| Nitrogen is the main limiting component to plant growth and development. With increasing cost of food production the development of nitrogen use efficient (NUE) crop plants has become of interest. In our group, the over-expression of barley alanine amino transferase (HvAlaAT) cDNA by the btg26 and OsANT1 promoters has yielded NUE plants. Through a detailed bioinformatic analysis, the PBpr1 promoter was selected, cloned, and coupled to HvAlaAT for over-expression in rice ( Oryza sativa cv. Nipponbare). Overall, rice lines carrying PBpr1::HvAlaAT resulted in higher seed yield, biomass and tillering compared to non-transformed Nipponbare. Molecular analysis of these lines showed high levels of HvAlaAT mRNA and alanine aminotransferase (AlaAT) protein. Transgenic shoots exhibits high levels of AlaAT activity at all times while root activity increased only after active tillering, indicating developmental regulation of the gene in roots. Analysis of PBpr1 pattern expression, however, showed no definitive staining despite the observed over-expression of HvAlaAT at the transcript and enzyme activity level. |
