Coleus forskohlii: advancements and prospects of in vitro biotechnology

High-frequency shoot regeneration, assessment of genetic fidelity, and histochemical analysis of forskolin production in Coleus forskohlii Briq

Forskolin, a diterpenoid found in the roots of Coleus forskohlii, has generated significant interest in the medical field due to its various therapeutic uses. This study aimed to establish an effective system for regenerating C. forskohlii plants, ensuring a year-round supply of plant material and forskolin production. We tested different concentrations of cytokinins, either alone or combined with auxin, to see their impact on shoot multiplication and growth. We found that a medium supplemented with 1.5 mg L-1 of meta-topolin (mT) resulted in the highest number of shoots (~ 12.66) and leaves (~ 20) within about 5 days. When mT (1 mg L-1) was combined with a low amount of auxin (0.05 mg L-1 NAA), we obtained an even greater number of leaves (~ 23). The shoot regeneration capacity was consistent over five subculture passages, showing minimal variation in mean shoot length and number. During acclimatization, around 91% of the plantlets grown in vermiculite + sand survived. The photosynthetic pigment concentration in the plantlets modestly increased in the first 10 days and reached its highest level after 30 days. Genetic fidelity assays using inter simple sequence repeats (ISSRs) confirmed the similarity between the in vitro derived plantlets and the mother plant. Micro-morphological features of in vitro and ex-vitro acclimated plantlets also matched those of the mother plant, further confirming genetic accuracy. Histochemical staining with vanillin confirmed the presence of forskolin in the in vitro roots, indicated by the violet coloration in the cells. Forskolin quantification was also validated by HPLC where in vitro derived roots were documented to undergo an almost ~ 1.8-fold in comparison to that of the mother plant. This established protocol can effectively address resource scarcity for commercial-scale forskolin production and sustainable conservation techniques.

An update on biotechnological intervention mediated by plant tissue culture to boost secondary metabolite production in medicinal and aromatic plants

Since prehistoric times, medicinal and aromatic plants (MAPs) have been employed for various therapeutic purposes due to their varied array of pharmaceutically relevant bioactive compounds, i.e. secondary metabolites. However, when secondary metabolites are isolated directly from MAPs, there is occasionally very poor yield and limited synthesis of secondary metabolites from particular tissues and certain developmental stages. Moreover, many MAPs species are in danger of extinction, especially those used in pharmaceuticals, as their natural populations are under pressure from overharvesting due to the excess demand for plant-based herbal remedies. The extensive use of these metabolites in a number of industrial and pharmaceutical industries has prompted a call for more research into increasing the output via optimization of large-scale production using plant tissue culture techniques. The potential of plant cells as sources of secondary metabolites can be exploited through a combination of product recovery technology research, targeted metabolite production, and in vitro culture establishment. The plant tissue culture approach provides low-cost, sustainable, continuous, and viable secondary metabolite production that is not affected by geographic or climatic factors. This study covers recent advancements in the induction of medicinally relevant metabolites, as well as the conservation and propagation of plants by advanced tissue culture technologies.

A forskolin-mediated increase in cAMP promotes T helper cell differentiation into the Th1 and Th2 subsets rather than into the Th17 subset

The adenylyl cyclase (AC) signaling pathway is suggested to be a key regulator of immune system functions. However, specific effects of cyclic adenosine monophosphate (cAMP) on T helper (Th) cell differentiation and functions are unclear. The involvement of cAMP in the Th cell differentiation program, in particular the development of Th1, Th2, and Th17 subsets, was evaluated employing forskolin (FSK), a labdane diterpene well known as an AC activator. FSK mediated an elevation in Th1-specific markers reinforcing the Th1 cell phenotype. The Th2 differentiation was supported by FSK, though cell metabolism was negatively affected. In contrast, the Th17 immunophenotype was severely suppressed leading to the highly specific upregulation of CXCL13. The causality between FSK-elicited cAMP production and the observed reinforcement of Th2 differentiation was established by using AC inhibitor 2',5'-dideoxyadenosine, which reverted the FSK effects. Overall, an FSK-mediated cAMP increase affects Th1, Th2 and Th17 differentiation and can contribute to the identification of novel therapeutic targets for the treatment of Th cell-related pathological processes.

Liver organoid culture methods

Organoids, three-dimensional structures cultured in vitro, can recapitulate the microenvironment, complex architecture, and cellular functions of in vivo organs or tissues. In recent decades, liver organoids have been developed rapidly, and their applications in biomedicine, such as drug screening, disease modeling, and regenerative medicine, have been widely recognized. However, the lack of repeatability and consistency, including the lack of standardized culture conditions, has been a major obstacle to the development and clinical application of liver organoids. It is time-consuming for researchers to identify an appropriate medium component scheme, and the usage of some ingredients remains controversial. In this review, we summarized and compared different methods for liver organoid cultivation that have been published in recent years, focusing on controversial medium components and discussing their advantages and drawbacks. We aimed to provide an effective reference for the development and standardization of liver organoid cultivation.

Advancements and prospectives of sugar beet (Beta vulgaris L.) biotechnology

Sugar beet (Beta vulgaris L.) is the second largest sugar-producing crop (following sugarcane), accounting around 40% of total global sugar output. It has been reckoned with huge contribution in sugar, ethanol, and fodder industries. Since sugar beet is recalcitrant in nature, to address the multifaceted difficulties associated with its conventional propagation, several biotechnological tools and techniques aiming with in vitro-based mass regeneration-cum-genetic enhancement are becoming popular. The implementation of effective methodology for in vitro regeneration from ex vitro explant sources becomes the necessity for successful commercial-scale clonal propagation and genetic modification. Substantial research achievements have been made in the past few decades in connection to the optimization of in vitro protocols for direct and callus-mediated regeneration, homozygous line production, somatic hybridization, and genetic transformation of sugar beet. The current review summarizes several reported findings on various physio-chemical factors responsible for direct, indirect organogenesis, somatic embryogenesis, protoplast culture, haploid culture, acclimatization accountable for plantlet mass multiplication, assessing the genetic integrity of in vitro-cultured plantlets, and, finally, successful transgenic approaches to remediate biotic and abiotic stresses. Furthermore, this study highlights undiscovered regions, research gaps, and major bottlenecks that might be considered in developing significant innovative ideas related to sugar beet biotechnology in the near future. KEY POINTS: • Sugar beet, the second largest sugar producer, is a major contributor in sugar, ethanol, and fodder industries. • Current review comprehensively evaluates diverse factors influencing the success of in vitro biotechnological interventions. • This review further highlights the research gaps and offers way outs to attain comprehensive genetic improvement.

Silver nanoparticle synthesis and their potency against multidrug-resistant bacteria: a green approach from tissue-cultured Coleus forskohlii

Drug resistance is a major concern nowadays, and finding alternatives of the well-known antibiotic is necessary. Green nanoparticles are emerging as a tenable alternative to this with a large spectrum of activity. The present manuscript describes an eco-friendly approach for green synthesis of silver nanoparticles from both in vitro and in vivo leaf extract of Coleus forskohlii. Leaf extracts were used in synthesis of nanoparticles which were further analyzed through UV-Vis, dynamic light scattering, energy-dispersive spectroscopy, and transmission electron microscopy. Antimicrobial activity of silver nanoparticles alone, as well as crude extract of the plant itself, was carried out against eight multidrug-resistant respiratory tract infecting pathogenic strains. Satisfactory antimicrobial activities were found with nanoparticles, in vitro and in vivo leaf extracts. However, gradually higher to lower inhibition potential against pathogenic bacterial strains was found in silver nanoparticles, in vitro and in vivo leaf extracts. Seven bioactive compounds were detected in the crude extract through gas chromatography-mass spectroscopy analysis. Results revealed that nanoparticle formation occurred in a wide range of sizes (10-50 nm) and shapes (trigonal, hexagonal, spherical, rod). The diversity in size and shape of the nanoparticles makes them biologically active. Silver nanoparticle exhibits significantly better antimicrobial activities as compared to the plant extract in case of nearly all pathogens with a maximum zone of inhibition of 15.33 ± 0.94 mm where more than 12 well-known antibiotics failed to respond. Because of this broad-spectrum activity of nanoparticles as well as the leaf extracts against life-threatening microbes, it can be used as future generation drugs.

Use of polylactic acid microvessel to obtain microplantlets of Eucalyptus microcorys through indirect organogenesis

Microplants of Eucalyptus microcorys were produced through indirect organogenesis, and the interaction of plant growth regulators (PGRs) (TDZ-thidiazuron and NAA-α-naphthalene acetic acid), juvenile tissues (cotyledon and hypocotyl) and different types of polylactic acid (PLA) microvessels on plant production were evaluated. Cotyledon-derived callus induction increased by 30-60% in all tested combinations of TDZ and NAA concentrations compared the absence of PGRs. Hypocotyl-derived callus induction was improved in most tested combinations of TDZ and NAA concentrations. Moreover, 100% callus induction from both tissues was achieved with TDZ (1, 2 and 3 mg L^-1) + NAA (0 mg L^-1). Bud induction from cotyledon tissues was improved with TDZ (1 and 3 mg L^-1) + NAA (0 mg L^-1) and from hypocotyl with TDZ (1 and 2 mg L^-1) + NAA (0 mg L^-1). Shoot elongation from cotyledon tissues was not improved from any combination of PGRs, whereas TDZ (1 mg L^-1) + NAA (0 mg L^-1), TDZ (1 mg L^-1) + NAA (4 mg L^-1), TDZ (2 mg L^-1) + NAA (4 mg L^-1) and TDZ (3 mg L^-1) + NAA (2 mg L^-1) improved shoot elongation from hypocotyl tissues. Adventitious rooting and acclimatization of microcuttings ranged from 40 to 70% in three of the tested microvessels. The acclimatized microcuttings had low genetic variability. Successful production of E. microcorys microplants was achieved in this study using hypocotyl tissue and cultivated a culture medium supplemented with TDZ and NAA, using PLA-based microvessels.

Advances in biotechnology of Emblica officinalis Gaertn. syn. Phyllanthus emblica L.: a nutraceuticals-rich fruit tree with multifaceted ethnomedicinal uses

Emblica officinalis Gaertn. syn. Phyllanthus emblica L., universally known as ‘Amla’ or ‘Aonla’ or ‘Indian gooseberry’, is a popular fruit tree belonging to the family Euphorbiaceae and order Geraniales. It is said to be the very first tree that originated on earth, as claimed by age-old Indian mythology. Almost all parts of the tree i.e., root, bark, leaf, flower, fruit and seed are utilized in Ayurvedic and Unani medicinal formulations to improve the overall digestive process, decrease fever, act as a blood purifier, relieve asthma and cough, improve heart health, etc. This tree contains major secondary metabolites like emblicanin-A and emblicanin-B, and also is an affluent source of vitamin-C. Additionally, some other secondary metabolites like tannins, gallic acid, pyrogallol, and pectin are also present in significant amounts. Conventional propagation has been improved via suitable interventions of agrotechnology both in production and protection areas. However, the rate of propagation remains slower; therefore, attempts have been made for biotechnological advancements on E. officinalis. The present review makes an attempt to highlight the botanical description, geographical distribution, ethnopharmacological importance, conventional propagation and protection of this medicinal tree, describing the in vitro-based plant organ and tissue culture methods like direct and indirect organogenesis and somatic embryogenesis along with interventions of molecular marker-based biotechnology and nanotechnology. Further, the prospect of the yet-to-be-explored biotechnological methods for secondary metabolite enhancement like cell suspension, protoplast culture, genetic transformation, etc. and their potential for enhanced emblicanin production have also been discussed in this appraisal.

Hairy root culture technology: applications, constraints and prospect

Hairy root (HR) culture, a successful biotechnology combining in vitro tissue culture with recombinant DNA machinery, is intended for the genetic improvement of plants. This technology has been put to use since the last three decades for genetic advancement of medicinal and aromatic plants and also to harvest the economical products in the form of secondary metabolites that are significantly important for their ethnobotanical and pharmacological properties. It also provides an efficient way out for the quicker extraction and quantification of the valuable phytochemicals. The current review provides an account of the in vitro HR culture technology and its wide-scale applications in the field of research as well as in pharmaceutical industries. Different facets of HR with respect to the culture establishment, phytochemical production as well as research investigations concerning the areas of gene manipulation, biotransformation of the secondary metabolites, phytoremediation, their industrial utilisations and different problems encountered during the application of this technology have been covered in this appraisal. Eventually, an idea has been provided on HR about the recent trends on the progress of this technology that may open up newer prospects in near future and calls for further research and explorations in this field. KEY POINTS: • Genetic engineering-based HR culture aims towards enhanced secondary metabolite production. • This review explores an insight in the HR technology and its multi-faceted approaches. • Up-to-date ground-breaking research applications and constraints of HR culture are discussed.

Indian sarsaparilla, Hemidesmus indicus (L.) R. Br. ex Schult: tissue culture studies

Hemidesmus indicus (L.) R. Br. ex Schult is commonly known as anantmul or Indian sarsaparilla. The roots of this plant, which display a wide range of medicinal, biological, and phytopharmaceutical properties, are used in the pharmaceutical and food industries. Conventionally, the plant is propagated by seed germination or vegetatively, but the efficacy of traditional methods has some limitations: plants derived from seed germination are prone to seed-borne diseases, or plantlet production using vegetative propagation is limited. In contrast, plant tissue culture allows for large-scale propagation and secondary metabolite production in vitro without sacrificing plants from their natural habitats. Many efforts have been made over 40 years of research to establish efficient micropropagation protocols to speed up cultivation of this plant, including callus-mediated in vitro propagation, somatic embryogenesis, and shoot multiplication using cotyledenory nodes, stem segments, shoot tips, and nodal explants. Among these explants, nodal explants are the most commonly used for H. indicus micropropagation. The application of adenine sulfate, citric acid, ascorbic acid, and arginine may be useful in preventing explant browning, premature leaf senescence, and shoot tip abscission during in vitro culture. This review provides insight into micropropagation, use of synthetic seeds for short-term germplasm preservation, and in vitro production of secondary metabolites such as 2-hydroxy-4-methoxybenzaldehyde, lupeol, vanillin, and rutin, from in vitro root and callus cultures. Furthermore, unexplored and possible innovative areas of research in Hemidesmus biotechnology are also discussed. KEY POINTS: • Hemidesmus indicus has multiple therapeutic applications. • H. indicus roots are used in confectionary and pharmacy. • This review comprehensively assesses H. indicus tissue culture. • Challenges and future research of H. indicus biotechnology are discussed.

Biotechnological advancements in Catharanthus roseus (L.) G. Don

Catharanthus roseus (L.) G. Don, also known as Madagascar periwinkle or Sadabahar, is a herbaceous plant belonging to the family Apocynaceae. Being a reservoir for more than 200 alkaloids, it reserves a place for itself in the list of important medicinal plants. Secondary metabolites are present in its leaves (e.g., vindoline, vinblastine, catharanthine, and vincristine) as well as basal stem and roots (e.g., ajmalicine, reserpine, serpentine, horhammericine, tabersonine, leurosine, catharanthine, lochnerine, and vindoline). Two of its alkaloids, vincristine and vinblastine (possessing anticancerous properties), are being used copiously in pharmaceutical industries. Till date, arrays of reports are available on in vitro biotechnological improvements of C. roseus. The present review article concentrates chiefly on various biotechnological advancements based on plant tissue culture techniques of the last three decades, for instance, regeneration via direct and indirect organogenesis, somatic embryogenesis, secondary metabolite production, synthetic seed production, clonal fidelity assessment, polyploidization, genetic transformation, and nanotechnology. It also portrays the importance of various factors influencing the success of in vitro biotechnological interventions in Catharanthus and further addresses several shortcomings that can be further explored to create a platform for upcoming innovative approaches. KEY POINTS: • C. roseus yields anticancerous vincristine and vinblastine used in pharma industry. •In vitro biotechnological interventions prompted major genetic advancements. • This review provides an insight on in vitro-based research achievements till date. • Key bottlenecks and prospective research methodologies have been identified herein.

Biotechnological Interventions for Ginsenosides Production

Ginsenosides are secondary metabolites that belong to the triterpenoid or saponin group. These occupy a unique place in the pharmaceutical sector, associated with the manufacturing of medicines and dietary supplements. These valuable secondary metabolites are predominantly used for the treatment of nervous and cardiac ailments. The conventional approaches for ginsenoside extraction are time-consuming and not feasible, and thus it has paved the way for the development of various biotechnological approaches, which would ameliorate the production and extraction process. This review delineates the biotechnological tools, such as conventional tissue culture, cell suspension culture, protoplast culture, polyploidy, in vitro mutagenesis, hairy root culture, that have been largely implemented for the enhanced production of ginsenosides. The use of bioreactors to scale up ginsenoside yield is also presented. The main aim of this review is to address the unexplored aspects and limitations of these biotechnological tools, so that a platform for the utilization of novel approaches can be established to further increase the production of ginsenosides in the near future.