Effects of 2-Hydroxypropyl-β-cyclodextrin and 28-Homobrassinolide on the Physiological Characteristics，gene expression and Terpenoid Indole Alkaloids Accumulation in Catharanthus roseus  Cambial Meristematic Cell Cultures

Compared with callus culture, Catharanthus roseus (CAT) cambial meristematic cells (CMCs) cultured in vitro exhibit high production of pharmacologically active terpenoid indole alkaloids (TIA). Elicitors can significantly promote the biosynthesis of secondary metabolites in plant cells. However, the regulation of alkaloid biosynthesis in C. roseus CMCs by elicitors 2-Hydroxypropyl- β-cyclodextrin (H-β-CD) and 28-Homobrassinolide (HBL) is still unknown. Therefore, we established a new cambial meristematic cell line, named C. roseus CMCs-2, and investigated the effects of H-β-CD and HBL individually or in combination on the TIA content of CMCs in Erlenmeyer flasks (100, 250 and 500 mL) or in a 5-L airlift bioreactor.CMCs cultured in the bioreactor and treated with 10.0 g/L H-β-CD and 150 μg/L HBL gave the highest yields of vindoline (4.89 mg/L), catharanthine (2.49 mg/L) vinblastine (3.96 mg/L) and ajmalicine (3.87 mg/L), concentrations that were 241, 277, 165 and 110 % higher, respectively, than yields of CMCs cultured in 100-mL flasks without elicitors. These results indicated that CMCs cultured in the bioreactor exhibited enhanced production of vindoline, catharanthine, vinblastine and ajmalicine than those cultured in flasks. Quantitative RT-PCR showed that H-β-CD and HBL up-regulated transcription levels of genes related to the biosynthesis of TIAs. These results imply that H-β-CD and HBL can boost TIA production in CMCs, thereby indicating that C. roseus CMCs have considerable potential as an industrial platform for the production of bioactive TIAs.