Comparative evaluation of culture systems for shoot propagation and phytochemical characteristics in pokeweed ( Phytolacca americana L.)

Background Phytolacca americana L. (pokeweed) is a medicinal plant containing diverse bioactive compounds, including phenolics, flavonoids, and saponins. Variation in phytochemical accumulation and concerns associated with harvesting from natural populations highlight the need for controlled and sustainable propagation systems. This study compared solid, liquid, and temporary immersion system (TIS) cultures of P. americana nodal explants containing axillary buds and evaluated their effects on plant growth and phytochemical characteristics. Methods Nodal explants were cultured on solid and liquid media or in a TIS bioreactor. Six TIS regimes combining 5 or 10 min immersion durations with 1, 2, or 3 immersions per day were evaluated. Growth, callus formation, biomass, total phenolic content (TPC), total flavonoid content (TFC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity were determined. Multivariate analyses were used to characterize treatment responses. Results All treatments showed 100% explant survival and response. Liquid culture produced the weakest shoot and leaf development, whereas TIS generally supported greater shoot growth. T6 (10 min, three immersions/day) produced the highest shoot length (5.69 ± 0.83 cm), leaf length (4.79 ± 0.55 cm), and dry weight (0.12 ± 0.03 g). T5 produced the highest TPC (14.82 ± 0.10 mg gallic acid equivalents per gram (GAE/g) extract), solid culture the highest TFC (31.25 ± 0.94 mg quercetin equivalents per gram (QE/g) extract), and T1 the strongest DPPH radical-scavenging activity (IC 50 = 553.25 ± 16.46 µg/mL). Multivariate analyses revealed distinct response patterns among culture systems and identified key traits contributing to treatment discrimination. Conclusion Culture system and immersion regime differentially influenced the growth and phytochemical characteristics of P. americana nodal explants. TIS, particularly T4–T6, showed potential for enhancing shoot development and biomass accumulation, providing a basis for further optimization of P. americana propagation and phytochemical production.