Abstract
We have been investigating the transport mechanism of berberine alkaloid using Coptis japonica (Ranunculaceae), as a model plant. In C. japonica, berberine is biosynthesized in root, but is highly accumulated in the rhizome as the main alkaloid, suggesting that berberine is translocated from the root into the rhizome. We have recently reported that an MDR type ABC protein, CjMDR1, functions as a berberine influx transporter in the rhizome. To further clarify the physiological function of CjMDR1 in planta, we produced transgenic C. japonica plants with modified expression of Cjmdr1. In fact, the introduction of 35S promoter drived Cjmdr1 sense construct produced a transgenic plant (Sense-2) with reduced expression of Cjmdr1. Since this transgenic C. japonica plant showed stable reduction of Cjmdr1 expression, we are now characterizing the effect of Cjmdr1 expression on the accumulation of berberine as well as the expression of biosynthetic genes.
