Abstract
Multiple copies of flavonoid biosynthetic genes with different patterns of expression in several tissues and induction following environmental stimuli were identified in Legume. We have identified that gene duplication had occurred in the transcription factors regulating proanthocyanidin biosynthesis in model legume Lotus japonicus. Three copies of a homologue of Arabidopsis TRANSPARENT TESTA2 (TT2), which is an MYB transcription factor, were present in the Lotus japonicus genome. Transient assays suggest that three LjTT2s are different in their transcriptional activities. Chimera constructs exchanging N-terminal R2R3-MYB domain and C-terminal region of each LjTT2 revealed that R2R3-MYB domains play an important role in the activity of LjTT2. Furthermore detailed analysis using the site-directed mutagenesis indicated that three amino acid residues in R2R3-MYB domain contribute to the transcriptional activities of LjTT2s.
