Abstract
R3-type single MYB proteins have been shown to act as regulators of trichome and root hair development, but those involved in the regulation of anthocinain biosynsthesis were not known. We identified that AtMYBL2, R3-type single MYB, acts as a repressor of anthocyanin biosynthesis in Arabidopsis. Ectopic expression of AtMYBL2 and the chimeric AtMYBL2 repressor both suppressed accumulation of anthocyanin in rosette leaves, while AtMYBL2 knock-out line prominently enhanced expression of DFR and TT8 genes, with resultant ectopic deposition of anthocyanins. We found that the six amino acids of TLLLFR at the C-terminal end of AtMYBL2 act as repression domain. mybl2 phenotype was complemented by 35S:AtMYBL2, while AtMYBL2 from which the repression domain was deleted failed to complement. Promoter activities of AtMYBL2 were detected ubiquitously in many tissues of aerial parts. We discuss function of AtMYBL2 as a repressor and its functional involvement in the regulation of anthocyanin biosynthesis.
