Indirect in vitro Regeneration of the Medicinal Plant, Aspilia africana, and Histological Assessment at Different Developmental Stages

Phenolic profiling and bioactivity assessment of in vitro propagated Psidium cattleianum Sabine: A promising study

Psidium cattleianum Sabine (strawberry guava) is an evergreen shrub that is grown as a fruiting hedge and has received significant consideration in the food and pharmaceutical disciplines. This study aims to set a promising protocol for in vitro propagation of P. cattleianum, along with profiling the phenolic content of the original plant (OP), induced callus (IC), and regenerated plantlets (RP) extracts, ultimately, evaluating their anti-inflammatory, antioxidant, and anticancer potential. Seeds were treated with commercial bleaching, HCl, and H2O2 to enhance the germination percentage and minimize the contamination percentage. Culturing sterilized leaf explants onto Murashige and Skoog (MS) medium supplemented with benzyl adenine (BA), 2,4-dichloro phenoxy acetic acid, and kinetin showed the best callus induction, while supplementation of MS media with BA, adenine sulfate, naphthalene acetic acid, and gibberellic acid activated regeneration. Augmentation of MS media with indol-3-butyric acid recorded the maximum rooting percentage. Finally, the obtained rooted shoots were successfully acclimatized in sand and peat moss soil. HPLC-MS/MS profiles of OP, RP, and IC showed a variety of phenolic metabolites. IC extract decreased the viability of MCF-7, HepG2, and K-562 cancer cell lines. Also, OP exhibits strong antioxidant activity. P. cattleianum and its RP are profound sources of phenolic compounds promoted for promising applications in the food and pharmaceutical industries.

Ploidy Status, Nuclear DNA Content and Start Codon Targeted (SCoT) Genetic Homogeneity Assessment in Digitalis purpurea L., Regenerated In Vitro

Digitalis purpurea L. is a therapeutically important plant that synthesizes important cardiotonics such as digitoxin and digoxin. The present work reports a detailed and efficient propagation protocol for D. purpurea by optimizing various PGR concentrations in Murashige and Skoog (MS) medium. The genetic homogeneity of in vitro regenerants was assessed by the flow cytometric method (FCM) and Start Codon Targeted (SCoT) marker technique. Firstly, the seeds inoculated in full MS medium added with 0.5 mg/L GA₃ produced seedlings. Different parts such as hypocotyl, nodes, leaves and apical shoots were used as explants. The compact calli were obtained on BAP alone or in combinations with 2, 4-D/NAA. The hypocotyl-derived callus induced somatic embryos which proliferated and germinated best in 0.75 mg/L BAP-fortified MS medium. Scanning electron microscopic (SEM) images confirmed the presence of various developmental stages of somatic embryos. Shoot regeneration was obtained in which BAP at 1.0 mg/L and 2.0 mg/L BAP + 0.5 mg/L 2,4-D proved to be the best treatments of PGRs in inducing direct and indirect shoot buds. The regenerated shoots showed the highest rooting percentage (87.5%) with 24.7 ± 1.9 numbers of roots/shoot in 1.0 mg/L IBA augmented medium. The rooted plantlets were acclimatized in a greenhouse at a survival rate of 85-90%. The genome size and the 2C nuclear DNA content of field-grown, somatic embryo-regenerated and organogenic-derived plants were estimated and noted to be 3.1, 3.2 and 3.0 picogram (pg), respectively; there is no alteration in ploidy status and the DNA content, validating genetic uniformity. Six SCoT primers unveiled 94.3%-95.13% monomorphic bands across all the plant samples analyzed, further indicating genetic stability among in vitro clones and mother plants. This study describes for the first time successful induction of somatic embryos from hypocotyl callus; and flow cytometry and SCoT marker confirmed the genetic homogeneity of regenerated plants.

Callus-Mediated High-Frequency Plant Regeneration, Phytochemical Profiling, Antioxidant Activity and Genetic Stability in Ruta chalepensis L

Efficient methods for callus induction and the high-frequency plant regeneration of Ruta chalepensis L. were established, and the phytochemical potential and antioxidant activity of a donor plant, ex-vitro-established micropropagated plants, and callus were also studied. Yellowish-green callus was induced with a frequency of 97.8% from internode shoot segments of the donor plant growing in soil in the botanical garden cultured on Murashige and Skoog (MS) medium containing 10 μM 2,4-D (2,4-dichlorophenoxyacetic acid) and 1 μM BA (6-benzyladenine). Adventitious shoots were regenerated from the yellowish-green callus on MS medium containing 5.0 μM (BA) and 1.0 μM 1-naphthaleneacetic acid (NAA), with a regeneration frequency of 98.4% and a maximum of 54.6 shoots with an average length of 4.5 cm after 8 weeks. The regenerated shoots were rooted in a medium containing 1.0 μM IBA (indole-3-butyric acid) and successfully transferred to ex vitro conditions in pots containing normal garden soil, with a 95% survival rate. The amounts of alkaloids, phenolics, flavonoids, tannins, and antioxidant activity of the ex-vitro-established micropropagated plants were higher than in the donor plant and callus. The highest contents of hesperidin and rutin (93.3 and 55.9 µg/mg, respectively) were found in the ex-vitro-established micropropagated plants compared to those obtained from the donor plant (91.4 and 31.0 µg/mg, respectively) and callus (59.1 and 21.6 µg/mg, respectively). The genetic uniformity of the ex-vitro-established micropropagated plants was appraised by the ISSR markers and compared with the donor plant. This is the first report describing the callus-mediated plant regeneration, as well as the production of phenolic compounds and antioxidant activities in R. chalepensis, which might be a potential alternative technique for the mass propagation and synthesis of bioactive compounds such as hesperidin and rutin.