Plant cell cultures as heterologous bio-factories for secondary metabolite production

Elicitor-mediated simultaneous accumulation of phloridzin and ursolic acid in Annurca apple peel-derived calli

BACKGROUND

Apple peel is rich in natural molecules, many exhibiting a significant bioactivity. In this study, our objective was to establish a novel callus line derived from the apple peel of the Italian local variety Annurca, known to accumulate high levels of dihydrochalcones and terpenes. In this regard, we tested the impact of one elicitor, yeast extract, on the expression of genes encoding key enzymes involved in phloridzin and ursolic acid biosynthesis, leading to the accumulation of these antioxidant compounds. We also assessed the bioactivity of callus extracts enriched in these phytochemicals.

RESULTS

After the elicitation, data showed increased expression of genes directly related to the synthesis of phloridzin and ursolic acid that were found to accumulate within the cultures. This presumably could explain the remarkable activity of extracts from the elicited-calli in inhibiting the growth of Staphylococcus aureus and Bacillus cereus. Also, the extracts enriched in antioxidant compounds inhibited reactive oxygen species (ROS) production in human cells exposed to ultraviolet-A (UV-A) radiation.

CONCLUSION

Our results underscore the vast potential of the Annurca apple peel cell line in producing natural compounds that can be employed as food components to promote human health. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A potyvirus provides an efficient viral vector for gene expression and functional studies in Asteraceae plants

Plant virus-derived vectors are rapid and cost-effective for protein expression and gene functional studies in plants, particularly for species that are difficult to genetically transform. However, few efficient viral vectors are available for functional studies in Asteraceae plants. Here, we identified a potyvirus named zinnia mild mottle virus (ZiMMV) from common zinnia (Zinnia elegans Jacq.) through next-generation sequencing. Using a yeast homologous recombination strategy, we established a full-length infectious cDNA clone of ZiMMV under the control of the cauliflower mosaic virus 35S promoter. Furthermore, we developed an efficient expression vector based on ZiMMV for the persistent and abundant expression of foreign proteins in the leaf, stem, root, and flower tissues with mild symptoms during viral infection in common zinnia. We showed that the ZiMMV-based vector can express ZeMYB9, which encodes a transcript factor inducing dark red speckles in leaves and flowers. Additionally, the expression of a gibberellic acid (GA) biosynthesis gene from the ZiMMV vector substantially accelerated plant height growth, offering a rapid and cost-effective method. In summary, our work provides a powerful tool for gene expression, functional studies, and genetic improvement of horticultural traits in Asteraceae plant hosts.

Influence of Primary Light Exposure on the Morphophysiological Characteristics and Phenolic Compounds Accumulation of a Tea Callus Culture (Camellia sinensis L.)

Tea plant calli (Camellia sinensis L.) are characterized by the accumulation of various phenolic compounds (PC)-substances with high antioxidant activity. However, there is still no clarity on the response of tea cells to light exposure of varying intensity. The purpose of the research was to study tea callus cultures grown under the influence of primary exposure to different light intensities (50, 75, and 100 µmol·m-2·s-1). The cultures' growth, morphology, content of malondialdehyde and photosynthetic pigments (chlorophyll a and b), accumulation of various PC, including phenylpropanoids and flavanols, and the composition of catechins were analyzed. Primary exposure to different light intensities led to the formation of chloroplasts in tea calli, which was more pronounced at 100 µmol·m-2·s-1. Significant similarity in the growth dynamics of cultures, accumulation of pigments, and content of malondialdehyde and various phenolics in tea calli grown at light intensities of 50 and 75 µmol·m-2·s-1 has been established, which is not typical for calli grown at 100 µmol·m-2·s-1. According to data collected using high-performance liquid chromatography, (+)-catechin, (-)-epicatechin, epigallocatechin, gallocatechin gallate, epicatechin gallate, and epigallocatechin gallate were the main components of the tea callus culture's phenolic complex. Its content changed under the influence of primary exposure to light, reaching the greatest accumulation in the final stages of growth, and depended on the light intensity. The data obtained indicate changes in the morphophysiological and biochemical characteristics of tea callus cultures, including the accumulation of PC and their individual representatives under primary exposure to light exposure of varying intensity, which is most pronounced at its highest values (100 µmol·m-2·s-1).

In vivo assembly in tobacco cells to elucidate and engineer the biosynthesis of 4-hydroxydihydrocinnamaldehyde from Gloriosa superba

KEY MESSAGE

This study described the biosynthesis of 4-hydroxydihydrocinnamaldehyde sharing with monolignol pathway and supplemented the biosynthesis of colchicine in G. superba, 4-hydroxydihydrocinnamaldehyde produced in tobacco BY2 cells provided an important stepstone. The precursor, 4-hydroxydihydrocinnamaldehyde (4-HDCA), participates in the biosynthesis of the carbon skeleton of colchicine, which is derived from L-phenylalanine. However, one hypothesis proposed that 4-HDCA is synthesized by sharing the early part of the monolignol pathway in G. superba. In this study, we validated this prediction and identified the enzymatic functions involved in this pathway. GsDBR1 is a crucial enzyme to illustrate 4-HDCA diverging from monolignol pathway, we first confirmed its reductase activity on 4-coumaraldehyde, an important intermediate compound in monolignol biosynthesis. Then, the biochemical function of recombinant enzymes belonging to the other four families were verified to elucidate the entire process of 4-HDCA biosynthesis from L-phenylalanine. After reconstruction, the 4-HDCA was 78.4 ng/g with fresh weight (FW) of transgenic tobacco cells, and the yield increased to 168.22 ng/g·FW after improved treatment with methyl jasmonate (MeJA). The elucidation of 4-HDCA biosynthesis sharing the monolignol pathway supplemented the biosynthesis of colchicine in G. superba, and the production of 4-HDCA in tobacco cells provides an important step in the development of plant cell cultures as heterologous bio-factories for secondary metabolite production.

Integration of induction, system optimization and genetic transformation in Veratrum californicum var. vitro cultures to enhance the production of cyclopamine and veratramine

Cyclopamine, a compound found in wild Veratrum has shown promising potential as a lead anti-cancer drug by effectively blocking cancer signaling pathways. However, its complex chemical structure poses challenges for artificial synthesis, thus limiting its supply and downstream drug production. This study comprehensively utilizes induction, system optimization, and transgenic technologies to establish an efficient suspension culture system for the high-yield production of cyclopamine and its precursor, veratramine. Experimental results demonstrate that methyl jasmonate (MeJA) effectively promotes the content of veratramine and cyclopamine in Veratrum californicum var. callus tissue, while yeast extract (YE) addition significantly increases cell biomass. The total content of veratramine and cyclopamine reached 0.0638 mg after synergistic treatment of suspension system with these two elicitors. And the content of the two substances was further increased to 0.0827 mg after the optimization by response surface methodology. Subsequently, a genetic transformation system for V. californicum callus was established and a crucial enzyme gene VnOSC1, involved in the steroidal alkaloid biosynthesis pathway, was screened and identified for genetic transformation. Combined suspension culture and synergistic induction system, the total content of the two substances in transgenic suspension system was further increased to 0.1228 mg, representing a 276.69% improvement compared to the initial culture system. This study proposes a complete and effective genetic transformation and cultivation scheme for V. californicum tissue cells, achieving milligram-level production of the anticancer agent cyclopamine and its direct precursor veratramine for the first time. It provides a theoretical basis for the industrial-scale production of these substances.

Enhancing Withanolide Production in the Withania Species: Advances in In Vitro Culture and Synthetic Biology Approaches

Withanolides are naturally occurring steroidal lactones found in certain species of the Withania genus, especially Withania somnifera (commonly known as Ashwagandha). These compounds have gained considerable attention due to their wide range of therapeutic properties and potential applications in modern medicine. To meet the rapidly growing demand for withanolides, innovative approaches such as in vitro culture techniques and synthetic biology offer promising solutions. In recent years, synthetic biology has enabled the production of engineered withanolides using heterologous systems, such as yeast and bacteria. Additionally, in vitro methods like cell suspension culture and hairy root culture have been employed to enhance withanolide production. Nevertheless, one of the primary obstacles to increasing the production of withanolides using these techniques has been the intricacy of the biosynthetic pathways for withanolides. The present article examines new developments in withanolide production through in vitro culture. A comprehensive summary of viable traditional methods for producing withanolide is also provided. The development of withanolide production in heterologous systems is examined and emphasized. The use of machine learning as a potent tool to model and improve the bioprocesses involved in the generation of withanolide is then discussed. In addition, the control and modification of the withanolide biosynthesis pathway by metabolic engineering mediated by CRISPR are discussed.

Genetically encoded Boolean logic operators to sense and integrate phenylpropanoid metabolite levels in plants

Synthetic biology has the potential to revolutionize biotechnology, public health, and agriculture. Recent studies have shown the enormous potential of plants as chassis for synthetic biology applications. However, tools to precisely manipulate metabolic pathways for bioproduction in plants are still needed. We used bacterial allosteric transcription factors (aTFs) that control gene expression in a ligand-specific manner and tested their ability to repress semi-synthetic promoters in plants. We also tested the modulation of their repression activity in response to specific plant metabolites, especially phenylpropanoid-related molecules. Using these aTFs, we also designed synthetic genetic circuits capable of computing Boolean logic operations. Three aTFs, CouR, FapR, and TtgR, achieved c. 95% repression of their respective target promoters. For TtgR, a sixfold de-repression could be triggered by inducing its ligand accumulation, showing its use as biosensor. Moreover, we designed synthetic genetic circuits that use AND, NAND, IMPLY, and NIMPLY Boolean logic operations and integrate metabolite levels as input to the circuit. We showed that biosensors can be implemented in plants to detect phenylpropanoid-related metabolites and activate a genetic circuit that follows a predefined logic, demonstrating their potential as tools for exerting control over plant metabolic pathways and facilitating the bioproduction of natural products.

Enhancement of specialized metabolites using CRISPR/Cas gene editing technology in medicinal plants

Plants are the richest source of specialized metabolites. The specialized metabolites offer a variety of physiological benefits and many adaptive evolutionary advantages and frequently linked to plant defense mechanisms. Medicinal plants are a vital source of nutrition and active pharmaceutical agents. The production of valuable specialized metabolites and bioactive compounds has increased with the improvement of transgenic techniques like gene silencing and gene overexpression. These techniques are beneficial for decreasing production costs and increasing nutritional value. Utilizing biotechnological applications to enhance specialized metabolites in medicinal plants needs characterization and identification of genes within an elucidated pathway. The breakthrough and advancement of CRISPR/Cas-based gene editing in improving the production of specific metabolites in medicinal plants have gained significant importance in contemporary times. This article imparts a comprehensive recapitulation of the latest advancements made in the implementation of CRISPR-gene editing techniques for the purpose of augmenting specific metabolites in medicinal plants. We also provide further insights and perspectives for improving metabolic engineering scenarios in medicinal plants.

Plant Heterotrophic Cultures: No Food, No Growth

Plant cells are capable of uptaking exogenous organic substances. This inherited trait allows the development of heterotrophic cell cultures in various plants. The most common of them are Nicotiana tabacum and Arabidopsis thaliana. Plant cells are widely used in academic studies and as factories for valuable substance production. The repertoire of compounds supporting the heterotrophic growth of plant cells is limited. The best growth of cultures is ensured by oligosaccharides and their cleavage products. Primarily, these are sucrose, raffinose, glucose and fructose. Other molecules such as glycerol, carbonic acids, starch, and mannitol have the ability to support growth occasionally, or in combination with another substrate. Culture growth is accompanied by processes of specialization, such as elongation growth. This determines the pattern of the carbon budget. Culture ageing is closely linked to substrate depletion, changes in medium composition, and cell physiological rearrangements. A lack of substrate leads to starvation, which results in a decrease in physiological activity and the mobilization of resources, and finally in the loss of viability. The cause of the instability of cultivated cells may be the non-optimal metabolism under cultural conditions or the insufficiency of internal regulation.

Highly Efficient Verbascoside Production from Olive (Olea europea L. var. Cellina di Nardò) In Vitro Cell Cultures

Olive (Olea europea L.) is one of the oldest and most important fruit tree species cultivated in the Mediterranean region. Various plant tissues, drupes, and olive oil contain several phenolics (including verbascoside, although it is present in the plant at a low level) that are well-known for their highly beneficial effects on human health. An in vitro olive cell suspension culture (cultivar Cellina di Nardò, "CdN") was established, characterized for its growth and morphological features. Furthermore, a vital and relatively uniform population of protoplasts was generated from the olive suspension culture to investigate their cellular characteristics during growth. The polyphenolic extract of the in vitro "CdN" olive cells contained almost exclusively verbascoside, as revealed by the UPLC-ESI-MS analysis. The content of verbascoside reached up to 100 mg/g DW, with an average production rate of approximately 50 mg/g DW over one year of culture. This level of production has not been previously reported in a limited number of previous studies. This remarkable production of verbascoside was associated with an exceptionally high antioxidant capacity. The high level of verbascoside production and purity of the extract make this system a promising tool for secondary metabolite production.

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.

Plant Tissue Culture and Metabolite Profiling for High-Value Natural Product Synthesis

The engineering of plant cell cultures to produce high-value natural products is suggested to be a safe, low-cost, and environmentally friendly route to produce a wide range of chemicals. Given that the expression of heterologous biosynthetic pathways in plant tissue culture is limited by a lack of detailed protocols, the biosynthesis of high-value metabolites in plant cell culture is constrained compared with that in microbes. However, both Arabidopsis thaliana and Nicotiana benthamiana can be efficiently transformed with multigene constructs to produce high-value natural products in stable plant cell cultures. This chapter provides a detailed protocol as to how to engineer the plant cell culture as bio-factories for metabolite biosynthesis.

C-Terminal Domain Controls Protein Quality and Secretion of Spider Silk in Tobacco Cells

The remarkable mechanical strength and extensibility of spider dragline silk spidroins are attributed to the major ampullate silk proteins (MaSp). Although fragmented MaSp molecules have been extensively produced in various heterologous expression platforms for biotechnological applications, complete MaSp molecules are required to achieve instinctive spinning of spidroin fibers from aqueous solutions. Here, a plant cell-based expression platform for extracellular production of the entire MaSp2 protein is developed, which exhibits remarkable self-assembly properties to form spider silk nanofibrils. The engineered transgenic Bright-yellow 2 (BY-2) cell lines overexpressing recombinant secretory MaSp2 proteins yield 0.6-1.3  µg L-1 at 22 days post-inoculation, which is four times higher than those of cytosolic expressions. However, only 10-15% of these secretory MaSp2 proteins are discharged into the culture media. Surprisingly, expression of functional domain-truncated MaSp2 proteins lacking the C-terminal domain in transgenic BY-2 cells increases recombinant protein secretion incredibly, from 0.9 to 2.8 mg L-1 per day within 7 days. These findings demonstrate significant improvement in the extracellular production of recombinant biopolymers such as spider silk spidroins using plant cells. In addition, the results reveal the regulatory roles of the C-terminal domain of MaSp2 proteins in controlling their protein quality and secretion.

Research Advances in Plant Protein-Based Products: Protein Sources, Processing Technology, and Food Applications

Plant proteins are high-quality dietary components of food products. With the growing interest in sustainable and healthy food alternatives, plant proteins have gained significant attention as viable substitutes for animal-based proteins. Understanding the diversity of protein sources derived from plants, novel processing technology, and multiple applications is crucial for developing nutritious and sustainable plant protein-based products. This Review summarizes the natural sources of traditional and emerging plant proteins. The classifications, processing technologies, and applications of plant protein-based products in the food industry are explicitly elucidated. Moreover, the advantages and disadvantages of plant protein-based food products are revealed. Strategies such as protein fortification and complementation to overcome these shortcomings are critically discussed. We also demonstrate several issues that need to be addressed in future development.

Gibberellic acid 3 enhanced the anticancer activity of Abeliophyllum distichum adventitious roots by activating the diterpenoid biosynthesis pathway

The industrial value of various plants has been improved through the of plant cell culture systems with elicitation. In this study, the adventitious root of Abeliophyllum distichum (AdAR) was treated with gibberellic acid 3 (GA3) to improve its anticancer property. The hexane fraction of the GA3-treated A. distichum adventitious root exhibited a stronger cytotoxic activity against A549 cells than the hexane fraction of AdAR. Through GC/MS and principal component analysis, we identified ferruginol and sugiol as anticancer compounds, which were induced by GA3 treatment in AdAR. Gene expression analysis combined with functional characterisation suggests that the GA3 treatment increased the transcription of geranylgeranyl pyrophosphate synthases and copalyl diphosphate synthase, which led to the accumulation of diterpenoids, including ferruginol and sugiol. Overall, these findings can contribute to the advancement of metabolic engineering for enhancing the biosynthesis of active diterpenoids, and facilitate the large-scale production of bioactive compounds sourced from A. distichum.

Engineering the plant metabolic system by exploiting metabolic regulation

Plants are the most sophisticated biofactories and sources of food and biofuels present in nature. By engineering plant metabolism, the production of desired compounds can be increased and the nutritional or commercial value of the plant species can be improved. However, this can be challenging because of the complexity of the regulation of multiple genes and the involvement of different protein interactions. To improve metabolic engineering (ME) capabilities, different tools and strategies for rerouting the metabolic pathways have been developed, including genome editing and transcriptional regulation approaches. In addition, cutting-edge technologies have provided new methods for understanding uncharacterized biosynthetic pathways, protein degradation mechanisms, protein-protein interactions, or allosteric feedback, enabling the design of novel ME approaches.

Phenolic Compounds from New Natural Sources-Plant Genotype and Ontogenetic Variation

Phenolic compounds (PCs) are widespread secondary metabolites with potent biological activity. Their sources are mainly plants from cultivated and natural states, providing valuable protective and health-promoting extracts. The wide biological activity of PCs (antioxidant, anti-inflammatory, antimicrobial, antiatherosclerotic, antidiabetic, antiallergic, prebiotic, antimutagenic) means that new sources of PCs are constantly being sought, as exemplified by extracting these compounds from tissue culture or agricultural by-products. Plant phenols show marked qualitative and quantitative variation not only at different genetic levels (between and within species and clones) but also between different physiological and developmental stages. Assessing genetic and seasonal variations in phenolic content and activity allows for selecting the best time to harvest the plant. Learning about the causes of PCs' variability and putting this knowledge into practice can significantly increase PCs' yields and extract the most valuable compounds. The health-promoting properties resulting from consuming products rich in plant PCs are undeniable, so it is worth promoting high-phenolic products as a regular diet. This paper presents an overview of different sources of PCs for use as potential therapeutic alternatives. Additionally, factors of variation in the phenolic complex at the genome and ontogeny levels, relevant in practical terms and as a basis for further scientific research, are presented.

Compound-level identification of sasang constitution type-specific personalized herbal medicine using data science approach

Introduction

Sasang Constitutional Medicine (SCM) is a type of traditional Korean medicine where patients are classified as one of four Sasang constitution types (Sasang type) and medications consisting of medicinal herbs are prescribed according to the Sasang type. Despite the importance of personalized medicine, the operation mechanism is largely unknown. To gain a better understanding, we investigated the compound information that composes Sasang type-specific personalized herbal medicines on both multivariate and univariate levels.

Methods

Five machine learning classifiers including extremely randomized trees (ERT) were trained to investigate whether the Sasang type can be explained by compound information at the multivariate level. Hierarchical clustering was conducted to determine whether compounds are processed distributedly or specifically. Taxonomic and biosynthetic analyses were conducted on these compounds. A univariate level statistical test was conducted to provide more robust Sasang type-specific compound information.

Results

Using the trained ERT classifier, sixty important compounds were extracted. The sixty compounds were clustered into three groups, corresponding to each Sasang type-prominent compounds, suggesting that most compounds have specific preference for the Sasang type. Structural and biosynthetic characteristics of these Sasang type-prominent compounds were determined based on taxonomy and pathway analyses. Fourteen compounds showed statistically significant relevance with the Sasang type. Additionally, we predicted the Sasang type of unknown herbs, which were confirmed by their biological effects in functional assays.

Conclusion

This study investigated the personalized herbal medicines of the SCM using compound information. This study provided information on the chemical characteristics of the compounds that are essential for classifying the Sasang type of medicinal herbs, as well as predictions regarding the Sasang type of the commonly used but unidentified medicinal herbs.

Three Parts of the Plant Genome: On the Way to Success in the Production of Recombinant Proteins

Recombinant proteins are the most important product of current industrial biotechnology. They are indispensable in medicine (for diagnostics and treatment), food and chemical industries, and research. Plant cells combine advantages of the eukaryotic protein production system with simplicity and efficacy of the bacterial one. The use of plants for the production of recombinant proteins is an economically important and promising area that has emerged as an alternative to traditional approaches. This review discusses advantages of plant systems for the expression of recombinant proteins using nuclear, plastid, and mitochondrial genomes. Possibilities, problems, and prospects of modifications of the three parts of the genome in light of obtaining producer plants are examined. Examples of successful use of the nuclear expression platform for production of various biopharmaceuticals, veterinary drugs, and technologically important proteins are described, as are examples of a high yield of recombinant proteins upon modification of the chloroplast genome. Potential utility of plant mitochondria as an expression system for the production of recombinant proteins and its advantages over the nucleus and chloroplasts are substantiated. Although these opportunities have not yet been exploited, potential utility of plant mitochondria as an expression system for the production of recombinant proteins and its advantages over the nucleus and chloroplasts are substantiated.

Chemical and Biological Properties of Three Poorly Studied Species of Lycium Genus-Short Review

The genus Lycium belongs to the Solanaceae family and comprises more than 90 species distributed by diverse continents. Lycium barbarum is by far the most studied and has been advertised as a “superfood” with healthy properties. In contrast, there are some Lycium species which have been poorly studied, although used by native populations. L. europaeum, L. intricatum and L. schweinfurthii, found particularly in the Mediterranean region, are examples of scarcely investigated species. The chemical composition and the biological properties of these species were reviewed. The biological properties of L. barbarum fruits are mainly attributed to polysaccharides, particularly complex glycoproteins with different compositions. Studies regarding these metabolites are practically absent in L. europaeum, L. intricatum and L. schweinfurthii. The metabolites isolated and identified belong mainly to polyphenols, fatty acids, polysaccharides, carotenoids, sterols, terpenoids, tocopherols, and alkaloids (L. europaeum); phenolic acids, lignans, flavonoids, polyketides, glycosides, terpenoids, tyramine derivatives among other few compounds (L. schweinfurthii), and esters of phenolic acids, glycosides, fatty acids, terpenoids/phytosterols, among other few compounds (L. intricatum). The biological properties (antioxidant, anti-inflammatory and cytotoxic against some cancer cell lines) found for these species were attributed to some metabolites belonging to those compound groups. Results of the study concluded that investigations concerning L. europaeum, L. intricatum and L. schweinfurthii are scarce, in contrast to L. barbarum.

Chemical profiling of Dizygostemon riparius (Plantaginaceae) plant extracts and its application against larvae of Aedes aegypti L. (Diptera: Culicidae)

Dengue fever is a reemerging disease of global concern among health authorities due to its high rate of proliferation. In 2019, Brazil registered its second-highest dengue mortality rate since 1998, with approximately 754 deaths and 1.5 million probable cases. Brazilian Ministry of Health prevention and control strategies for Aedes include insecticides, eradication of breeding sites, and awareness campaigns. However, as new mosquito variants resistant to conventional insecticides emerge, there is an increasing demand for effective environment-friendly plant extracts and natural substances against adult mosquitos and/or larvae of Aedes aegypti L. with no negative impacts on human health. This study aimed to investigate the larvicidal activity of Dizygostemon riparius extracts and analyze its chemical profile for the first time. Dizygostemon is a Plantaginaceae bytipic genus and D. riparius is an aromatic plant recently identified in Maranhão, Brazil. The essential oil from its lilac morphotype already exhibited larvicidal potential against Aedes albopictus, but the still limited data on this new plant species require further chemical and biological studies on other species, such as Aedes aegypti. Ethyl acetate and methanol crude leaf extracts yielded, respectively, 17.60 and 25.96%. High-performance liquid chromatography (HPLC) with UV detection coupled with electrospray ionization mass spectrometry (HPLC-UV-ESI-IT/MS) analyses confirmed the presence of polymethoxyflavones and coumarins, such as isorhamnetin 3-galactoside-7-rhamnoside, 5,7-dihydroxy-3-(3-hydroxy-4,5-dimethoxyphenyl)-6-methoxy-4-benzopyrone and 3',5-dihydroxy-4',6,7-trimethoxyflavone. Ethyl acetate extract presented the best performance in larvicide bioassays (LC₅₀ = 542.2±11.5 µg.mL^-1). Our results highlight the chemical and biological potential of this new species found in the cerrado of eastern Maranhão and open perspectives for future studies focusing on isolating and identifying other active secondary metabolites of Dizygostemon riparius.

A grobacterium-mediated genetic transformation and cloning of candidate reference genes in suspension cells of Artemisia pallens Wall. ex DC

A reliable and stable Agrobacterium-mediated genetic transformation system for Artemisia pallens has been developed using cell suspension cultures derived from cotyledon explants. Cotyledon, attached cotyledon, and compound leaves were found to be suitable for the induction of callus among five different types of explants tested. The yellow friable callus derived from attached cotyledon was used to initiate suspension cultures in Suspension Culture Medium (SCM) which was supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) at 2.0 mg L-1 and in combination with different concentrations of Zeatin (ZEA) at 0.25 mg L-1. Two different shock treatments, cold shock (at 4 ℃) for 20 min and heat shock (at 45 ℃) treatment for 5 min, heat shock treatment increased the transformation efficiency. The supplementation of Pluronic F-68 (0.05%) significantly enhanced the transformation efficiency of suspension cultures, whereas Silwet L-77 (0.05%) leads to more browning of the cells and reduced the transformation efficiency. The maximum GUS intensity was recorded with an optimal intensity of blue spots in the transformed cells. The highest GUS fluorometric activity measured was 879.4 ± 113.7 nmol 4MU/mg/min in transformed cell suspension cultures. The hygromycin-resistant calli showed intense blue color in GUS histochemical assay. The transgene integration into the plant genome was confirmed by polymerase chain reaction (PCR) using uidA specific primers in six hygromycin-resistant cell lines. The partial coding sequence of three candidate reference genes, i.e., ADP-ribosylation factor (Arf), β-actin (Act), and ubiquitin (Ubi), and carotenoid biosynthesis pathway gene, i.e., Phytoene desaturase (Pds) were cloned, sequenced, and submitted to NCBI for the first time. The quantitative mRNA expression of the transgene (uidA) and internal ApPds gene were evaluated in transgenic callus lines. The present Agrobacterium-mediated genetic transformation protocol could help in better understanding of the metabolic pathways of this medicinally important plant and its genetic improvement.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03251-x.

Linum lewisii Adventitious and Hairy-Roots Cultures as Lignan Plant Factories

Plants synthesize specific secondary metabolites for survival, reproduction, environmental resilience, and defense. Among them, lignans are a class of polyphenols with several bioactive properties: chemopreventive, anti-inflammatory, antiviral, and antioxidant. These compounds are often extracted from field-grown plants with very low yields. To overcome these constraints, in vitro tissue cultures provide a tool to optimize large-scale production. Moreover, the use of elicitation to increase secondary metabolite production is gaining importance. The aim of this work was to develop adventitious (ARL) and hairy roots (HRL) from Linum lewisi, a species able to synthesize arylnaphthalene lignans such as justicidin B. The ARL and HRL were obtained for the first time and characterized for their phenol content, antioxidant activity, and the production of justicidin B after treatments with several elicitors and precursor feeding. Through NMR spectroscopy, other four lignans were highlighted and identified in the roots extracts. A pilot-scale bioreactor was adopted to assess the suitability of the developed root cultures for future large-scale production. The ARL and HRL cultures showed a justicidin B production higher than other Linum species cultures described up to now (75.8 mg/L and 82.2 g/L), and the production more than doubled after elicitation with MeJA.

Antioxidant and Anticancer Potential of Bioactive Compounds from Rhinacanthus nasutus Cell Suspension Culture

The potential benefits of natural plant extracts have received attention in recent years, encouraging the development of natural products that effectively treat various diseases. This is the first report on establishing callus and cell suspension cultures of Rhinacanthus nasutus (L.) Kurz. A yellow friable callus was successfully induced from in vitro leaf explants on Murashige and Skoog medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid and 1 mg/L 1-naphthalene acetic acid. A selected friable callus line was used to establish the cell suspension culture with the same medium. The antioxidant assays showed that the leaf- and ethanolic-suspension-cultured cell (SCC) extracts exhibited high antioxidant potential. In addition, the in vitro cytotoxicity revealed by the MTT assay demonstrated potent antiproliferative effects against the oral cancer cell lines ORL-48 and ORL-136 in a dose-dependent manner. Several groups of compounds, including terpenoids, phenolics, flavonoids, quinones, and stilbenes, were identified by UHPLC–QToF–MS, with the same compounds detected in leaf and SCC extracts, including austroinulin, lucidenic acid, esculetin, embelin, and quercetin 3-(2″-p-hydroxybenzoyl-4″-p-coumarylrhamnoside). The present study suggests the value of further investigations for phytochemical production using R. nasutus cell suspension culture.

Effect of Plant Growth Regulators on Different Explants of Artemisia ludoviciana under Photoperiod and Darkness Conditions and Their Influence on Achillin Production

Species of the genus Artemisia mainly biosynthesize sesquiterpene lactones. Achillin is a guaianolide-type sesquiterpene lactone isolated from Artemisia ludoviciana; it has shown antibacterial and anti-inflammatory activities. In addition, achillin exhibits a significant chemosensitizing effect on hepatocellular carcinoma cells resistant to paclitaxel (PTX). The objective of this study was to establish a callus culture from different explants under conditions of light and total darkness to produce achillin. To obtain in vitro cultures, explants of leaves, nodes, internodes, and roots were used, and they were cultured in MS medium with 0.1 mg/L of kinetin (KIN) or benzyl amino purine (BAP) and/or naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-acetic acid (IAA) and 4-amino-3,5,6-trichloro-2-pyridine carboxylic acid (PIC) at 0.1 and 1.0 mg/L. Of all treatments, internodes with BAP (0.1 mg/L) and PIC (1.0 mg/L) grown under photoperiod showed the best friable callus induction, however, GC-MS analysis showed higher achillin content (1703.05 µg/mL) in leaf calluses with PIC (1.0) and KIN (0.1) under photoperiod, and in node plantlets (1880.01 µg/mL) with PIC (0.1) and BAP (0.1). From 12.34 g of dry leaves of Artemisia ludoviciana, 257 mg of achillin were isolated and purified, which was used as a reference in the quantification of achillin in the in vitro culture.

Overcoming Metabolic Constraints in the MEP-Pathway Enrich Salvia sclarea Hairy Roots in Therapeutic Abietane Diterpenes

Abietane diterpenoids (e.g., carnosic acid, aethiopinone, 1-oxoaethiopinone, salvipisone, and ferruginol) synthesized in the roots of several Salvia species have proved to have promising biological activities, but their use on a large scale is limited by the very low content extracted from in vivo roots. In this review, we summarized our efforts and the achieved results aimed at optimizing the synthesis of these diterpenes in Salvia sclarea hairy roots by either elicitation or by modifying the expression of genes encoding enzymes of the MEP-pathway, the biosynthetic route from which they derive. Stable S. sclarea hairy roots (HRs) were treated with methyl jasmonate or coronatine, or genetically engineered, by tuning the expression of genes controlling enzymatic rate-limiting steps (DXS, DXR, GGPPS, CPPS alone or in combination), by silencing of the Ent-CPPS gene, encoding an enzyme acting at gibberellin lateral competitive route or by coordinate up-regulation of biosynthetic genes mediated by transcription factors (WRKY and MYC2). Altogether, these different approaches successfully increased the amount of abietane diterpenes in S. sclarea HRs from to 2 to 30 times over the content found in the control HR line.

Effect of fruit maturation on N-glycosylation of plant-derived native and recombinant miraculin

Miracle fruit, Synsepalum dulcificum, produces a unique taste-modifying protein, miraculin (MIR), which has an attractive potential for commercial application as a novel low-calorie sweetener. To establish a stable supply system for MIR, a previous study established a platform for recombinant MIR (rMIR) production in tomato plants and demonstrated that native miraculin from miracle fruit (nMIR) and rMIR were almost identical in their protein modifications with N-glycan. However, neither N-glycosylation nor the influence of fruit maturation on the structural changes of N-glycan have been fully characterized in detail. Here, with a focus on N-glycosylation and the contribution of fruit maturation to N-glycan, we reanalyzed the N-glycosylation of the natural maturation stages of nMIR and rMIR, and then compared the N-glycan structures on MIRs prepared from the fruit at two different maturation stages. The detailed peptide mapping and N-glycosylation analysis of MIRs provided evidence that MIRs have variants, which were derived mainly from the differences in the N-glycan structure in nMIR and the N-glycosylation in rMIR and not from the cleavage of the peptide backbone. N-Glycan analysis of MIRs from the maturation stage of fruits demonstrated that N-glycan structures were similar among nMIRs and rMIRs at every maturation stage. These results indicated that the heterogeneously expressed rMIRs had the same characteristics in post-translational modifications, especially N-glycosylation and N-glycan structures, throughout the maturation stages. This study demonstrated the potential of recombinant protein expressed in tomato plants and paves the way for the commercial use of rMIR.

Natural Bioactives: Back to the Future in the Fight against Human Papillomavirus? A Narrative Review

Human papillomavirus (HPV) still represents an important threat to health worldwide. Better therapy in terms of further improvement of outcomes and attenuation of related side-effects is desirable. The pharmaceutical industry has always targeted natural substances-phytochemicals in particular-to identify lead compounds to be clinically validated and industrially produced as antiviral and anticancer drugs. In the field of HPV, numerous naturally occurring bioactives and dietary phytochemicals have been investigated as potentially valuable in vitro and in vivo. Interference with several pathways and improvement of the efficacy of chemotherapeutic agents have been demonstrated. Notably, some clinical trials have been conducted. Despite being endowed with general safety, these natural substances are in urgent need of further assessment to foresee their clinical exploitation. This review summarizes the basic research efforts conducted so far in the study of anti-HPV properties of bio-actives with insights into their mechanisms of action and highlights the variety of their natural origin in order to provide comprehensive mapping throughout the different sources. The clinical studies available are reported, as well, to highlight the need of uniformity and consistency of studies in the future to select those natural compounds that may be suited to clinical application.

Metabolic Perturbation and Synthetic Biology Strategies for Plant Terpenoid Production-An Updated Overview

Terpenoids represent one of the high-value groups of specialized metabolites with vast structural diversity. They exhibit versatile human benefits and have been successfully exploited in several sectors of day-to-day life applications, including cosmetics, foods, and pharmaceuticals. Historically, the potential use of terpenoids is challenging, and highly hampered by their bioavailability in their natural sources. Significant progress has been made in recent years to overcome such challenges by advancing the heterologous production platforms of hosts and metabolic engineering technologies. Herein, we summarize the latest developments associated with analytical platforms, metabolic engineering, and synthetic biology, with a focus on two terpenoid classes: monoterpenoids and sesquiterpenoids. Accumulated data showed that subcellular localization of both the precursor pool and the introduced enzymes were the crucial factors for increasing the production of targeted terpenoids in plants. We believe this timely review provides a glimpse of current state-of-the-art techniques/methodologies related to terpenoid engineering that would facilitate further improvements in terpenoids research.