Hardening of Plantlets Regenerated from Transgenic Hairy Roots of Panax vietnamensis on Medium Containing Iron Nanoparticles

In this chapter, efficient hairy root induction and plant regeneration derived from hairy roots via the somatic embryogenesis system of Panax vietnamensis have been developed. The hairy roots derived from the infection of P. vietnamensis callus with A. rhizogenes strain ATCC 15834 were cultured on solid SH (Schenk and Hildebrandt 1972) medium supplemented with 2.0 mg/L benzyl adenine (BA), 0.5 mg/L α-naphthaleneacetic acid (NAA), and 30 g/L sucrose to induce callus formation for 6 weeks. Somatic embryos were obtained from hairy root-derived calli cultured on solid SH medium containing 2.0 mg/L BA and 1.0 mg/L 2.4-dichlorophenoxyacetic acid (2.4-D). These embryos developed into shoots when transferred to the plant growth regulator-free SH medium. The morphology of hairy roots-derived plantlets (Ri plant) was similar to control plantlets; however, it had more lateral roots. In addition, the role of iron nanoparticles on growth and biomass accumulation in plants is also discussed in this chapter. Adding iron nanoparticles (5.6 mg/L) to the culture medium had improved the in vitro rhizome proliferation as well as the growth of plantlets derived from the hairy roots of P. vietnamensis. However, the mechanisms underlying this effect still need to be well understood, so more studies are needed concerning plant’s development when exposed to iron nanoparticles.