Catharanthus roseus L. (G.) Don is the most widely studied plant because of its high pharmacological value. In vitro culture uses various plant parts such as leaves, nodes, internodes and roots for inducing callus and subsequent plant regeneration in C. roseus. However, till now, little work has been conducted on anther tissue using plant tissue culture techniques. Therefore, the aim of this work is to establish a protocol for in vitro induction of callus by utilizing anthers as explants in MS (Murashige and Skoog) medium fortified with different concentrations and combinations of PGRs. The best callusing medium contains high α-naphthalene acetic acid (NAA) and low kinetin (Kn) concentrations showing a callusing frequency of 86.6%. SEM–EDX analysis was carried out to compare the elemental distribution on the surfaces of anther and anther-derived calli, and the two were noted to be nearly identical in their elemental composition. Gas chromatography–mass spectrometry (GC–MS) analysis of methanol extracts of anther and anther-derived calli was conducted, which revealed the presence of a wide range of phytocompounds. Some of them are ajmalicine, vindolinine, coronaridine, squalene, pleiocarpamine, stigmasterol, etc. More importantly, about 17 compounds are exclusively present in anther-derived callus (not in anther) of Catharanthus. The ploidy status of anther-derived callus was examined via flow cytometry (FCM), and it was estimated to be 0.76 pg, showing the haploid nature of callus. The present work therefore represents an efficient way to produce high-value medicinal compounds from anther callus in a lesser period of time on a larger scale.

Tylophora indica (Burm. f.) Merrill is an endangered medicinal plant that possesses various active agents, such as tylophorinine, kaempferol, quercetin, α-amyrin and beta-sitosterol, with multiple medicinal benefits. α-amyrin, a triterpenoid, is widely known for its antimicrobial, anti-inflammatory, gastroprotective and hepatoprotective properties. In this study, we investigated the metabolite profiling of tissues and the effects of cadmium chloride and chitosan on in vitro accumulation of alkaloids in T. indica. First, the callus was induced from the leaf in 2,4-D-, NAA- and/or BAP-fortified MS medium. Subsequent shoot formation through organogenesis and in vitro roots was later induced. Gas chromatography–mass spectrometry (GC–MS)-based phytochemical profiling of methanolic extracts of in vivo and in vitro regenerated plants was conducted, revealing the presence of the important phytocompounds α-amyrin, lupeol, beta-sitosterol, septicine, tocopherol and several others. Different in vitro grown tissues, like callus, leaf and root, were elicited with cadmium chloride (0.1–0.4 mg L⁻¹) and chitosan (1–50 mg L⁻¹) to evaluate the effect of elicitation on α-amyrin accumulation, measured with high-performance thin layer chromatography (HPTLC). CdCl₂ and chitosan showed improved sugar (17.24 and 15.04 mg g⁻¹ FW, respectively), protein (10.76 and 9.99 mg g⁻¹ FW, respectively) and proline (7.46 and 7.12 mg g⁻¹ FW), especially at T3 (0.3 and 25 mg L⁻¹), in the leaf as compared to those of the control and other tissues. The antioxidant enzyme activities were also evaluated under an elicitated stress situation, wherein catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) displayed the highest activities in the leaf at T4 of both of the two elicitors. The α-amyrin yield was quantified with HPTLC in all tested tissues (leaf, callus and root) and had an Rf = 0.62 at 510 nm wavelength. Among all the concentrations tested, the T3 treatment (0.3 mg L⁻¹ of cadmium chloride and 25 mg L⁻¹ of chitosan) had the best influence on accumulation, irrespective of the tissues, with the maximum being in the leaf (2.72 and 2.64 μg g⁻¹ DW, respectively), followed by the callus and root. Therefore, these results suggest future opportunities of elicitors in scaling up the production of important secondary metabolites to meet the requirements of the pharmaceutical industry.

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.

Harsh climates, i.e., drought, extreme temperatures, and toxic gases, pose issues to agriculture by altering plants’ growth and yield. Biotechnology with biochemical defense approaches is beneficial for generating new plants/varieties with extra resilience to adverse conditions. In response to stress, cultures show an enriched level of secondary metabolite synthesis. Here, an efficient in vitro propagation method using axillary shoot proliferation, along with callus formation, was established in Glycyrrhiza glabra L. The phytochemical composition of in vitro and in vivo grown tissues was analyzed using a gas chromatography–mass spectrometry (GC–MS) technique, and the biochemical attributes were measured and compared in different investigated tissues. Callus formation from root explants was achieved with a frequency of 88.89% on MS medium containing 2.0 mg/L BAP and 0.5 mg/L 2,4-D. Axillary shoot proliferation was obtained from dormant buds when cultured onto MS supplemented with BAP alone, or in combination with, IAA. The maximum shoot proliferation (94.44%) was recorded on MS with 1.0 mg/L BAP with an average shoot length of 10.5 cm. The regenerated shoots were subcultured and transferred to the root induction medium, supplemented with various concentrations of IAA/IBA, wherein 2.0 mg/L IBA resulted in the best rooting frequency (88.89%). The GC–MS-based phytocompounds analysis of the methanolic extracts of root-derived callus and in vivo- and in vitro- grown root tissues was conducted. These samples revealed the presence of more than 35 therapeutically important bioactive compounds, such as methylglabridin, sitosterol, lupeol, squalene, stearic acid, linoleic acid, etc. The biochemical parameters, like total phenolic content, flavonoid content, DPPH scavenging activity, superoxide dismutase, and peroxidase activity were also measured. All the biochemical attributes were found to be higher in in vitro derived roots than the callus and in vivo grown root (donor) samples. These findings demonstrated that callus (root derived) and in vitro roots are a stable and potent source of multiple phytocompounds, encompassing medical significance with wide applications. This study may serve as an alternative opportunity in the sustained and continuous synthesis of important compounds without harming natural vegetation and normal environment.