Detection, isolation and characterization of a root-exuded compound, methyl 3-(4-hydroxyphenyl) propionate, responsible for biological nitrification inhibition by sorghum (Sorghum bicolor)

Authors

  • Hossain A. K. M. Zakir,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Guntur V. Subbarao,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Stuart J. Pearse,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
    2. School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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  • Subramaniam Gopalakrishnan,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Osamu Ito,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Takayuki Ishikawa,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Naoyoshi Kawano,

    1. Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Kazuhiko Nakahara,

    1. Food Science & Technology Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Tadashi Yoshihashi,

    1. Food Science & Technology Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan;
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  • Hiroshi Ono,

    1. National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan;
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  • Mitsuru Yoshida

    1. National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan;
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Author for correspondence:
Guntur V. Subbarao
Tel/Fax: +81 29 838 6354
Email: subbarao@jircas.affrc.go.jp

Summary

  • • Nitrification results in poor nitrogen (N) recovery and negative environmental impacts in most agricultural systems. Some plant species release secondary metabolites from their roots that inhibit nitrification, a phenomenon known as biological nitrification inhibition (BNI). Here, we attempt to characterize BNI in sorghum (Sorghum bicolor).
  • • In solution culture, the effect of N nutrition and plant age was studied on BNI activity from roots. A bioluminescence assay using recombinant Nitrosomonas europaea was employed to determine the inhibitory effect of root exudates. One major active constituent was isolated by activity-guided HPLC fractionations. The structure was analysed using NMR and mass spectrometry. Properties and the 70% inhibitory concentration (IC70) of this compound were determined by in vitro assay.
  • • Sorghum had significant BNI capacity, releasing 20 allylthiourea units (ATU) g−1 root DW d−1. Release of BNI compounds increased with growth stage and concentration of inline image supply. inline image-grown plants released several-fold higher BNI compounds than inline image-grown plants. The active constituent was identified as methyl 3-(4-hydroxyphenyl) propionate.
  • • BNI compound release from roots is a physiologically active process, stimulated by the presence of inline image. Methyl 3-(4-hydroxyphenyl) propionate is the first compound purified from the root exudates of any species; this is an important step towards better understanding BNI in sorghum.

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