Abstract
OsMYB-NR2 is a nitrogen-inducible transcription factor in rice. We previously reported that MYB-NR2 activated the promoters of two genes related to tryptophan metabolism and that serotonin was accumulated in the transgenic rice overexpressing MYB-NR2 (MYB-NR2OX). In this study, we show that the phenylalanine content in shoots of MYB-NR2OX was also higher by 1.5 times, compared with the content in the vector control plants. The result of DNA microarray analysis using transgenic callus indicated that the expression of the gene for arogenate dehydrogenase that catalyzes the final step of phenylalanine biosynthesis was promoted in MYB-NR2OX, together with expressions of more than 20 genes associated with the synthetic pathway of second metabolites derived from phenylalanine. Furthermore, in the 5' upstream regions of these genes, we found multiple copies of the recognition sequence of MYB-NR2 that was identified by the DNA binding site selection experiment. Based on these findings, we discuss on the possible role of MYB-NR2 in phenylalanine metabolism. This work was supported in parts by grants from the Program for promotion of Basic Research Activities for Innovative Biosciences.
