Catapol Production in Chinese Foxglove (Rehmannia glutinosa Libos.) Hairy Roots Transformed with Agrobacterium rhizogenes ATCC15834

Hairy root clones of Rehmannia glutinosa were established via transformation with Agrobacterium rhizogenes ATCC15834. To optimize the culturing conditions for both root growth and catalpol production, the effects of various combinations of seven basal media, pH, and carbon sources were examined in the dark. The fastest root growth was obtained in an SH medium containing 4% sucrose, pH 5.8. The highest catalpol content (0.54% dry weight) was achieved in a WPM medium supplemented with 4% sucrose, pH 5.8. Effects of plant growth regulators and chitosan were also investigated. Auxin 2 mg/L IAA significantly increased both root length and the frequency of lateral roots. Both 50 mg/L chitosan and 0.5 mg/L GA3 induced catalpol production, with contents calculated at 0.7% dry weight and 0.65% dry weight, respectively.