Evaluation of metabolic alteration in transgenic rice overexpressing dihydroflavonol-4-reductase.
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.
Takahashi
Hideyuki
H
Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Hayashi
Mitsunori
M
Goto
Fumiyuki
F
Sato
Shigeru
S
Soga
Tomoyoshi
T
Nishioka
Takaaki
T
Tomita
Masaru
M
Kawai-Yamada
Maki
M
Uchimiya
Hirofumi
H
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
D000596:Amino Acids; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; D005978:Glutathione