An efficient transformation system for the medicinal plant Portulaca oleracea was established using agropine-type Agrobacterium rhizogenes ATCC15834. Hairy roots were obtained directly from cotyledon leaves explants seven days after inoculation with the bacteria. The highest transformation efficiency was obtained from cotyledon leaves explants, and amounted to 53.3% within two weeks. Roots grew rapidly on solid growth regulator free ½ Murashige and Skoog medium and demonstrated characteristics of transformed roots such as fast growth and high lateral branching. Successful and stable transfer of rolB gene was illustrated by PCR using specific primers of the gene. The hairy roots showed an ability to synthesize natural and medicinal product, dopamine. Elicitation of dopamine production in P. oleracea hairy roots was tested using different concentrations of methyl jasmonate (0, 100, 150, 200 μM) and salicylic acid (0, 125, 250, 500 μM), added to the hairy root cultures during the late growth phase. The results showed that the various concentrations of the methyl jasmonate significantly increased the dopamine content, but, at concentration of 100 μM, its impact was the most pronounced. Salicylic acid had no significant influence on dopamine production in hairy roots of P. oleracea
