Abstract
We previously reported that expression of the OsMYB-NR2 transcription factor gene was rapidly induced by nitrate supply in rice. To identify the target genes of OsMYB-NR2, we generated transgenic callus overexpressing OsMYB-NR2 and performed microarray analysis using the callus. Based on the result obtained, we selected candidates for the target genes, and examined whether the promoters of these genes could be really transactivared by OsMYB-NR2. Transactivation assays using maize protoplasts revealed that OsMYB-NR2 can transactivate the promoters of genes for tryptophan synthase α subunit involved in tryptophan biosynthesis and for tryptophan decarboxylase catalyzing the first step in the tryptophan secondary metabolism. Contents of tryptophan and serotonin, one of the secondary metabolites of tryptophan, were measured and the physiological function of OsMYB-NR2 was discussed. This work was supported in parts by grants from the Program for promotion of Basic Research Activities for Innovative Biosciences.
