title: Evaluation of metabolic alteration in transgenic rice overexpressing dihydroflavonol-4-reductase.
abstract: OBJECTIVE
  Previous studies have shown that transgenic rice plants overexpressing YK1, which possesses dihydroflavonol-4-reductase (DFR) activity, showed biotic and abiotic stress tolerance. High throughput profiles of metabolites have also been shown in such transgenic plants by Fourier transform ion cyclotron mass spectrometry. In this study, capillary electrophoresis mass spectrometry analysis (CE/MS) was employed to identify precise metabolites such as organic acids, amino acids and sugars.
  
  
  METHODS
  Using CE/MS, we analysed several metabolites of glycolysis, the tricarboxylic acid (TCA) cycle and the pentose phosphate pathway. In addition, the concentrations of sugars and ion were quantified.
  
  
  RESULTS
  In YK1 (DFR)-overexpressing plants, the concentrations of cis-aconitate, isocitrate and 2-oxoglutarate were higher in leaves, whereas those of fructose-1,6-bisphosphate and glyceraldehyde-3-phosphate were lower in roots. In seeds, the amounts of free amino acids and metals were altered, whereas sugars in seeds were kept constant. In YK1 calli, an approx. 3-fold increase in glutathione was observed, whereas the activities of glutathione peroxidase and glutathione reductase were concomitantly increased.
  
  
  CONCLUSIONS
  The overexpression of YK1 (DFR) was associated with slight changes in the amounts of several metabolites analysed in whole plants, whilst glutathione derivatives were substantially increased in suspension-cultured cells.
authors.affiliation: Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Hayashi
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Goto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sato
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Soga
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nishioka
authors.forename: Masaru
authors.initials: M
authors.lastname: Tomita
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; D005978:Glutathione