Identification of the key biological nitrification inhibition (BNI) compound from maize roots
Related Research Project
BNI-system
Description
Specific plants can suppress nitrification in soil by releasing inhibitory natural products from their roots, a chemical-ecological phenomenon called biological nitrification inhibition (BNI). BNI utilization is a useful strategy for solving environmental problems (e.g., water pollution by NO3; production of the greenhouse gas N2O) and improving nitrogen uptake while reducing nitrogen losses from agricultural fields. The crucial property for the isolation of BNI compounds is whether their root exudates, extracts, and compounds are water-insoluble (hydrophobic) or water-soluble (hydrophilic). While hydrophobic compounds with lower mobility are retained in the rhizosphere, hydrophilic compounds can move further away from the roots. In a previous study, two major hydrophobic BNI-contributing compounds from the root surface (zeanone and HDMBOA) were identified in maize, together with two analogs of HDMBOA from inside the roots (Fig. 1). Our objective in this study is to identify the chemical structure and function of a hydrophilic BNI-active compound from maize.
The most BNI-active compound in hydrophilic BNI-activity from maize roots was identified as 6-methoxy-2(3H)-benzoxazolone (MBOA). MBOA has been detected in several Poaceae species such as maize and wheat. MBOA strongly inhibited the growth of Nitrosomonas europaea (Fig. 2). In a soil incubation experiment, NO3 production was suppressed in the presence of MBOA during incubation for 4 days, and BNI-activity declined in parallel with MBOA biodegradation after incubation for 5 days (Fig. 3). Further experiments suggested that two benzoxazinoids, HDMBOA and HDMBOA-β-glucoside, which are chemically and biologically unstable in soil, respectively, could be converted into the more stable BNI-active MBOA in the soil (Fig. 4). Therefore, MBOA is a key component in the BNI-activity of maize.
MBOA is degraded in soil via microbial reaction, while new MBOA can be constantly produced and released by living maize. Hence, maize can stably exhibit BNI activity. The BNI compounds identified in our study are a promising indicator for evaluating BNI capacity among maize species, and can lead to the development of BNI-enhanced maize.
Figure, table
- Research project
- Program name
- Term of research
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FY2021-2023
- Responsible researcher
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Otaka Junnosuke ( Biological Resources and Post-harvest Division )
Tadashi Yoshihashi ( Biological Resources and Post-harvest Division )
Subbarao Guntur Venkata ( Crop, Livestock and Environment Division )
ORCID ID0000-0002-7243-6394KAKEN Researcher No.: 00442723MingLi Jiang ( Crop, Livestock and Environment Division )
Hiroshi Ono ( National Agriculture and Food Research Organization (NARO) )
- ほか
- Publication, etc.
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Otaka et al. (2023) Plant and Soil 489: 341–359.https://doi.org/10.1007/s11104-023-06021-7
- Japanese PDF
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2023_A04_ja.pdf1.17 MB
- English PDF
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2023_A04_en.pdf628.33 KB
＊ Affiliation at the time of implementation of the study.