Optimizing hairy root production from explants of Phyllanthus hainanensis, a shrub used for traditional herbal medicine

Phyllanthus hainanensis is a shrub that has been used in traditional herbal medicine. It has great pharmaceutical potential for treating diseases such as cancer and diabetes. As a prerequisite for propagation of this species on a large scale, hairy roots in P. hainanensis were induced using Rhizobium rhizogenes and various factors affecting hairy root induction and growth evaluated. Seven factors were tested: (1) type of explant, (2) type of culture medium, (3) duration of pre-culture, (4) R. rhizogenes inoculum cell density, (5) duration of infection, (6) acetosyringone concentration in the culture medium, and (7) duration of incubation. The optimal protocol for hairy root induction and growth was: young shoots, pre-cultured in Y1 for 2 d, inoculated with R. rhizogenes broth with an OD600 of 0.6 for 20 min, and incubated for 3 d. Putative transgenic hairy roots were initially identified by morphology and then confirmed by polymerase chain reaction. Successful and optimal production of hairy roots is a critical prerequisite for industrial scale clonal propagation of P. hainanensis. Being able to cultivate the plant on a large scale will provide rapid and ready supply of the plant materials that can be used in herbal medicine and in scientific and industrial exploitation.