Specificity of Growth and Synthesis of Secondary Metabolites in Cultures in vitro Digitalis lanata Ehrh.

Rhizogenic, callus, and suspension cultures in vitro were obtained for Digitalis lanata and their growth, cytophysiological and biochemical characteristics were investigated. The obtained cultures were characterized by good growth characteristics (growth indexes I in the range of 5-13). Suspension cell culture had a specific growth rate mu within 0.2-0.3 days(-1) and it was characterized by a two-phase growth curve (growth retardation during the exponential phase). In the obtained cultures, a study of the qualitative and quantitative composition of secondary metabolites by UPLC-ESI-MS and HPLC-ESI-MS showed the absence of cardiac glycosides. At the same time, phenylethanoids and steroidal glycosides of the furostanol type were found in all studied cultures. The total content of phenylethanoids in callus and suspension cultures was approximately 0.5% of the dry biomass. Based on the results of mass spectrometry, ten phenylethanoid structures, including digiciliside A, digiciliside B, maxoside, purpureaside E, and their methyl derivatives and isomers, and also seven furostanol glycosides with aglycones tigogenin and gitogenin were identified. It has been shown that the composition of secondary metabolites depends on the degree of cell differentiation: furostanol glycosides were prevalent in a rhizogenic culture consisting mainly of differentiated cells, while the diversity of phenylethanoids significantly increases in callus and suspension cell cultures consisting of dedifferentiated cells. The results of the study confirm the hypothesis put forward in our previous works about the specificity of secondary metabolism and its high intensity in plant cell cultures.

Automated summary

This study investigated different in vitro cultures of Digitalis lanata, including rhizogenic, callus, and suspension cultures. It found that differentiated cells in the rhizogenic culture predominantly produced furostanol glycosides, while the callus and suspension cultures consisting of dedifferentiated cells showed increased diversity of phenylethanoids.