Effect of iron oxide nanoparticles on hairy root induction and antioxidant activity in Purslane (Portulaca oleracea)

Many secondary metabolites produced by plants are used in manufacturing drugs and new treatments, but are too difficult, expensive or impossible to prepared by chemical synthesis. Biotechnology progresses have provided a huge source of new chemical compounds of plant origin to various applications. Purslane (Portulaca oleracea L.) is one of the valuable medicinal plants that World Health Organization (WHO) called it Global Panacea. Hairy root induction by Agrobacterium rhizogenes is an effective method for production of secondary metabolites.

In this study, hairy roots of Purslane were produced using Agrobacterium rhizogenes strains A4 and ATCC15834. The presence of the rolB gene in the hairy roots was confirmed by PCR using rolB gene specific primers. The effect of the type of strain (A4 and ATCC15834), explant (cotyledon, hypocotyl and seedling) and also different concentrations of Iron oxide nanoparticles (0, 20, 40 and 6 mg l-1) were examined as abiotic elicitors on the hairy root induction, growth and increase of secondary metabolites of hairy roots.  

The results showed that the highest hairy root induction (80 percent) was observed in the A4 strain, seedling explants and 40 mg l-1 the iron oxide nanoparticles. The greatest hairy root length was obtained by 60 mg l-1 the iron oxide nanoparticles (4.17 cm) and also ATCC15834 strain, seedling explants and 40 mg l-1 the iron oxide nanoparticles were superior for highest phenolic and flavonoid content (4.92 and 0.48 mg g DW) and also 2,2-diphenyl-1-picrylhydrazyl (52.59%) and ferric reducing antioxidant power (60.37(Mol g-1 DW)). Hairy root lines showed significant differences in growth rate and biomass production and the largest biomass production was exhibited by G line.

Overall, the strain and explant types and iron oxide nanoparticles had considerable effects on the hairy roots induction secondary metabolites production. The results indicated significant increases in hairy root induction and medicinal compounds by A4 and ATCC15834 strains, seedling explant and 40 mg l-1 the iron oxide nanoparticles.