and development, is also deeply involved in crop yield, including the growth of a root system and panicles. In this study, the research team identified a new metabolic mechanism of auxin “pooling” in rice (Oryza sativa). In general, auxin–amino acid conjugates are irreversibly inactivated by oxidation. However, the enzyme identified in this study, IAAspGT, catalyzes the N-glucosylation of auxin–amino acid conjugates, diverting them from irreversible oxidation and establishing a secondary regulatory pool. The research team also revealed that the activity of this enzyme differs markedly between japonica-type and indica-type cultivars, affecting root system development and assimilate allocation to the panicles. The mechanism for adaptively regulating growth in response to environmental changes is expected to contribute to the development of crops with high nutrient use efficiency and resilience to environmental stress.

 

Original article

Proceedings of the National Academy of Sciences of the United States of America
doi: 10.1073/pnas.2527570123

A. Zenji, K. Hata, S. Segami, N. Makita, M. Kojima, M. Yoshino-Kida, K. Nagai, M. Ashikari, K. Matsubara, M. Yano, S. Fukuoka, K. Hayashi, Y. Sato, T. Hobo, Y. Inukai, H. Sakakibara,

"N-glucosylation of indole-3-acetyl amino acids modulates auxin metabolism and growth traits in Oryza sativa".

Contact

Mikiko Kojima
Technical Scientist
Mass Spectrometry and Microscopy Unit