Vinblastine and vincristine are two important anti-cancer drugs that are synthesized by the Terpenoid Indole Alkaloids (TIAs) pathway in periwinkle (Catharanthus roseus). The major challenge in the pharmaceutical industry is the low production rate of these Alkaloids. TIA pathway is affected by elicitors, such as salicylic acid (SA). This study aimed to investigate the expression pattern of some key genes in TIAs pathway under SA treatment. Foliar application of SA (0.01 and 0.1 mM) was used and leaves samples were taken at 0, 12, 18, 24 and 48 h after the treatment. qRT-PCR was used to investigate the expression pattern of Chorismate mutase (Cm), tryptophan decarboxylase (Tdc), Geraniol-10-hydroxylase (G10h), Secologanin synthase (Sls), Strictosidine synthase (Str), Desacetoxyvindoline-4-hydroxylase (D4h) and Deacetylvindoline-4-O-acetyltransferase (Dat) genes, following the SA treatment. The results of this experiment showed that transcript levels of Tdc, G10h, Sls, Str, D4h and Dat genes were significantly up-regulated in both SA concentration treatments. Furthermore, the highest transcript levels of Dat was observed after 48 h of the SA treatments. qRT-PCR results suggests that SA induces transcription of major genes involved in Alkaloids biosynthesis in Catharanthus roseus. It can be concluded that up-regulation of Tdc, G10h, Sls, Str, D4h and Dat genes can result in a higher production rate of Vinblastine and vincristine Alkaloids.
Keywords: Elicitor; Gene expression; Salicylic Acid; TIAs pathway; Terpenoid Indole Alkaloids; qRT-PCR.