Effects of PEG-induced drought stress on regulation of indole alkaloid biosynthesis in Catharanthus roseus

Catharanthus roseus (C. roseus) plants were used to investigate the terpenoid indole alkaloids (TIAs) accumulation under the condition of PEG-induced drought stress. Multivariate analysis showed that 35% PEG6000 could induce more obvious and stable accumulation on proline (PRO) content and the relative water content (RWC). The results indicated that there were gradual increase and then decrease (p < .05) in the contents of vindoline (VIN) and catharanthine (CAT) under 35% PEG6000 stress, but the content of vinblastine (VBL) increased gradually. In addition, the expression levels of tryptophan decarboxylase (TDC), strictosidine synthase (STR) and deacetylvindoline-4-O-acetyltransferase (DAT) were upregulated in plants under 35% PEG6000 stress. Further correlation analysis indicated that CAT accumulation was significantly correlated with TDC gene expression, and VBL accumulation was significantly correlated with peroxidase (p < .05). Our results suggest that the cultivation of C. roseus in drought stress would serve as effective treatment for accumulating TIAs.