Nitrogen-efficient rice over-expressing alanine aminotransferase

Oryza sativa cv. Nipponbare was engineered to over-express a barley alanine aminotransferase (alaAT) gene using the promoter (OsANT1) from a rice aldehyde dehydrogenase gene that expresses in roots. We are using biotechnology to improve the nitrogen use efficiency of rice by over-expressing alaAT in a tissue specific (root) manner. The AlaAT enzyme is a reversible aminotransferase that is linked to both C and N metabolism since it uses pyruvate plus glutamate to produce alanine and 2-oxoglutarate, and visa versa. Wildtype rice (Nipponbare) and three independent OsANT1:HvAlaAT rice transgenic lines (AGR1/7, AGR1/8 and AGR3/8) were grown hydroponically with 5mM NH4+ as the nitrogen source, to the reproductive stage. RNA samples were taken at active tillering, maximum tillering and end-of-tillering stages from root and shoot, at mid-day of the plants' day/night cycle. The RNA from root and shoot at maxiumum tillering was used for microarray analysis. Please read Beatty et al., 2009, Plant Biotechnology Journal 7, pp562-576 for further details..