In vitro propagation of Dianthus barbatus L. and cytokinin-mediated changes in its phenolic content and antioxidant capacity

Background Dianthus barbatus is a valuable ornamental and medicinal species with potential for the production of bioactive compounds, yet information on the integrated effects of plant growth regulators (PGRs) on its in vitro propagation and phytochemical responses remains limited. Thus, the effects of PGR treatments on in vitro seed germination, organogenesis, phytochemical profiles, and antioxidant responses of D. barbatus were evaluated. Results Surface-sterilized seeds for seedling establishment and seedling-derived nodal explants for shoot multiplication were cultured on Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP), thidiazuron (TDZ), or 6-(γ,γ-dimethylallylamino)purine riboside (2-iP) at 0.25, 0.5, and 1.0 mg L − 1 . The maximum seed germination rate (66.7%) was achieved with 0.25 mg L − 1 BAP. During axillary shoot multiplication, 0.25 mg L − 1 TDZ induced the highest shoot production (11.1 ± 1.3 per explant) and total leaf number (38.3 ± 2.3), whereas PGR-free MS medium produced the longest shoots (3.8 ± 0.9 cm). Multiplied shoots were rooted on MS medium with indole-3-acetic acid (IAA), 4-chlorophenoxyacetic acid (4-CPA), or α-naphthaleneacetic acid (NAA) at 0.25, 0.5, and 1.0 mg L − 1 . Rhizogenesis was most effective on PGR-free medium, yielding the highest root number​ (9.6 ± 0.9 per shoot), while 0.25 mg L − 1 IAA stimulated the longest root growth (4.2 ± 0.3 cm). Conversely, 4-CPA markedly suppressed root development. Rooted plants acclimatized ex vitro, achieving an 85% survival rate after 4 weeks in a peat-and-perlite mixture. Phytochemical analyses revealed that 0.25 mg L − 1 BAP promoted the highest mean total flavonoid content, condensed tannin content, and total antioxidant capacity, whereas 0.25 mg L − 1 TDZ elicited the highest mean total phenolic content in aerial parts of the plant. Conclusions These results demonstrate that cytokinin and auxin type and concentration differentially regulate D. barbatus development and phytochemical accumulation, providing an integrated basis for its in vitro culture and further evaluation of its bioactive potential.