Elicitation of dopamine biosynthesis in common purslane as affected by methyl jasmonate and silicon

Common purslane that is a natural source of antioxidants, phenols, flavonoids, and dopamine possesses the potential to be used as a medicinal vegetable. The amount of active compounds in purslane is naturally low, so elicitation of plant response to produce more secondary metabolites may be important. In order to increase the amount of medicinal substances of the common purslane, foliar application and fertilization of silicon (each of them in two concentrations: 1 and 2 mM) alongside with methyl jasmonate spray (0, 75 and 150 µM) were applied. Measurement of silicon showed that the highest amount of leaf silicon was seen in 1 mM silicon spray regardless of methyl jasmonate treatments. Spraying of silicon without methyl jasmonate (Ss1M0) increased the leaf weight, grain yield, total phenol and leaf flavonoid content. Measurement of dopamine using high-performance liquid chromatography showed that fertilization of 1 mM silicon (Sf1M0) in the treatment group increased dopamine up to 2.5 folds in comparison with the control group. Also, silicon fertilization increased photosynthetic pigments and phosphorus concentration of leaves. To conclude, silicon can be used as an elicitor for increasing the amount of dopamine because its effect on dopamine biosynthesis was significantly more than methyl jasmonate that is a general elicitor. The effects of silicon on other medicinal substances of common purslane can be another avenue for further research.