Metabolomics data reveal a crucial role of cytosolic glutamine synthetase 1;1 in coordinating metabolic balance in rice.
Rice plants grown in paddy fields preferentially use ammonium as a source of inorganic nitrogen. Glutamine synthetase (GS) catalyses the conversion of ammonium to glutamine. Of the three genes encoding cytosolic GS in rice, OsGS1;1 is critical for normal growth and grain filling. However, the basis of its physiological function that may alter the rate of nitrogen assimilation and carbon metabolism within the context of metabolic networks remains unclear. To address this issue, we carried out quantitative comparative analyses between the metabolite profiles of a rice mutant lacking OsGS1;1 and its background wild type (WT). The mutant plants exhibited severe retardation of shoot growth in the presence of ammonium compared with the WT. Overaccumulation of free ammonium in the leaf sheath and roots of the mutant indicated the importance of OsGS1;1 for ammonium assimilation in both organs. The metabolite profiles of the mutant line revealed: (i) an imbalance in levels of sugars, amino acids and metabolites in the tricarboxylic acid cycle, and (ii) overaccumulation of secondary metabolites, particularly in the roots under a continuous supply of ammonium. Metabolite-to-metabolite correlation analysis revealed the presence of mutant-specific networks between tryptamine and other primary metabolites in the roots. These results demonstrated a crucial function of OsGS1;1 in coordinating the global metabolic network in rice plants grown using ammonium as the nitrogen source.
RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan.
Miyako
M
Kusano
Mayumi
M
Tabuchi
Atsushi
A
Fukushima
Kazuhiro
K
Funayama
Céline
C
Diaz
Makoto
M
Kobayashi
Naomi
N
Hayashi
Yumiko N
YN
Tsuchiya
Hideki
H
Takahashi
Atsuko
A
Kamata
Tomoyuki
T
Yamaya
Kazuki
K
Saito
D002244:Carbon / Q000378:metabolism; D002952:Citric Acid Cycle; D055786:Gene Knockout Techniques; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D055432:Metabolomics; D009154:Mutation; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development* / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis
D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D012333:RNA, Messenger; D005973:Glutamine; D002244:Carbon; D005969:Glutamate Dehydrogenase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen