Blue and White LED Lights Enhance Biosynthesis of Rosmarinic Acid in Cell Culture of Agastache rugosa

Agastache rugosa, an herbaceous Korean perennial, contains pharmacologically important phenylpropanoids such as tilianin and rosmarinic acid. However, the knowledge of biosynthesis of phenylpropanoids from A. rugosa is limited. Therefore, a study was conducted to develop an efficient protocol for in vitro regeneration of A. rugosa and to investigate the influence of three different LED light wavelengths (white, blue and red) on the biosynthesis of phenylpropanoids, including altered gene expression and variance in rosmarinic acid accumulation in calli. Transcription analyses revealed that white LED light enhances RAS expression; transcript levels were 15.7- and 10.4-fold higher for calli treated with white LED light than for those treated with red and blue light, respectively. Similarly, HPPR and C4H were also more highly expressed under blue and white LED light. In addition, HPLC quantification assays indicated that the highest levels of rosmarinic acid accumulate in calli treated with blue, red and white light (in that order) one week after cultivation. Together, our gene expression and HPLC quantification results provide evidence that rosmarinic acid in A. rugosa increases with the application of various wavelengths of LED light.