Micropropagation of pokeweed (Phytolacca americana L.) and comparison of phenolic, flavonoid content, and antioxidant activity between pokeweed callus and other parts

Abstract

Background Pokeweed (Phytolacca americana L.) is regarded as an invasive plant in many parts of the world but possesses therapeutic characteristics used for antitumor and rheumatism treatment. This study investigated the effects of auxins and four explants on pokeweed callus induction. The effects of cytokinins and combinations between cytokinins and NAA on shoot and root induction were also studied. TPC, TFC and antioxidant activity of calli were screened and compared with other pokeweed plant parts. Methods Four explants were used to induce callus using 2,4-D and IBA at 1, 2, 3 and 4 mg/l for each auxin. Direct shoot organogenesis from nodal explants was investigated using BAP, kinetin and TDZ (1, 2 and 4 mg/l for each cytokinin). Combined effects between cytokinins and NAA at 0.1, 0.2 and 0.3 mg/l were further simultaneously estimated with root induction. Calli derived from the leaves were compared with other plant parts for TPC, TFC and antioxidant activity using the Folin-Ciocalteu, AlCl3 colorimetric assay and DPPH assays, respectively. Results Results showed that MS medium containing 2 mg/l 2,4-D induced callus formation on leaf explants that provided highest fresh and dry weights. Three types of synthetic cytokinins as kinetin, TDZ and BAP were used for direct shoot organogenesis from pokeweed nodes. MS medium containing 2 mg/l kinetin was effective in stimulating normal shoots, with the largest number of shoots and leaves and the longest shoots. The combination between cytokinins and NAA showed no positive effect on shoot and root induction from pokeweed nodal explants. For TPC and TFC determination, pokeweed seeds and leaves possessed the highest phenolic and flavonoid contents, respectively. Highest phenolic content of pokeweed seeds led to lowest IC50 by DPPH assay. Phenolic content was higher than flavonoid content. Conclusion Results suggested promising conditions for callus induction. Leaf explants cultured on MS medium with 2 mg/l 2,4-D and nodal explants cultured on MS medium with 2 mg/l kinetin provided the largest number of normal shoots and leaves. NAA did not show positive effects on shoot and root induction when combined with cytokinins. Chemical constituent screening indicated that seeds and leaves provided highest TPC and TFC, respectively, while pokeweed calli contained higher phenolic than flavonoid content. This is the first report describing chemical constituent screening and antioxidant activity of calli and other parts of the pokeweed plant. Results provided significant information to further enhance bioactive compound contents of pokeweed calli using elicitation methods.

The Optimization of Medium Conditions and Auxins in the Induction of Adventitious Roots of Pokeweed (Phytolacca americana L.) and Their Phytochemical Constituents

“…However, not all auxins have the ability to induce adventitious root development. Trunjaruen et al [ 34 ] compared the effects of IBA and 2,4-dichlorophenoxyacetic acid (2,4-D) on pokeweed micropropagation. Their results showed that pokeweed roots were not observed in 2,4-D treatments.…”

Vegetative propagation of Phytolacca acinosa Roxb. by rhizome cuttings: a step towards conservation and cultivation approach

“…Further, similar to our findings, cytokinins have been reported to increase the shoot length and leaf number in Phytolacca dodecandra (Chishimba et al, 1999). Kinetin also improved the shooting and leaf numbers in Phytolacca americana (Trunjaruen et al, 2022). The efficacy of applying cytokinins (kinetin) and GA 3 in promoting sprouting responses, root and shoot development among rhizome explants has been reported in several plant species, such as Pongamia pinnata (Sugla et al, 2007); Jurinea dolomiaea (Banday et al, 2014); Talinum triangulare (Swarna and Ravindhran, 2013); Picrorhiza kurroa (Patial et al, 2012) and Euphorbia wallichi (Hassan et al, 2020).…”