Relative expression of the key genes of Diosegnin biosynthesis in fenugreek (Trigonella foenum-graesum) in response to salicylic acid and methyl jasmonat

Fenugreek is an important medicinal plants that has valuable secondary metabolites. Diosgenin, a steroid saponin, occurs abundantly in fenugreek which has many medicinal properties. Anticancer activity of diosgenin has been reported in many studies. In this study the expression of some key genes involved in the biosynthesis of diosgenin, was assessed. First, plants (before flowering stage) were treated with 0.5 mM methyl jasmonate and 1 mM salicylic acid in separate experiments. Then, at 0, 12, 24, and 48 hours after treatment, leaves were sampled for further investigation. The total RNA was extracted from the leaves and afterward cDNA was synthesized. Selected key genes included cycloartenol synthase (CAS), squalene synthase (SQS), and squalene monooxygenase (SMO). To verify the sequence of the genes, the amplified fragments of them were separately cloned into the pTG19-T vector and their targeted region were finally sequenced. After confirming the sequence of selected genes, the relative expression level of all of the target genes was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR) method. The results showed that the expression level of CAS in salicylic acid-treated plants did not change compared to control plants, however, expression levels of SQS and SMO were increased at some time courses. While, CAS, SQS and SMO expression levels in methyl-jasmonate treated plants were significantly increased in comparison with control plants. Considering the expression of the key genes in the biosynthesis pathway of diosgenin suggests that diosgenin is likely to increase in response to salicylic acid and in particular methyl jasmonate.