title: Unbiased characterization of genotype-dependent metabolic regulations by metabolomic approach in Arabidopsis thaliana.
abstract: BACKGROUND
  Metabolites are not only the catalytic products of enzymatic reactions but also the active regulators or the ultimate phenotype of metabolic homeostasis in highly complex cellular processes. The modes of regulation at the metabolome level can be revealed by metabolic networks. We investigated the metabolic network between wild-type and 2 mutant (methionine-over accumulation 1 [mto1] and transparent testa4 [tt4]) plants regarding the alteration of metabolite accumulation in Arabidopsis thaliana.
  
  
  RESULTS
  In the GC-TOF/MS analysis, we acquired quantitative information regarding over 170 metabolites, which has been analyzed by a novel score (ZMC, z-score of metabolite correlation) describing a characteristic metabolite in terms of correlation. Although the 2 mutants revealed no apparent morphological abnormalities, the overall correlation values in mto1 were much lower than those of the wild-type and tt4 plants, indicating the loss of overall network stability due to the uncontrolled accumulation of methionine. In the tt4 mutant, a new correlation between malate and sinapate was observed although the levels of malate, sinapate, and sinapoylmalate remain unchanged, suggesting an adaptive reconfiguration of the network. Gene-expression correlations presumably responsible for these metabolic networks were determined using the metabolite correlations as clues.
  
  
  CONCLUSIONS
  Two Arabidopsis mutants, mto1 and tt4, exhibited the following changes in entire metabolome networks: the overall loss of metabolic stability (mto1) or the generation of a metabolic network of a backup pathway for the lost physiological functions (tt4). The expansion of metabolite correlation to gene-expression correlation provides detailed insights into the systemic understanding of the plant cellular process regarding metabolome and transcriptome.
authors.affiliation: RIKEN Plant Science Center, 1-7-22, Yokohama, Kanagawa 230-0045, Japan. ksaito@psc.riken.jp
authors.forename: Miyako
authors.initials: M
authors.lastname: Kusano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukushima
authors.forename: Masanori
authors.initials: M
authors.lastname: Arita
authors.forename: Pär
authors.initials: P
authors.lastname: Jonsson
authors.forename: Thomas
authors.initials: T
authors.lastname: Moritz
authors.forename: Makoto
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Naomi
authors.initials: N
authors.lastname: Hayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tohge
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D053263:Gene Regulatory Networks / Q000502:physiology; D018745:Genome, Plant; D008660:Metabolism / Q000235:genetics*; D008715:Methionine / Q000096:biosynthesis; D015999:Multivariate Analysis; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018521:Plant Physiological Phenomena; D010944:Plants / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008715:Methionine