Discovery of biological nitrification inhibitors in maize roots

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Nitrogen (N) fertilizer is an essential component for growing most crop plants. However, almost half of the applied N fertilizer is lost from soil as nitrate (NO3, a water pollutant) and as nitrous oxide (N2O, a greenhouse gas) by two microbial metabolic processes: nitrification and denitrification, respectively. To control agronomic N losses, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive natural products that can suppress nitrifying soil microbes. Our objective in this research is the identification of hydrophobic BNI compounds released from maize roots.

In the search for BNI compounds from the surface extract of maize roots, a new highly BNI active compound was discovered, together with a highly active compound. In addition, two BNI active compounds were identified from the root extract of maize (Fig. 1). The compound with the strongest BNI activity (the ability to suppress nitrification by nitrifying bacteria) was named “zeanone” because it was the first BNI compound to be discovered in nature. The four compounds, including the newly discovered zeanone, were found to have an activity equivalent to 45% of the total BNI activity of maize roots (Table 1). Based on the obtained results, a BNI mechanism in maize is proposed (Fig. 2).

The results of this research are expected to open the way for the construction of eco-friendly agricultural production systems that utilize the BNI-producing ability (BNI capacity) of maize.

Figure, table

  1. Table 1. Quantity of BNI compounds in maize roots


  2. Fig. 1. Structure and BNI activity of BNI compounds 


  3. Fig. 2. Proposed BNI mechanism in maize



    Figures and table reprinted/modified with permission from Otaka et al. (2021).





Research project
Program name


Term of research

FY 2021–2025

Responsible researcher

Otaka Junnosuke ( Biological Resources and Post-harvest Division )

Subbarao Guntur Venkata ( Crop, Livestock and Environment Division )

KAKEN Researcher No.: 00442723

Hiroshi Ono ( National Agriculture and Food Research Organization (NARO) )

KAKEN Researcher No.: 90353995

Yoshihashi Tadashi ( Crop, Livestock and Environment Division )

KAKEN Researcher No.: 60450269
MIERUKA ID: 001766

Publication, etc.

Otaka et al. (2021) Biol Fertil Soils 58: 251-264

Japanese PDF

2021_A05_ja.pdf532.83 KB

English PDF

2021_A05_en.pdf491.21 KB

Poster PDF

2021_A05_poster.pdf336.13 KB

* Affiliation at the time of implementation of the study.

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