Functional differentiation of Lotus japonicus TT2s, R2R3-MYB transcription factors comprising a multigene family.
Leguminous plants have many paralogous genes encoding enzymes involved in the flavonoid biosynthetic pathway. Duplicate genes are predicted to contribute to the production of various flavonoid compounds and to have resulted in a diversity of legume species. We identified gene duplication in the transcription factors regulating flavonoid biosynthesis in the model legume Lotus japonicus. Three copies of a homolog of Arabidopsis thaliana TRANSPARENT TESTA2 (TT2), which is a MYB transcription factor that regulates proanthocyanidin biosynthesis, were present in the L. japonicus genome. The organ specificity and stress responsiveness differed among the three LjTT2s, and correlations between proanthocyanidin accumulation and the expression levels of LjTT2s were observed during seedling development. Moreover, three LjTT2s functionally complemented TT2 in transient expression experiments in A. thaliana leaf cells. The different reporter activity caused by LjTT2a was consistent with the affinity of physical interactions with TT8 and TTG1 in yeast two-hybrid experiments as well as the branching pattern of the phylogenetic tree. These results suggest that LjTT2 factors have diverse functions in the tissues in which they are expressed; in particular, LjTT2a is predicted to have evolved flexibility in interaction with other transcription regulators to resist environmental stresses.
Yoshida
Kazuko
K
Department of Biology, Ochanomizu University, Tokyo 112-8610 Japan.
Iwasaka
Rieko
R
Kaneko
Takakazu
T
Sato
Shusei
S
Tabata
Satoshi
S
Sakuta
Masaaki
M
D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D000070116:Lotus / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D010940:Plant Proteins; D014157:Transcription Factors