Agrobacterium rhizogenes-mediated hairy root induction and plant regeneration from transgenic roots in Ficus carica L.

Abstract

One of the most effective biotechnological techniques for producing plant metabolites is the hairy roots (HRs) culture system. HRs are genetically and biologically stable and able to produce secondary metabolites in a short time. Ficus carica L. is one of the most important plant sources of valuable medicinal compounds, especially polyphenolic compounds. The aim of this study was to investigate the growth and morphological features of HRs, methyl jasmonate (MeJA) elicitation and plant regeneration potential of HRs induced by different strains of Agrobacterium rhizogenes on Ficus carica cv. Siah. Four bacterial strains (A4, A7, A13 and ATCC 15834) were used for HR induction in leaf and shoot samples. The MS medium containing 2 mg/l of 2,4-D in combination with 1 mg/l of TDZ or BAP was used to induce callus from HRs, and then the callus regeneration ability was evaluated in MS medium containing TDZ and NAA. Depending on explant type and bacterial strain, the roots were induced directly or indirectly (via callus formation) from the wound sites, and exhibited different morphology. The HRs showed high levels of phenolic compounds. A 4-day elicitation with MeJA, in dependence on the concentration, enhanced the phenolic capacity and antioxidant capacity of HRs. The calli obtained from HRs showed root (70-80%) and bud (23.33%) regeneration potential. The current study described that the HR culture systems, in addition to providing the possibility of plant regeneration from transgenic roots, could be a promising in vitro technique for high production of secondary metabolites through elicitation.