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An ornithine δ-aminotransferase gene OsOAT confers multi-stress tolerance in rice[1].

Annotated Information


  • OsOAT is a direct target of the stress-responsive NAC transcription factor SNAC2[2]. OsOAT is responsive to multiple stresses and phytohormone treatments mainly through enhancing ROS-scavenging capacity and Pro pre-accumulation. Both ABA-dependent and ABA-independent pathways contributed to the drought-induced expression of OsOAT[1].
  • OsOAT encodes a putative ornithine δ-aminotransferase, was upregulated' in SNAC2-overexpressing plants[2]. SNAC2 could bind to the promoter fragment of OsOAT[1].

GO assignment(s): GO:0008483,GO:0030170


Three independent transgenic lines[1]:

  • OsOAT-OE-7
  • OsOAT-OE-10
  • OsOAT-OE-17
  • The δ-OAT activity was significantly higher in the OsOAT overexpressing lines than in wild-type.
  • Under normal moisture conditions, the OsOAT overexpressing plants accumulated significantly more Pro than wild-type.
  • Under drought stress conditions, the free Pro content increased in both the transgenic and wild-type plants. However, the Pro content in the OsOAT-overexpressing lines was slightly lower than that in the wild-type under drought stress conditions.
  • The glutathione (GSH) content and activity of reactive oxygen species (ROS)-scavenging enzymes, such as glutathione peroxidase, were also increased in OsOAT-overexpressing plants.


  • Overexpression of the OsOAT gene in rice resulted in significantly enhanced drought and osmotic stress tolerance. Overexpression of OsOAT caused significantly increased δ-OAT activity and Pro accumulation under normal growth conditions. In addition, OsOAT overexpressing plants showed significantly increased tolerance to oxidative stress[1].
  • The transcript of OsOAT was induced in leaves 3 d after the initiation of drought stress, and the induction increased on day 5 and was maintained on day 7 of the drought stress experiment. The OsOAT transcript was also induced by high-salinity, heat, and submergence. transcript of OsOAT was strongly induced by ABA and IAA, and it was slightly induced by BR and JA[1].


OsOAT has only one splicing mode and contains a 1422 bp open reading frame, which is predicted to encode a 473 amino acid protein with a molecular mass of 51.45 kDa. Accordingly, a putative N-terminal transit peptide with a barely conserved sequence for mitochondrial targeting exists in plant and animal δ-OATs including OsOAT. However, such an N-terminal sequence is absent in the δ-OATs from fungal and bacterial species[1].

Knowledge Extension

  • OAT is a mitochondrial enzyme containing pyridoxal-5′-phosphate as a cofactor, which catalyzes the conversion of L-ornithine to L-glutamate γ-semialdehyde using 2-oxoglutarate as a terminal amino group acceptor. It has been described in humans, animals, insects, plants and microorganisms[3].
  • Based on the crystal structure of human OAT, both substrate binding and reaction mechanism of the enzyme are well understood[3].
  • OAT shows a large structural and mechanistic similarity to other enzymes from the subgroup III of aminotransferases, which transfer an amino group from a carbon atom that does not carry a carboxyl function. In plants, the enzyme has been implicated in proline biosynthesis and accumulation (via pyrroline-5-carboxylate), which represents a way to regulate cellular osmolarity in response to osmotic stress. However, the exact metabolic pathway involving OAT remains a subject of controversy[3].

Labs working on this gene

  • National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 You J, Hu H, Xiong L. An ornithine δ-aminotransferase gene OsOAT confers drought and oxidative stress tolerance in rice[J]. Plant Science, 2012, 197: 59-69.
  2. 2.0 2.1 Hu H, You J, Fang Y, et al. Characterization of transcription factor gene SNAC2 conferring cold and salt tolerance in rice[J]. Plant molecular biology, 2008, 67(1-2): 169-181.
  3. 3.0 3.1 3.2 Stránská J, Kopečný D, Tylichová M, et al. Ornithine δ-aminotransferase: an enzyme implicated in salt tolerance in higher plants[J]. Plant signaling & behavior, 2008, 3(11): 929-935.

Structured Information