title: Detection, isolation and characterization of a root-exuded compound, methyl 3-(4-hydroxyphenyl) propionate, responsible for biological nitrification inhibition by sorghum (Sorghum bicolor).
abstract: 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 (IC(70)) 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 supply. NH4+ -grown plants released several-fold higher BNI compounds than NO3- -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 NH4+. 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.
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Hossain A K M
authors.initials: HAKM
authors.lastname: Zakir
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Guntur V
authors.initials: GV
authors.lastname: Subbarao
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.|School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Pearse
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Gopalakrishnan
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Crop production & Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Naoyoshi
authors.initials: N
authors.lastname: Kawano
authors.affiliation: Food Science & Technology Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakahara
authors.affiliation: Food Science & Technology Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305-8686, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshihashi
authors.affiliation: National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ono
authors.affiliation: National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yoshida
mesh_terms: D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D019811:Hydroxylamine / Q000494:pharmacology; D015394:Molecular Structure; D009584:Nitrogen / Q000378:metabolism*; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D053147:Plant Exudates; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D011422:Propionates / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D045868:Sorghum / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D010636:Phenols; D053147:Plant Exudates; D011422:Propionates; C535177:methyl 3-(4-hydroxyphenyl)propionate; D019811:Hydroxylamine; D009584:Nitrogen