Abstract
We previously reported an increase of free amino acids and enhancement of nitrogen assimilation in transgenic Arabidopsis expressing maize Dof1, a transcriptional activator for expression of the genes encoding enzymes involved in carbon skeleton production. Here, we show ammonia-dependency of the Dof1 effects. While the increase in amino acid contents was observed neither in shoots nor in roots of the Dof1 transgenic Arabidopsis grown on the medium without ammonia, a significant increase in amino acid contents was specifically detected in shoots of the transgenic Arabidopsis grown on the medium with ammonia. Furthermore, reduction in malate and fumarate contents and activation of AtPEPC1 and AtPK1 were also observed only in shoots of the transgenic Arabidopsis grown on the medium with ammonia, suggesting that the ammonia-dependent Dof1 effects are specific to shoots. The gene expression profiling for further characterization of the Dof1 transgenic Arabidopsis is currently in progress.
