Improvement of phytochemical production by plant cells and organ culture and by genetic engineering

Eco-friendly approaches to phytochemical production: elicitation and beyond

Highly ameliorated phytochemicals from plants are recognized to have numerous beneficial effects on human health. However, obtaining secondary metabolites directly from wild plants is posing a great threat to endangered plant species due to their over exploitation. Moreover, due to complicated structure and stereospecificity chemical synthesis of these compounds is a troublesome procedure. As a result, sustainable and ecofriendly in vitro strategy has been adopted for phytochemicals production. But, lack of fully differentiated cells lowers down cultured cells productivity. Consequently, for enhancing yield of metabolites produced by cultured plant cells a variety of methodologies has been followed one such approach includes elicitation of culture medium that provoke stress responses in plants enhancing synthesis and storage of bioactive compounds. Nevertheless, for conclusive breakthrough in synthesizing bioactive compounds at commercial level in-depth knowledge regarding metabolic responses to elicitation in plant cell cultures is needed. However, technological advancement has led to development of molecular based approaches like metabolic engineering and synthetic biology which can serve as promising path for phytochemicals synthesis. This review article deals with classification, stimulating effect of elicitors on cultured cells, parameters of elicitors and action mechanism in plants, modern approaches like metabolic engineering for future advances.

Co-cultures from Plants and Cyanobacteria: A New Way for Production Systems in Agriculture and Bioprocess Engineering

Due to the global increase in the world population, it is not possible to ensure a sufficient food supply without additional nitrogen input into the soil. About 30-50% of agricultural yields are due to the use of chemical fertilizers in modern times. However, overfertilization threatens biodiversity, such as nitrogen-loving, fast-growing species overgrow others. The production of artificial fertilizers produces nitrogen oxides, which act as greenhouse gases. In addition, overfertilization of fields also releases ammonia, which damages surface waters through acidification and eutrophication. Diazotrophic cyanobacteria, which usually form a natural, stable biofilm, can fix nitrogen from the atmosphere and release it into the environment. Thus, they could provide an alternative to artificial fertilizers. In addition to this, biofilms stabilize soils and thus protect against soil erosion and desiccation. This chapter deals with the potential of cyanobacteria as the use of natural fertilizer is described. Possible partners such as plants and callus cells and the advantages of artificial co-cultivation will be discussed later. In addition, different cultivation systems for studying artificial co-cultures will be presented. Finally, the potential of artificial co-cultures in the agar industry will be discussed.

A review of Hydrocotyle bonariensis, a promising functional food and source of health-related phytochemicals

Hydrocotyle bonariensis is an edible herb, that is also used for traditional medical purposes. It is high in antioxidants, phenols, and flavonoids. However, there is limited information on the nutritional composition and the mechanisms by which nutritional and functional constituents of H. bonariensis affect human metabolism. With an aim to identify gaps in evidence to support the mainstream use of H. bonariensis for health and as a functional food, this review summarises current knowledge of the taxonomy, habitat characteristics, nutritional value and health-related benefits of H. bonariensis and its extracts. Ethno-medical practices for the plant are supported by pharmacological studies, yet animal model studies, clinical trials and food safety assessments are needed to support the promotion of H. bonariensis and its derivatives as superfoods and for use in the modern pharmaceutical industry.

Developments in biotechnological tools and techniques for production of reserpine

In the quest for novel medications, researchers have kept on studying nature to unearth beneficial plant species with medicinal qualities that may cure various diseases and disorders. These medicinal plants produce different bioactive secondary metabolites with immense therapeutic importance. One such valuable secondary metabolite, reserpine (C₃₃H₄₀N₂O₉), has been used for centuries to cure various ailments like hypertension, cardiovascular diseases, neurological diseases, breast cancer, and human promyelocytic leukaemia. Rauvolfia spp. (family Apocynaceae) is an essential reservoir of this reserpine. The current review thoroughly covers different non-conventional or in vitro-mediated biotechnological methods adopted for pilot-scale as well as large-scale production of reserpine from Rauvolfia spp., including techniques like multiple shoot culture, callus culture, cell suspension culture, precursor feeding, elicitation, synthetic seed production, scale-up via bioreactor, and hairy root culture. This review further analyses the unexplored and cutting-edge biotechnological tools and techniques to alleviate reserpine production. KEY POINTS: • Reserpine, a vital indole alkaloid from Rauvolfia spp., has been used for centuries to cure several ailments. • Overview of biosynthetic pathways and biotechnological applications for enhanced production of reserpine. • Probes the research gaps and proposes novel alternative techniques to meet the pharmaceutical industry's need for reserpine while reducing the over-exploitation of natural resources.

Tap the sap - investigation of latex-bearing plants in the search of potential anticancer biopharmaceuticals

Latex-bearing plants have been in the research spotlight for the past couple of decades. Since ancient times their extracts have been used in folk medicine to treat various illnesses. Currently they serve as promising candidates for cancer treatment. Up to date there have been several in vitro and in vivo studies related to the topic of cytotoxicity and anticancer activity of extracts from latex-bearing plants towards various cell types. The number of clinical studies still remains scarce, however, over the years the number is systematically increasing. To the best of our knowledge, the scientific community is still lacking in a recent review summarizing the research on the topic of cytotoxicity and anticancer activity of latex-bearing plant extracts. Therefore, the aim of this paper is to review the current knowledge on in vitro and in vivo studies, which focus on the cytotoxicity and anticancer activities of latex-bearing plants. The vast majority of the studies are in vitro, however, the interest in this topic has resulted in the substantial growth of the number of in vivo studies, leading to a promising number of plant species whose latex can potentially be tested in clinical trials. The paper is divided into sections, each of them focuses on specific latex-bearing plant family representatives and their potential anticancer activity, which in some instances is comparable to that induced by commonly used therapeutics currently available on the market. The cytotoxic effect of the plant's crude latex, its fractions or isolated compounds, is analyzed, along with a study of cell apoptosis, chromatin condensation, DNA damage, changes in gene regulation and morphology changes, which can be observed in cell post plant extract addition. The in vivo studies go beyond the molecular level by showing significant reduction of the tumor growth and volume in animal models. Additionally, we present data regarding plant-mediated biosynthesis of nanoparticles, which is regarded as a new branch in plant latex research. It is solely based on the green-synthesis approach, which presents an interesting alternative to chemical-based nanoparticle synthesis. We have analyzed the cytotoxic effect of these particles on cells. Data regarding the cytotoxicity of such particles raises their potential to be involved in the design of novel cancer therapies, which further underlines the significance of latex-bearing plants in biotechnology. Throughout the course of this review, we concluded that plant latex is a rich source of many compounds, which can be further investigated and applied in the design of anticancer pharmaceuticals. The molecules, to which this cytotoxic effect can be attributed, include alkaloids, flavonoids, tannins, terpenoids, proteases, nucleases and many novel compounds, which still remain to be characterized. They have been studied extensively in both in vitro and in vivo studies, which provide an excellent starting point for their rapid transfer to clinical studies in the near future. The comprehensive study of molecules from latex-bearing plants can result in finding a promising alternative to several pharmaceuticals on the market and help unravel the molecular mode of action of latex-based preparations.

Biogenic Synthesis of Copper-Based Nanomaterials Using Plant Extracts and Their Applications: Current and Future Directions

Plants have been used for multiple purposes over thousands of years in various applications such as traditional Chinese medicine and Ayurveda. More recently, the special properties of phytochemicals within plant extracts have spurred researchers to pursue interdisciplinary studies uniting nanotechnology and biotechnology. Plant-mediated green synthesis of nanomaterials utilises the phytochemicals in plant extracts to produce nanomaterials. Previous publications have demonstrated that diverse types of nanomaterials can be produced from extracts of numerous plant components. This review aims to cover in detail the use of plant extracts to produce copper (Cu)-based nanomaterials, along with their robust applications. The working principles of plant-mediated Cu-based nanomaterials in biomedical and environmental applications are also addressed. In addition, it discusses potential biotechnological solutions and new applications and research directions concerning plant-mediated Cu-based nanomaterials that are yet to be discovered so as to realise the full potential of the plant-mediated green synthesis of nanomaterials in industrial-scale production and wider applications. This review provides readers with comprehensive information, guidance, and future research directions concerning: (1) plant extraction, (2) plant-mediated synthesis of Cu-based nanomaterials, (3) the applications of plant-mediated Cu-based nanomaterials in biomedical and environmental remediation, and (4) future research directions in this area.

Gamma ray-induced tissue responses and improved secondary metabolites accumulation in Catharanthus roseus

The present study investigated the impact of gamma ray irradiation on callus biomass growth and the yield of vincristine and vinblastine of in vitro grown tissues of Catharanthus roseus. The biochemical alteration underlying the synthesis of secondary metabolites has also been studied and a comparison of yield was prepared. The embryogenic tissues were exposed to 20, 40, 60, 80, and 100 Gy gamma ray doses and the callus biomass fresh weight, the embryogenesis (the embryo numbers, germination, plant regeneration), the alteration of protein, proline, and sugar attributes at different morphogenetic stages were monitored. The callus biomass growth was maximum (1.65 g) in 20 Gy exposed tissues and was less in 100 Gy treatment (0.33 g). The gamma-irradiated embryogenic tissues differentiated into embryos but the embryogenesis % and somatic embryo number per culture reduced with increasing doses. It was least in 80 Gy where very low numbers of embryos were formed (3.45 and 3.30 mean torpedo and cotyledonary embryo numbers per callus mass, respectively) which later germinated into plantlets. Protein, proline, sugar, and different antioxidant enzymes, i.e., superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) activities, were investigated as the tissues were exposed to gamma ray elicitation/signaling, evoking cellular stress. Increased 80 Gy gamma dose inhibited a 42.73% decrease in protein accumulation at initiation stages of embryogenic tissue. Soluble sugar level also declined gradually being least in 80 Gy treated tissues (14.51 mg gm^-1 FW) compared to control (20.2 mg gm^-1 FW). Proline content, however, increased with increasing gamma doses, maximum at 80 Gy (8.28 mg gm^-1 FW). The SOD, APX, and CAT activity increased linearly with enhanced level of gamma doses and maximum, i.e., 3.91 EU min^-1 mg^-1, 1.71 EU min^-1 mg^-1, and 4.89 EU min^-1 mg^-1, protein activity was noted for SOD, APX, and CAT, respectively, at 80 Gy gamma rays treated tissues. The quantification of vinblastine and vincristine in gamma ray elicitated tissues was made by using high-pressure thin layer chromatography (HPTLC). Somatic embryo-regenerated plant's leaves had the maximum yield of vinblastine (15.13 µgm gm^-1 DW) at 40 Gy irradiation dose compared to control (13.30 µgm gm^-1 DW)-the increased yield % is 13.75. The stem is also rich source producing 11.98 µgm gm^-1 DW of vinblastine. Among the various developmental stages of embryos, vinblastine content was highest in germinating stage of embryos (10.14 µgm gm^-1 DW) compared to other three, i.e., initiation, proliferation, and maturation embryo stages. Similarly, highest accumulation of vincristine (6.32 µg gm^-1 DW) was noted at low gamma irradiation dose (20 Gy) in leaf tissues. The present study indicates that the synthesis of vinblastine and vincristine was growth- and development-specific and the lower 20-40 Gy gamma levels were more effective in enriching alkaloids while higher doses declined yield. KEY POINTS: • Vinblastine and vincristine yield was quantified in in vitro grown tissues and leaves of embryo regenerated Catharanthus roseus after gamma ray treatment. • The accumulation of vinblastine and vincristine was maximum in regenerated leaves; low doses were more efficient in improving yield. • Gamma ray irradiation impacted biochemical profiles, caused cellular stress, and perhaps responsible for improved alkaloid yield.

Micropropagation of Vaccinium corymbosum L.: An Alternative Procedure for the Production of Secondary Metabolites

In vitro culture has become a dependable approach for the mass production of plant material as the market for innovative plant-derived medicinal approaches has grown significantly. Furthermore, because it permits manipulation of biosynthetic routes to boost the production and accumulation of certain compounds, this technology has enormous potential for the manufacture of natural bioactive chemicals. As a result, the goal of this study was to develop an efficient micropropagation system for biomass production and to investigate the accumulation of bioactive compounds from Vaccinium corymbosum L., Duke and Hortblue Petite cultivars. Two in vitro plant tissue culture systems were used for shoots production: a solid medium (5 g/L Plant agar) and liquid medium (Plantform bioreactor). The culture medium used was Woddy Plant Medium (WPM) supplemented with two growth regulators: 0.5 mg/L and 1 mg/L zeatina (Z) and 5 mg/L N6-(2-Isopentenyl) adenine (2iP). The content of phenolic compounds, carotenoids, and chlorophylls of the in vitro shoot extracts were examined via the HPLC-DAD-MS/MS technique. The results showed that cv. Hortblue Petite produced a higher amount of biomass compared with cv. Duke, on all variants of culture media in both systems (solid and liquid), while the shoots extract of the Duke variety in the liquid culture system (under all concentrations of growth regulators) had the highest content of total phenolic compounds (16,665.61 ± 424.93 μg/g). In the case of the lipophilic compounds analysed (chlorophylls and carotenoids), the solid medium reported the highest values, whereas media supplemented with 0.5 mg/L Z was proved to have the richest total content for both cultivars.

Phytochemical Profiling and Assessment of Anticancer Activity of Leptocarpha rivularis Extracts Obtained from In Vitro Cultures

Plant cell culture is a source of plant material from which bioactive metabolites can be extracted. In this work, the in vitro propagation of Leptocarpha rivularis, an endemic Chilean shrub with anticancer activity, is described. Different media were tested and optimized for the introduction, propagation, and rooting steps of the micropropagation process. At the end of this process, 83% of plants were successfully acclimatized under greenhouse conditions. Callus induction from the internodal stem segment was performed using various combinations of phytohormones. Green-colored, friable, and non-organogenic callus was generated with a callus induction index higher than 90%. The chemical composition of extracts and callus, obtained from clonal plants, was assessed and the results indicate that the phytochemical profiles of extracts from micropropagated plants are like those found for plants collected from natural habitats, leptocarpine (LTC) being the major component. However, no LTC was detected in callus extract. HeLa and CoN cells, treated with LTC or extract of micropropagated plants, exhibit important diminution on cell viability and a drastic decrease in gene expression of IL-6 and mmp2, genes associated with carcinogenic activity. These effects are more important in cancer cells than in normal cells. Thus, micropropagated L. rivularis could be developed as a potential source of efficient antiproliferative agents.

Critical factors influencing in vitro propagation and modulation of important secondary metabolites in Withania somnifera (L.) dunal

Withania somnifera (L.) Dunal is a valuable medicinal plant in the Solanaceae family. It is commonly known as Ashwagandha and is widely distributed around the globe. It has multiple pharmacological properties owing to the existence of diverse secondary metabolites viz., withanolide A, withanolide D, withaferin A, and withanone. It is in great demand in the herbal industry because of its extensive use. In this background, the major challenge lies in the rapid multiplication of elite cultivars of W. somnifera in order to produce genetically and phytoconstituents uniform plant material for pharmaceutical industries. Thus it is necessary to explore various biotechnological approaches for the clonal mass propagation and synthesis of pharmaceutically important constituents in W. somnifera. Though there are several studies on in vitro propagation on W. somnifera, yet many factors that critically influence the in vitro response and withanolides production need to be fine-tuned in the pretext of the existing knowledge. The current review focuses on the advancements and prospects in biotechnological interventions to meet the worldwide demands for W. somnifera and its bioactive compounds. This update on in vitro studies on W. somnifera will be useful to many researchers, entrepreneurs, and herbal industries looking for its in vitro mass multiplication and scientific utilization.

Engineering Considerations to Produce Bioactive Compounds from Plant Cell Suspension Culture in Bioreactors

The large-scale production of plant-derived secondary metabolites (PDSM) in bioreactors to meet the increasing demand for bioactive compounds for the treatment and prevention of degenerative diseases is nowadays considered an engineering challenge due to the large number of operational factors that need to be considered during their design and scale-up. The plant cell suspension culture (CSC) has presented numerous benefits over other technologies, such as the conventional whole-plant extraction, not only for avoiding the overexploitation of plant species, but also for achieving better yields and having excellent scaling-up attributes. The selection of the bioreactor configuration depends on intrinsic cell culture properties and engineering considerations related to the effect of operating conditions on thermodynamics, kinetics, and transport phenomena, which together are essential for accomplishing the large-scale production of PDSM. To this end, this review, firstly, provides a comprehensive appraisement of PDSM, essentially those with demonstrated importance and utilization in pharmaceutical industries. Then, special attention is given to PDSM obtained out of CSC. Finally, engineering aspects related to the bioreactor configuration for CSC stating the effect of the operating conditions on kinetics and transport phenomena and, hence, on the cell viability and production of PDSM are presented accordingly. The engineering analysis of the reviewed bioreactor configurations for CSC will pave the way for future research focused on their scaling up, to produce high value-added PDSM.

Towards a Cardoon (Cynara cardunculus var. altilis)-Based Biorefinery: A Case Study of Improved Cell Cultures via Genetic Modulation of the Phenylpropanoid Pathway

Cultivated cardoon (Cynara cardunculus var. altilis L.) is a promising candidate species for the development of plant cell cultures suitable for large-scale biomass production and recovery of nutraceuticals. We set up a protocol for Agrobacterium tumefaciens-mediated transformation, which can be used for the improvement of cardoon cell cultures in a frame of biorefinery. As high lignin content determines lower saccharification yields for the biomass, we opted for a biotechnological approach, with the purpose of reducing lignin content; we generated transgenic lines overexpressing the Arabidopsis thaliana MYB4 transcription factor, a known repressor of lignin/flavonoid biosynthesis. Here, we report a comprehensive characterization, including metabolic and transcriptomic analyses of AtMYB4 overexpression cardoon lines, in comparison to wild type, underlining favorable traits for their use in biorefinery. Among these, the improved accessibility of the lignocellulosic biomass to degrading enzymes due to depletion of lignin content, the unexpected increased growth rates, and the valuable nutraceutical profiles, in particular for hydroxycinnamic/caffeoylquinic and fatty acids profiles.

Turning Waste into Beneficial Resource: Implication of Ageratum conyzoides L. in Sustainable Agriculture, Environment and Biopharma Sectors

The annual herb, Ageratum conyzoides L. (Asteraceae), is distributed throughout the world. Although invasive, it can be very useful as a source of essential oils, pharmaceuticals, biopesticides, and bioenergy. However, very limited information exists on the molecular basis of its different utility as previous investigations were mainly focused on phytochemical/biological activity profiling. Here we have explored various properties of A. conyzoides that may offer environmental, ecological, agricultural, and health benefits. As this aromatic plant harbors many important secondary metabolites that may have various implications, biotechnological interventions such as genomics, metabolomics and tissue-culture can be indispensable tools for their mass-production. Further, A. conyzoides acts as a natural reservoir of begomoviruses affecting a wide range of plant species. As the mechanisms of disease spreading and crop infection are not fully clear, whole-genome sequencing and various advanced molecular technologies including RNAi, CRISPER/Cas9, multi-omics approaches, etc., may aid to decipher the molecular mechanism of such disease development and thus, can be useful in crop protection. Overall, improved knowledge of A. conyzoides is not only essential for developing sustainable weed control strategy but can also offer potential ways for biomedicinal, environment, safe and clean agriculture applications.

Morphological and Chemical Diversity and Antioxidant Capacity of the Service Tree (Sorbus domestica L.) Fruits from Two Eco-Geographical Regions

Service tree, Sorbus domestica L., is a rare and neglected wild fruit tree species of southern and central Europe. Being distributed in different eco-geographical regions, with fragmented and low-density populations, S. domestica represents an interesting model case for investigating patterns of within- and between-population diversity at geographical and environmental scales. This study aimed to analyze the proximate composition, antioxidant activity, and morphometric fruit characteristics. We examined the diversity and population divergences of 49 S. domestica individuals originating from seven populations across continental and Mediterranean eco-geographical regions. In addition, tests of isolation by distance and environment were performed to detect the magnitude of divergence explained by geographic and environmental variables. Significant differences between the studied populations were found in almost all of the studied morphometric and chemical fruit characteristics. The studied service tree populations were characterized by high phenotypic variation despite the low number of trees per population. Model-based population structure analysis using morphometric and chemical fruit characteristics revealed three groups of service tree populations. We concluded that non-effective pollen and seed dispersal along with genetic drift and specific environmental factors resulted in a distinct phenotype with a specific chemical composition in the isolated island population. In addition, a pattern of isolation by the environment was revealed. We infer that morphological and chemical differences between the studied populations in the true service tree from different eco-geographical regions were mediated by adaptation to the specific environmental conditions.

Anti-Inflammatory Effects of Weigela subsessilis Callus Extract via Suppression of MAPK and NF-κB Signaling

Weigela subsessilis is used in folk medicine to treat pain and allergic syndromes in Korea. However, the antibacterial and anti-inflammatory activities of W. subsessilis callus extract remain unexplored. In this study, we aimed to evaluate the W. subsessilis callus of pharmacological activity. Therefore, we first established in vitro calluses of W.subsessilis via plant tissue culture methods. We then evaluated the antioxidant and anti-inflammatory effects of W. subsessilis callus extract in lipopolysaccharide (LPS)-treated RAW264.7 macrophage cells. The W. subsessilis callus extract showed antioxidant and anti-inflammatory effects. These effects were regulated via suppression of mitogen-activated protein kinase signaling through LPS-induced translocation of nuclear factor kappa B (NF-κB) p65 from the cytoplasm to the nucleus. W. subsessilis callus extract also showed antibacterial and anti-inflammatory activities in Propionibacterium acnes-treated HaCaT keratinocyte cells. These results indicate that W. subsessilis callus extract has antioxidant, antibacterial and anti-inflammatory activities, suggesting its possible application in the treatment of inflammatory disorders.

Efficient plant regeneration from embryogenic cell suspension cultures of Euonymus alatus

To establish an efficient plant regeneration system from cell suspension cultures of Euonymus alatus, embryogenic callus formation from immature embryos was investigated. The highest frequency of embryogenic callus formation reached 50% when the immature zygotic embryos were incubated on Murashige and Skoog (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D). At higher concentrations of 2,4-D (over 2 mg/L), the frequency of embryogenic callus formation declined significantly. The total number of somatic embryos development was highest with the 3% (w/v) sucrose treatment, which was found to be the optimal concentration for somatic embryo formation. Activated charcoal (AC) and 6-benzyladenine (BA) significantly increased the frequency of plantlet conversion from somatic embryos, but gibberellic acid (GA₃) had a negative effect on plantlet conversion and subsequent development from somatic embryos. Even though the cell suspension cultures were maintained for more than 1 year, cell aggregates from embryogenic cell suspension cultures were successfully converted into normal somatic embryos with two cotyledons. To our knowledge, this is the first successful report of a plant regeneration system of E. alatus via somatic embryogenesis. Thus, the embryogenic cell line and plant regeneration system established in this study can be applied to mass proliferation and production of pharmaceutical metabolite in E. alatus.

Plant synthetic biology for producing potent phyto-antimicrobials to combat antimicrobial resistance

Inappropriate and injudicious use of antimicrobial drugs in human health, hygiene, agriculture, animal husbandry and food industries has contributed significantly to rapid emergence and persistence of antimicrobial resistance (AMR), one of the serious global public health threats. The crisis of AMR versus slower discovery of newer antibiotics put forth a daunting task to control these drug-resistant superbugs. Several phyto-antimicrobials have been identified in recent years with direct-killing (bactericidal) and/or drug-resistance reversal (re-sensitization of AMR phenotypes) potencies. Phyto-antimicrobials may hold the key in combating AMR owing to their abilities to target major microbial drug-resistance determinants including cell membrane, drug-efflux pumps, cell communication and biofilms. However, limited distribution, low intracellular concentrations, eco-geographical variations, beside other considerations like dynamic environments, climate change and over-exploitation of plant-resources are major blockades in full potential exploration phyto-antimicrobials. Synthetic biology (SynBio) strategies integrating metabolic engineering, RNA-interference, genome editing/engineering and/or systems biology approaches using plant chassis (as engineerable platforms) offer prospective tools for production of phyto-antimicrobials. With expanding SynBio toolkit, successful attempts towards introduction of entire gene cluster, reconstituting the metabolic pathway or transferring an entire metabolic (or synthetic) pathway into heterologous plant systems highlight the potential of this field. Through this perspective review, we are presenting herein the current situation and options for addressing AMR, emphasizing on the significance of phyto-antimicrobials in this apparently post-antibiotic era, and effective use of plant chassis for phyto-antimicrobial production at industrial scales along with major SynBio tools and useful databases. Current knowledge, recent success stories, associated challenges and prospects of translational success are also discussed.

Food ingredients and food made with plant cell and tissue cultures: State-of-the art and future trends

Climate change and an increasing world population means traditional farming methods may not be able to meet the anticipated growth in food demands. Therefore, alternative agricultural strategies should be considered. Here, plant cell and tissue cultures (PCTCs) may present a possible solution, as they allow for controlled, closed and sustainable manufacturing of extracts which have been or are still being used as colorants or health food ingredients today. In this review we would like to highlight developments and the latest trends concerning commercial PCTC extracts and their use as food ingredients or even as food. The commercialization of PCTC-derived products, however, requires not only regulatory approval, but also outstanding product properties or/and a high product titer. If these challenges can be met, PCTCs will become increasingly important for the food sector in coming years.

Biotechnological strategies for the sustainable production of diosgenin from Dioscorea spp

Diosgenin is a plant-derived secondary metabolite mainly present in the members of the plant family Dioscoreaceae. It is a pharmaceutically important compound because of its anti-cancerous, anti-diabetic, anticoagulant, anti-thrombosis, anti-inflammatory, anti-viral, anti-ageing and other properties. Biotechnology provides an opportunity to genetically manipulate cells, tissues, organs or the whole organisms by propagating them in vitro in order to harvest the bioactive compounds. Diosgenin production from botanical sources is being improved by in vitro techniques which include elicitation, genetic transformations and bioconversions. Various techniques have been developed to obtain compounds for drug detection including separation from plants and other natural sources, molecular modelling, synthetic chemistry and combinatorial chemistry. Development in molecular markers determines genetic relationship, genetic linkage map construction, genetic diversity and identification. For rapid clonal propagation and ex situ conservation, the in vitro tools involving plant cell, tissue and organ culture have been well documented for plant-derived diosgenin production. The present review encompasses the wide application of the biotechnological techniques for diosgenin production via elucidating its biosynthetic pathway, in vitro production and mass propagation and elicitation. In addition, molecular marker-mediated diversity assessment of diosgenin containing plant species is also discussed. The review also presents the recent literature to explore the limitations of the relevant studies and future direction of research on production of diosgenin from Dioscorea spp. KEY POINTS: • Critical and updated assessment on sustainable production of diosgenin from Dioscorea spp. • In vitro propagation of Dioscorea spp. and elicitation of diosgenin production. • Diversity assessment of Dioscorea spp. using molecular markers.

Powerful Plant Antioxidants: A New Biosustainable Approach to the Production of Rosmarinic Acid

Modern lifestyle factors, such as physical inactivity, obesity, smoking, and exposure to environmental pollution, induce excessive generation of free radicals and reactive oxygen species (ROS) in the body. These by-products of oxygen metabolism play a key role in the development of various human diseases such as cancer, diabetes, heart failure, brain damage, muscle problems, premature aging, eye injuries, and a weakened immune system. Synthetic and natural antioxidants, which act as free radical scavengers, are widely used in the food and beverage industries. The toxicity and carcinogenic effects of some synthetic antioxidants have generated interest in natural alternatives, especially plant-derived polyphenols (e.g., phenolic acids, flavonoids, stilbenes, tannins, coumarins, lignins, lignans, quinines, curcuminoids, chalcones, and essential oil terpenoids). This review focuses on the well-known phenolic antioxidant rosmarinic acid (RA), an ester of caffeic acid and (R)-(+)-3-(3,4-dihydroxyphenyl) lactic acid, describing its wide distribution in thirty-nine plant families and the potential productivity of plant sources. A botanical and phytochemical description is provided of a new rich source of RA, Satureja khuzistanica Jamzad (Lamiaceae). Recently reported approaches to the biotechnological production of RA are summarized, highlighting the establishment of cell suspension cultures of S. khuzistanica as an RA chemical biofactory.

Genetic and epigenetic dynamics affecting anthocyanin biosynthesis in potato cell culture

Anthocyanins are antioxidant pigments widely used in drugs and food preparations. Flesh-coloured tubers of the cultivated potato Solanum tuberosum are important sources of different anthocyanins. Due to the high degree of decoration achieved by acylation, anthocyanins from potato are very stable and suitable for the food processing industry. The use of cell culture allows to extract anthocyanins on-demand, avoiding seasonality and consequences associated with land-based-tuber production. However, a well-known limit of cell culture is the metabolic instability and loss of anthocyanin production during successive subcultures. To get a general picture of mechanisms responsible for this instability, we explored both genetic and epigenetic regulation that may affect anthocyanin production in cell culture. We selected two clonally related populations of anthocyanin-producing (purple) and non-producing (white) potato cells. Through targeted molecular investigations, we identified and functionally characterized an R3-MYB, here named StMYBATV. This transcription factor can interact with bHLHs belonging to the MBW (R2R3-MYB, bHLH and WD40) anthocyanin activator complex and, potentially, may interfere with its formation. Genome methylation analysis revealed that, for several genomic loci, anthocyanin-producing cells were more methylated than clonally related white cells. In particular, we localized some methylation events in ribosomal protein-coding genes. Overall, our study explores novel molecular aspects associated with loss of anthocyanins in cell culture systems.

Salycilic Acid Induces Exudation of Crocin and Phenolics in Saffron Suspension-Cultured Cells

The production of crocin, an uncommon and valuable apocarotenoid with strong biological activity, was obtained in a cell suspension culture of saffron (Crocus sativus L.) established from style-derived calli to obtain an in-vitro system for metabolite production. Salycilic acid (SA) was used at different concentrations to elicit metabolite production, and its effect was analyzed after a 4 days of treatment. HPLC-DAD analysis was used for total crocin quantification while the Folin-Ciocâlteu method was applied for phenolic compounds (PC) content. Interestingly, despite cell growth inhibition, a considerable exudation was observed when the highest SA concentration was applied, leading to a 7-fold enhanced production of crocin and a 4-fold increase of phenolics compared to mock cells. The maximum antioxidant activity of cell extracts was evidenced after SA 0.1 mM elicitation. Water-soluble extracts of saffron cells at concentrations of 1, 0.5, and 0.1 µg mL⁻¹ showed significant inhibitory effects on MDA-MB-231 cancer cell viability. The heterologous vacuolar markers RFP-SYP51, GFPgl133Chi, and AleuRFP, were transiently expressed in protoplasts derived from the saffron cell suspensions, revealing that SA application caused a rapid stress effect, leading to cell death. Cell suspension elicitation with SA on the 7th day of the cell growth cycle and 24 h harvest time was optimized to exploit these cells for the highest increase of metabolite production in saffron cells.

Transgenesis as a Tool for the Efficient Production of Selected Secondary Metabolites from in Vitro Plant Cultures

The plant kingdom abounds in countless species with potential medical uses. Many of them contain valuable secondary metabolites belonging to different classes and demonstrating anticancer, anti-inflammatory, antioxidant, antimicrobial or antidiabetic properties. Many of these metabolites, e.g., paclitaxel, vinblastine, betulinic acid, chlorogenic acid or ferrulic acid, have potential applications in medicine. Additionally, these compounds have many therapeutic and health-promoting properties. The growing demand for these plant secondary metabolites forces the use of new green biotechnology tools to create new, more productive in vitro transgenic plant cultures. These procedures have yielded many promising results, and transgenic cultures have been found to be safe, efficient and cost-effective sources of valuable secondary metabolites for medicine and industry. This review focuses on the use of various in vitro plant culture systems for the production of secondary metabolites.

Antiaging, Stress Resistance, and Neuroprotective Efficacies of Cleistocalyx nervosum var. paniala Fruit Extracts Using Caenorhabditis elegans Model

Plant parts and their bioactive compounds are widely used by mankind for their health benefits. Cleistocalyx nervosum var. paniala is one berry fruit, native to Thailand, known to exhibit various health benefits in vitro. The present study was focused on analyzing the antiaging, stress resistance, and neuroprotective effects of C. nervosum in model system Caenorhabditis elegans using physiological assays, fluorescent imaging, and qPCR analysis. The results suggest that the fruit extract was able to significantly extend the median and maximum lifespan of the nematode. It could also extend the healthspan by reducing the accumulation of the “age pigment” lipofuscin, inside the nematode along with regulating the expression of col-19, egl-8, egl-30, dgk-1, and goa-1 genes. Further, the extracts upregulated the expression of daf-16 while downregulating the expression of daf-2 and age-1 in wild-type nematodes. Interestingly, it could extend the lifespan in DAF-16 mutants suggesting that the extension of lifespan and healthspan was dependent and independent of DAF-16-mediated pathway. The fruit extract was also observed to reduce the level of Reactive Oxygen Species (ROS) inside the nematode during oxidative stress. The qPCR analysis suggests the involvement of skn-1 and sir-2.1 in initiating stress resistance by activating the antioxidant mechanism. Additionally, the fruit could also elicit neuroprotection as it could extend the median and maximum lifespan of transgenic strain integrated with Aβ. SKN-1 could play a pivotal role in establishing the antiaging, stress resistance, and neuroprotective effect of C. nervosum. Overall, C. nervosum can be used as a nutraceutical in the food industry which could offer potential health benefits.