Efficient In Vitro Propagation of Turpinia arguta and Quantitative Analysis of Its Ligustroflavone and Rhoifolin Content

Abstract

Turpinia arguta is an excellent medicinal plant mainly used for the treatment of pharyngitis, tonsillitis, and tonsillar abscesses. However, an efficient regeneration protocol using tissue cultures for T. arguta does not exist. Its main medicinal constituents are flavonoids, particularly ligustroflavone and rhoifolin. Here, we aimed to establish a tissue culture system for T. arguta for the first time using annual stem segments with axillary buds harvested from the field of the Jiangxi Academy of Forestry as explants by dynamically determining the accumulation of effective functional components in the tissue culture plantlets. Orthogonal tests were conducted to compare the effects of different explant disinfection times, media, and exogenous hormone ratios on the induction of the axillary bud growth, successional proliferation, and rooting of T. arguta stem segments. The best explant disinfection effect was achieved by disinfecting the T. arguta explant with 75% ethanol for 50 s, followed by 0.1% mercuric chloride (HgCl2) for 6 min, and the optimal media for successional proliferation and rooting were Murashige and Skoog (MS) + 0.2 mg/L of 6-benzyladenine (6-BA), + 0.03 mg/L of naphthaleneacetic acid (NAA), and ½ MS + 2.5 mg/L of indole-3-butyric acid + 0.5 mg/L of NAA, respectively. The detection of ligustroflavone and rhoifolin in tissue culture plantlets 0, 3, and 5 months after transplanting showed a significant increasing trend and eventually exceeded the content requirements of the 2020 Edition ofChinese Pharmacopoeia for T. arguta. Our findings provide, for the first time, an effective tissue culture system for T. arguta, thereby providing important information to support the germplasm preservation, innovation, and application of T. arguta in the future.