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研究成果

First Identification of Nitrification-Inhibiting Compounds Secreted by Finger Millet
—Discovery of Novel BNI Natural Compounds Produced by Millet Grown Under Low-Nitrogen Conditions—

press202602.pdf1.22 MB

2026-05-08

Japan International Research Center for Agricultural Sciences (JIRCAS)
National Agriculture and Food Research Organization (NARO)
TEKMOF Co., Ltd.
Institute of Science Tokyo

Key Points

  • Two novel compounds with strong biological nitrification inhibition (BNI) activity were identified for the first time in the world from the roots of finger millet grown under low-nitrogen conditions.
  • These compounds are diterpenoids with previously unknown carbon skeletons, distinct from known natural products, and were named coracanols A and B.
  • Using coracanols as indicators, high-BNI lines can be selected, offering potential for low-nitrogen, low-environmental-impact millet production.

Overview

JIRCAS, in collaboration with NARO, the Institute of Science Tokyo, and TEKMOF Co., Ltd. (a university-recognized venture), has for the first time identified biological nitrification inhibition (BNI)1 substances secreted from the roots of finger millet and elucidated their chemical structures. Finger millet is an important crop in semi-arid regions of Sub-Saharan Africa and South Asia due to its strong tolerance to harsh environmental conditions and high nutritional value, with its importance expected to grow further as climate change progresses. Nitrification suppression in agricultural soils is a key mechanism for improving nitrogen-use efficiency. However, the actual substances responsible for BNI in finger millet had not been identified until now.

 

The research group isolated two compounds with strong BNI activity from root exudates of finger millet grown under low-nitrogen conditions. Detailed structural analysis revealed that both are naturally occurring2 diterpenoids3 with novel carbon skeletons distinct from known compounds. It was confirmed that these compounds, named coracanols A and B, not only strongly inhibit the activity and growth of soil microorganisms involved in nitrification4 but also accumulate in the leaves, with their levels increasing toward the heading stage.

This finding is expected to promote the development of low-input, environmentally friendly millet production technologies that suppress nitrification—thereby reducing greenhouse gas emissions and water pollution—while decreasing dependence on nitrogen fertilizers. Furthermore, as natural substances with novel carbon skeletons, coracanols are anticipated to have applications not only in agriculture but also in the fields of natural product chemistry and life sciences, including potential uses in functional foods and pharmaceutical materials.

The results of this study were published as open access in the online edition of the international scientific journal Organic Letters on March 9 (Japan time).

Related Information

Funding
This research was conducted under the Strategic International Collaborative Research Promotion Commissioned Project (Joint Research Field with the Republic of India), with results derived from the research project entitled "Development of planet-friendly agricultural production system using biological nitrification inhibition (BNI) technology."
Patent
Application in progress

Publication Details

Authors
J. Otaka, G.V. Subbarao, S. Matsumiya, N. Wada, Y. Wada, M. Kawano, K. Kutsuwada, H. Ono, and T. Yoshihashi
Title
Discovery of Coracanols A and B, Two Biological Nitrification Inhibition Diterpenoids from Finger Millet
Journal
Organic Letters
DOI: https://doi.org/10.1021/acs.orglett.6c00300

Contact Information

Japan International Research Center for Agricultural Sciences (JIRCAS) (Tsukuba City, Ibaraki Prefecture)

President:
HASEGAWA Toshihiro
Program Director:
HAYASHI Keiichi
Research Staff:
OTAKA Junnosuke (Senior Researcher, Biological Resources and Post-harvest Division)
YOSHIHASHI Tadashi (Project Leader, Biological Resources and Post-harvest Division)
Guntur Venkata Subbarao (Senior Researcher, Crop, Livestock and Environment Division)
Press Coordinator:
MARUI Junichiro (Head, Public Relations Partnership Unit)
e-mail : info-pr@jircas.go.jp

National Agriculture and Food Research Organization (NARO)

Research Staff:
ONO Hiroshi and KUTSUWADA Keisuke (Research Center for Advanced Analysis, Core Technology Research Headquarters, NARO)
Press Coordinator:
SUGIYAMA Noriaki (Fundamental Technology Research Division, Director's Office, External Relations Team)

TEKMOF Co., Ltd

Research Staff:
MATSUMIYA Shigeki, WADA Naoki, WADA Yuki, KAWANO Masaki
Press Coordinator:
TSUBOI Chiaki (Representative Director & CEO)
e-mail : ctsuboi@tekmof.com

Institute of Science Tokyo

Research Staff:
WADA Yuki, KAWANO Masaki (School of Science)
Press Coordinator:
General Affairs and Planning Department, Public Relations Division
e-mail : media@adm.isct.ac.jp

Glossary

1 biological nitrification inhibition (BNI)
A phenomenon in which substances released from plant roots suppress nitrification in soil.
2 naturally occurring
Refer to compounds produced by organisms. Unlike primary metabolites (DNA, RNA, proteins), secondary metabolites (e.g., terpenoids, alkaloids) are not essential for survival but play roles in defense, environmental response, and regulation.
3 diterpenoids
A class of terpenoids composed of 20 carbon atoms, produced by plants and fungi, known for diverse biological activities such as antimicrobial and insecticidal effects.
4 nitrification
A process in which soil microorganisms convert ammonia into nitrate. While essential to the nitrogen cycle, excessive nitrification in agriculture can lead to water pollution and greenhouse gas emissions. Reducing nitrification improves nitrogen-use efficiency and environmental sustainability.
 

 

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