TY - JOUR
T1 - Expression of NADH-dependent glutamate synthase protein in the epidermis and exodermis of rice roots in response to the supply of ammonium ions
AU - Ishiyama, Keiki
AU - Hayakawa, Toshihiko
AU - Yamaya, Tomoyuki
N1 - Funding Information:
We thank Dr. Ann Oaks, University of Guelph, Canada, and Dr. Alyson K. Tobin, University of St. Andrews, UK, for their helpful comments and critical reading of the manuscript. This work was supported in part by a program of Research for the Future from the Japan Society for the Promotion of Science (JSPS-RFTF96L00604), in part by Grant-in-Aid for Scientific Research on Priority Area (Nos. 09274101 and 09274102), and in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (No. 08044187).
PY - 1998/3
Y1 - 1998/3
N2 - The mRNA and protein for NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14) in root tips of rice (Oryza sativa L. cv. Sasanishiki) plants increases dramatically within 12 h of supplying a low concentration (> 0.05 mM) of ammonium ions (T. Yamaya et al., 1995, Plant Cell Physiol 36:1197-1204). To identify the specific cells which are responsible for this rapid increase, the cellular localization of NADH-GOGAT protein was investigated immunocytologically with an affinity-purified anti-NADH-GOGAT immunoglobulin G. When root tips (>1 mm) of rice seedlings which had been grown for 26 d in water were immunostained, signals for the NADH-GOGAT protein were detected in the central cylinder, in the apical meristem, and in the primordia of the secondary roots. Signals for ferredoxin-dependent GOGAT (Fd-GOGAT; EC 1.4.7.1) protein were also seen in the same three areas. When the roots were supplied with 1 mM ammonium ions for 24 h, there were strong signals for the NADH-GOGAT protein in two cell layers of the root surface, i.e. epidermis and exodermis, in addition to the cells giving signals in the absence of ammonium ions. The supply of ammonium ions was less effective on the profile of signals for Fd-GOGAT. Although the supply of ammonium ions had less effect on the expression of cytosolic glutamine synthetase (GS; EC 6.3.1.2), this enzyme was also found to be located in the epidermis and exodermis, as well as in the central cylinder and cortex. The results indicate that NADH-GOGAT, coupled to the cytosolic GS reaction, is probably important for the assimilation of ammonium ions in the two cell layers of the root surface.
AB - The mRNA and protein for NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14) in root tips of rice (Oryza sativa L. cv. Sasanishiki) plants increases dramatically within 12 h of supplying a low concentration (> 0.05 mM) of ammonium ions (T. Yamaya et al., 1995, Plant Cell Physiol 36:1197-1204). To identify the specific cells which are responsible for this rapid increase, the cellular localization of NADH-GOGAT protein was investigated immunocytologically with an affinity-purified anti-NADH-GOGAT immunoglobulin G. When root tips (>1 mm) of rice seedlings which had been grown for 26 d in water were immunostained, signals for the NADH-GOGAT protein were detected in the central cylinder, in the apical meristem, and in the primordia of the secondary roots. Signals for ferredoxin-dependent GOGAT (Fd-GOGAT; EC 1.4.7.1) protein were also seen in the same three areas. When the roots were supplied with 1 mM ammonium ions for 24 h, there were strong signals for the NADH-GOGAT protein in two cell layers of the root surface, i.e. epidermis and exodermis, in addition to the cells giving signals in the absence of ammonium ions. The supply of ammonium ions was less effective on the profile of signals for Fd-GOGAT. Although the supply of ammonium ions had less effect on the expression of cytosolic glutamine synthetase (GS; EC 6.3.1.2), this enzyme was also found to be located in the epidermis and exodermis, as well as in the central cylinder and cortex. The results indicate that NADH-GOGAT, coupled to the cytosolic GS reaction, is probably important for the assimilation of ammonium ions in the two cell layers of the root surface.
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U2 - 10.1007/s004250050258
DO - 10.1007/s004250050258
M3 - Article
C2 - 9530872
AN - SCOPUS:0032031334
SN - 0032-0935
VL - 204
SP - 288
EP - 294
JO - Planta
JF - Planta
IS - 3
ER -