Cytosolic Glutamine Synthetase GS1;3 Is Involved in Rice Grain Ripening and Germination

Takayuki Fujita, Marcel Pascal Beier, Mayumi Tabuchi-Kobayashi, Yoshitaka Hayatsu, Haruka Nakamura, Toshiko Umetsu-Ohashi, Kazuhiro Sasaki, Keiki Ishiyama, Emiko Murozuka, Mikiko Kojima, Hitoshi Sakakibara, Yuki Sawa, Akio Miyao, Toshihiko Hayakawa, Tomoyuki Yamaya, Soichi Kojima

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10 Citations (Scopus)


Ammonium is combined with glutamate to form glutamine. This reaction is catalyzed by glutamine synthetase (GS or GLN). Plants harbor several isoforms of cytosolic GS (GS1). Rice GS1;3 is highly expressed in seeds during grain filling and germination, suggesting a unique role in these processes. This study aimed to investigate the role of GS1;3 for rice growth and yield. Tos17 insertion lines for GS1;3 were isolated, and the nitrogen (N), amino acid, and ammonium contents of GS1;3 mutant grains were compared to wild-type grains. The spatiotemporal expression of GS1;3 and the growth and yield of rice plants were evaluated in hydroponic culture and the paddy field. Additionally, the stable isotope of N was used to trace the foliar N flux during grain filling. Results showed that the loss of GS1;3 retarded seed germination. Seeds of GS1;3 mutants accumulated glutamate but did not show a marked change in the level of phytohormones. The expression of GS1;3 was detected at the beginning of germination, with limited promoter activity in seeds. GS1;3 mutants showed a considerably decreased ripening ratio and decreased N efflux in the 12th leaf blade under N deficient conditions. The β-glucuronidase gene expression under control of the GS1;3 promoter was detected in the vascular tissue and aleurone cell layer of developing grains. These data suggest unique physiological roles of GS1;3 in the early stage of seed germination and grain filling under N deficient conditions in rice.

Original languageEnglish
Article number835835
JournalFrontiers in Plant Science
Publication statusPublished - 2022 Feb 8


  • GS1
  • amino acids
  • germination
  • grain filling
  • nitrogen translocation
  • rice
  • yield


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