Influence of methyl jasmonate on expression patterns of polyketide synthase genes in Hypericum perforatum L.

St. John's wort (Hypericum perforatum L.) is a medicinal plant that is well known for its anti-depressant properties. Hypericin and hyperforin are the two active compounds that have the greatest medicinal value. Considering the importance of these compounds, it is necessary to have solutions to increase their production through biotechnology. Therefore, as preliminary study the expression of two key polyketide synthase genes including HpPKS2 and HpPKS1 in hypericin biosynthetic pathway was studied. Methyl jasmonate was used as elicitor to stimulate gene expression in concentrations of 0, 10 and 100 micromolar before flowering stage. Leaves and stems samples were then collected at 0, 12, 24 and 48 hours after MeJA treatment. The expression level of genes was examined by semi-quantitative RT-PCR method. The results showed that the expression level of both HpPKS2 and HpPKS1 genes were increased in leaf and stem tissues due to the application of MeJA, and at the concentrations of 10 and especially 100 µm, there was a significant difference with the control (0 concentration). Moreover, the expression level of both genes showed a rising trend in the time series of 0, 12, 24 and 48 hours after spraying MeJA in both tissues, and generally the greatest increase in expression was observed at 48 hours. The results of this study showed that both polyketide synthase genes are induced under the influence of methyl jasmonate and lead to their higher expression.