Nitrogen-dependent regulation of de novo cytokinin biosynthesis in rice: the role of glutamine metabolism as an additional signal

Plant Cell Physiol. 2013 Nov;54(11):1881-93. doi: 10.1093/pcp/pct127. Epub 2013 Sep 20.


Cytokinin activity in plants is closely related to nitrogen availability, and an Arabidopsis gene for adenosine phosphate-isopentenyltransferase (IPT), IPT3, is regulated by inorganic nitrogen sources in a nitrate-specific manner. In this study, we have identified another regulatory system of cytokinin de novo biosynthesis in response to nitrogen status. In rice, OsIPT4, OsIPT5, OsIPT7 and OsIPT8 were up-regulated in response to exogenously applied nitrate and ammonium, with accompanying accumulation of cytokinins. Pre-treatment of roots with l-methionine sulfoximine, a potent inhibitor of glutamine synthetase, abolished the nitrate- and ammonium-dependent induction of OsIPT4 and OsIPT5, while glutamine application induced their expression. Thus, neither nitrate nor ammonium, but glutamine or a related metabolite, is essential for the induction of these IPT genes in rice. On the other hand, glutamine-dependent induction of IPT3 occurs in Arabidopsis, at least to some extent. In transgenic lines repressing the expression of OsIPT4, which is the dominant IPT in rice roots, the nitrogen-dependent increase of cytokinin in the xylem sap was significantly reduced, and seedling shoot growth was retarded despite sufficient nitrogen. We conclude that plants possess multiple regulation systems for nitrogen-dependent cytokinin biosynthesis to modulate growth in response to nitrogen availability.

Keywords: Ammonium; Arabidopsis thaliana; Cytokinin; Glutamine; Nitrate; Oryza sativa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkyl and Aryl Transferases / genetics*
  • Alkyl and Aryl Transferases / metabolism
  • Ammonium Compounds / metabolism
  • Arabidopsis / cytology
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Base Sequence
  • Cytokinins / metabolism*
  • Gene Expression Regulation, Plant*
  • Glutamine / metabolism*
  • Molecular Sequence Data
  • Nitrates / metabolism
  • Nitrogen / metabolism
  • Oryza / cytology
  • Oryza / genetics*
  • Oryza / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Plant Roots / cytology
  • Plant Roots / genetics
  • Plant Roots / metabolism
  • Plant Shoots / cytology
  • Plant Shoots / genetics
  • Plant Shoots / metabolism
  • Plant Vascular Bundle / cytology
  • Plant Vascular Bundle / genetics
  • Plant Vascular Bundle / metabolism
  • Plants, Genetically Modified
  • Recombinant Fusion Proteins
  • Seedlings / cytology
  • Seedlings / genetics
  • Seedlings / metabolism
  • Sequence Analysis, DNA
  • Signal Transduction
  • Species Specificity


  • Ammonium Compounds
  • Cytokinins
  • Nitrates
  • Plant Proteins
  • Recombinant Fusion Proteins
  • Glutamine
  • Alkyl and Aryl Transferases
  • adenylate isopentenyltransferase
  • Nitrogen

Associated data

  • GENBANK/AB853903