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

作者：YAMAYA T^*; TANNO H; HIROSE N; WATANABE S; HAYAKAWA T

来源：Plant and Cell Physiology, 1995, 36(7): 1197-1204.

• NADH-GLUTAMATE SYNTHASE (EC 1.4.1.14)
• NITROGEN SUPPLY
• ORYZA SATIVA
• RICE ROOT

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 mu M. A supply of either 1 mM NaNO3 or 0.5 mM NH4NO3 also caused such increases, but NH4Cl 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 NH4Cl is discussed.

• 出版日期1995-10