Enhanced production of phenolic compounds in hairy root cultures of Polygonum multiflorum and its metabolite discrimination using HPLC and FT-IR methods

Abstract

Hairy root cultures (HRCs) are characterized by fast and unlimited root growth, and they have greater genetic stability than other cultivation methods. HRCs are known to accumulate phytochemical levels comparable to those of intact plant. In this study, HRCs of Polygonum multiflorum were established from leaf explants infected with Agrobacterium rhizogenes strain KCCM 11879. Over 60% of the explants showed hairy root induction after 21 days of cultivation on hormone-free MS (Murashige and Skoog Physiol Plant 15:473-479, 1962) medium; induced roots were confirmed by PCR using a rolC-specific primer. Of the six lines of HRCs selected for further analysis, line HR-01 performed best, producing a root biomass (105.2 g L-1 of FW, 9.7 g L-1 of DW), which is 10-fold higher than that of non-transgenic roots. The HR-01 line also showed a significant increase in its total phenolic content (26.64 mg g-1 DW), while non-transgenic roots accumulated 8.36 mg g-1 DW of total phenolic. The levels of phenolic compounds in the HRCs increased more than 2.5-fold following exposure to 50 μM methyl jasmonate for 5 days. Fourier transform infrared (FT-IR) spectroscopic analysis of bioactive accumulation in P. multiflorum enabled discrimination between hairy root and adventitious root cultures. Thus, it is evident from this study that HRCs could be an attractive proposition for large-scale production of root biomass and secondary metabolites of P. multiflorum in bioreactors.