A supply of nitrogen causes increase in the level of NADH-dependent glutamate synthase protein and in the activity of the enzyme in roots of rice seedlings

Tomoyuki Yamaya, Hiromi Tanno, Naoya Hirose, Sachiko Watanabe, Toshihiko Hayakawa

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

When rice seedlings, after the growth for 26 days in water alone, were transferred to nutrient medium contained 1 mM NH4Cl, the level of NADH-dependent glutamate synthase (GOGAT) protein and the activity of the enzyme increased more than 10-fold in root, but not in shoots. Both the level of the protein and the activity reached a maximum within 24 h. NH4Cl was effective at concentrations as low as 50 μM. A supply of either 1 mM NaNO3 or 0.5 mM NH4NO3 also caused such increases, but NHa4Cl was most effective. A supply of glutamine or glutamate was less effective. The increase was specific to NADH-GOGAT and little change was observed in the levels of ferredoxin-GOGAT and glutamine synthetase isoproteins in roots. These inducible increases in the levels of NADH-GOGAT protein and in its activity were greater in the root-tip region than at the base of the root. Both 6-methylpurine and cycloheximide completely inhibited the effects of NH4Cl. Moreover, the mRNA for NADH-GOGAT in rice roots accumulated markedly within 12 h of the start of a supply of NH4Cl. A possible role for the rapid response of NADH-GOGAT to a supply of NH4C1 is discussed.

Original languageEnglish
Pages (from-to)1197-1204
Number of pages8
JournalPlant and Cell Physiology
Volume36
Issue number7
Publication statusPublished - 1995 Oct

Keywords

  • NADH-glutamate synthase (EC 1.4.1.14)
  • Nitrogen supply
  • Oryza sativa
  • Rice root

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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