Changes in the cellular localization of cytosolic glutamine synthetase protein in vascular bundles of rice leaves at various stages of development

Nozomu Sakurai, Toshihiko Hayakawa, Teiji Nakamura, Tomoyuki Yamaya

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

Cellular localization of cytosolic glutamine synthetase (GS1: EC 6.3.1.2) in vascular bundles of leaf blades of rice (Oryza sativa L.) at the stage at which leaf blades 6 (the lowest position) to 10 were fully expanded, was investigated immunocytologically with an affinity-purified anti-GS1 immunoglobulin G. Strong signals for GS1 protein were detected in companion cells of large vascular bundles when blades 6-8 were tested. Signals for GS1 were also observed in vascular-parenchyma cells of both large and small vascular bundles. The results further support our hypothesis that GS1 is important for the export of leaf nitrogen from senescing leaves. The signals in companion cells were less striking in the younger green leaves and were hardly detected in the non-green portion of the 11th blade. In the non-green blades, strong signals for GS1 protein were detected in sclerenchyma and xylem-parenchyma cells. When total GS extracts prepared from the 6th, 10th, and the non-green 11th blades were subjected to anion-exchange chromatography, the activity of GS1 was clearly separated from that of chloroplastic GS, indicating that GS1 proteins detected in the vascular tissues were able to synthesize glutamine. The function of GS1 detected in the developing leaves is discussed.

Original languageEnglish
Pages (from-to)306-311
Number of pages6
JournalPlanta
Volume200
Issue number3
DOIs
Publication statusPublished - 1996 Nov

Keywords

  • Enzyme localization
  • Glutamine synthetase
  • Nitrogen remobilization
  • Oryza
  • Vascular bundle

ASJC Scopus subject areas

  • Genetics
  • Plant Science

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