title: Using metabolomic approaches to explore chemical diversity in rice.
abstract: Rice (Oryza sativa) is an excellent resource; it comprises 25% of the total caloric intake of the world's population, and rice plants yield many types of bioactive compounds. To determine the number of metabolites in rice and their chemical diversity, the metabolite composition of cultivated rice has been investigated with analytical techniques such as mass spectrometry (MS) and/or nuclear magnetic resonance spectroscopy and rice metabolite databases have been constructed. This review summarizes current knowledge on metabolites in rice including sugars, amino and organic acids, aromatic compounds, and phytohormones detected by gas chromatography-MS, liquid chromatography-MS, and capillary electrophoresis-MS. The biological properties and the activities of polar and nonpolar metabolites produced by rice plants are also presented. Challenges in the estimation of the structure(s) of unknown metabolites by metabolomic approaches are introduced and discussed. Lastly, examples are presented of the successful application of metabolite profiling of rice to characterize the gene(s) that are potentially critical for improving its quality by combining metabolite quantitative trait loci analysis and to identify potential metabolite biomarkers that play a critical role when rice is grown under abiotic stress conditions.
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan. Electronic address: miyako.kusano@riken.jp.
authors.forename: Miyako
authors.initials: M
authors.lastname: Kusano
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Yang
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yozo
authors.initials: Y
authors.lastname: Okazaki
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakabayashi
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukushima
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Chiba 260-8675, Japan. Electronic address: kazuki.saito@riken.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
mesh_terms: D055432:Metabolomics / Q000379:methods*; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism
chemical_list: D010940:Plant Proteins
keywords: Oryza sativa; QTL analysis; chemical diversity; gene discovery; mass spectrometry; metabolomics