Shoot regeneration of stinging nettle (Urtica dioica L.), genetic stability, and content of bioactive compounds

The stinging nettle (Urtica dioica L.) is a well-known species with promising applications in the food, feed, pharmaceutical, textile, and cosmetic industries. Despite its great potential, there are very few reports on its micropropagation. This study aimed to develop an in vitro protocol for plantlet production, assess genomic integrity in regenerants, and evaluate major bioactive compound content using chromatographic methods. Two in vitro protocols were developed using shoot tips and nodal segments. The highest multiplication rate (2.0–2.4 shoots per explant) was recorded for nodal segments taken from in vitro-grown plants on media supplemented with 6-benzyloaminopurin (BAP; 3.0–5.0 mg/L) and thidiazuron (TDZ; 0.25–1.0 mg/L). The responses of the juvenile explants (shoot tips and nodal segments) were compared. Shoot tips were almost twice as effective as nodal segments in shoot induction (2.63 vs. 1.77) on the medium with TDZ. The genetic stability of U. dioica micropropagated plants during long-term culture was evaluated using inter-simple sequence repeat (ISSR) molecular markers for the first time. There were no somaclonal variations among plants derived from shoot-tip culture. Additionally, the effect of cytokinins on the genetic stability of microshoots was tested. Microshoots formed on the medium with BAP exhibited lower polymorphism (14.6%) than those formed on the medium with TDZ (26.9%). Phytochemical analyses revealed scopoletin in the roots and chlorogenic and caffeoylmalic acids in the leaves of plants grown in vitro for the first time. These results may be useful for future research and applications in the breeding and biotechnology of U. dioica. Two in vitro protocols were developed using shoot tips and nodal segments. The high genetic stability of micropropagated plants during long-term culture was confirmed using ISSR markers.