Establishment of hairy root cultures of Rehmannia elata NE Brown ex Prain and production of iridoid and phenylethanoid glycosides

Hairy root lines were established through the infection of Agrobacterium rhizogenes strain (A4) from shoot tips and leaves of Rehmannia elmo N. E. Brown ex Prain (Orobanchaceae). Seven lines of hairy roots were selected on the basis of morphology and biomass increase in liquid Woody Plant Medium (WPM) supplemented with sucrose (30 g/L) without growth regulators. The transgenic status of the roots was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR) using rolB and rolC specific primers. After 30 days of growth the highest fresh weight (FW) and dry weight (DW) were determined in the S1 hairy root line (9.97 g/flask and 0.88 g/flask, respectively). UHPLC was then used to measure the accumulation of iridoid glycosides (aucubin, harpagide, harpagoside) and phenylethanoid glycosides (verbascoside and isoverbascoside) in selected hairy root lines. Among the iridoid glycosides, the highest amounts of aucubin (0.2 mg/g DW) and harpagide (1.57 mg/g DW) were detected in the S1 line, and harpagoside (0.09 mg/g DW) in the L14 line. Among the phenylethanoid glycosides, the highest levels of verbascoside (17.35 mg/g DW) and isoverbascoside ((similar to)2 mg/g DW) were identified in the S1 root line. Catalpol, catalposide and loganin could not be detected in any tested hairy root line.