Optimization of elicitors and precursors to enhance valtrate production in adventitious roots of Valeriana amurensis Smir. ex Kom

Valeriana amurensis Smir. ex Kom. is a traditional Chinese medicinal plant as its roots serve as a rich source of valtrate, a compound with antifungal cytotoxic sedation and tranquilizing activities. In this study, an adventitious root culture of V. amurensis was established, and the effects of different elicitors, including salicylic acid (SA), chitosan (CH), jasmonic acid (JA), methyl jasmonate (MJ), yeast extract (YE), and yeast extract carbohydrate fraction (YECF) along with the precursor citronellal (CI) on production of valepotriates were assayed. MJ and JA highly promoted valtrate production; while, CH moderately promoted valtrate production. In contrast, CI, SA, YE, and YECF were ineffective in promoting valtrate production. Using a response surface methodology, optimal combinations of MJ, JA, and CH were shown to have strong synergistic effects on valtrate production, and this was subsequently confirmed in experimental studies.