Effect of light wavelength on cell growth, content of phenolic compounds and antioxidant activity in cell suspension cultures of Thevetia peruviana

MsMYB206-MsMYB450-MsHY5 complex regulates alfalfa tolerance to salt stress via regulating flavonoid biosynthesis during the day and night cycles

Flavonoids are the major secondary metabolites participating in many biological processes of plants. Although flavonoid biosynthesis has been extensively studied, its regulatory mechanisms during the day and night cycles remain poorly understood. In this study, three proteins, MsMYB206, MsMYB450, and MsHY5, were found to interact with each other, in which MsMYB206 directly transactivated two flavonoid biosynthetic genes, MsFLS and MsF3'H. The expression patterns of MsMYB206, MsMYB450, MsFLS, and MsF3'H were fully consistent at regular intervals across day/night cycles that were higher at night than in the daytime. On the contrary, both gene expression levels and protein contents of MsHY5 increased in the daytime but decreased at night, and the lower expression of MsHY5 at night led to strengthened interaction between MsMYB206 and MsMYB450. The MsMYB206-overexpression plants were more salt-tolerant and their flavonoid contents were higher than the WT during the day/night cycles. This study revealed one mechanism interpreting the fluctuating flavonoid contents during day/night cycles regulated by the MsMYB206/MsMYB450/MsHY5-MsFLS/MsF3'H module that also contributed to salt tolerance in alfalfa.

Characteristics of Callus and Cell Suspension Cultures of Highbush Blueberry (Vaccinium corymbosum L.) Cultivated in the Presence of Different Concentrations of 2,4-D and BAP in a Nutrient Medium

In this work, cultures of callus and suspension cells originating from leaves of sterile highbush blueberry (Vaccinium corymbosum L.) plants were obtained and characterized. For their active growth and production of phenolic compounds, a combination of 2,4-D at a concentration of 0.34-2.25 µM and BAP at a concentration of 0.45-2.25 µM is effective. An increase in the phytohormone concentration leads to a slowdown in culture formation and reduces their ability to synthesize phenolic compounds. When cultivating V. corymbosum suspension cells over a year (12 passages), they not only retain the ability to synthesize phenolic compounds but also enhance it. By the 12th passage, the content of TSPC in suspension cells reaches 150 mg/g DW, the content of flavonoids reaches 100 mg/g DW, the content of flavans reaches 40 mg/g DW, and the content of proanthocyanidins reaches 30 mg/g DW. The high content of phenolic compounds may be due to the high expression of genes in flavonoid biosynthesis enzymes. V. corymbosum suspension cells accumulate a high level of phenolic compounds during a passage. The ability of V. corymbosum callus and cell suspension cultures in the presence of low concentrations of phytohormones to grow and accumulate biologically active phenolic compounds determines their high economic significance and prospects for organizing a biotechnological method for obtaining phenolic compounds.

Phytochemical characterization of Thevetia peruviana (lucky nut) bark extracts by GC-MS analysis, along with evaluation of its biological activities, and molecular docking study

Thevetia peruviana (T. peruviana; Family: Apocynaceae), commonly known as Lucky Nut, is a traditionally and medicinally important plant, and the barks of the plant are traditionally used as anti-inflammatory, anti-diabetic, and antibacterial remedies. Thus, this study aimed to evaluate bioactive phytochemicals and in-vitro biological activities from the bark of T. peruviana using methanolic (TPM) and dichloromethane (TPD) extracts. The GC-MS analysis showed the presence of 54 and 39 bioactive compounds in TPM and TPD, respectively. The TPM extract has a higher level of total polyphenolic contents (TPC: 70.89 ± 1.08 and 51.07 ± 0.78 mg GAE/g extracts, while TFC: 56.89 ± 1.16 and 44.12 ± 1.76 Qu.E/g extracts for TPM and TPD, respectively). Herein, the results of antioxidant activities were also found in correlation with the total polyphenolic contents i.e., depicting the higher antioxidant potential of TPM compared to TPD. The significant inhibitory activities of extracts were observed against tyrosinase (TPM; 59.43 ± 2.87 %, TPD; 53.43 ± 2.65 %), lipoxygenase (TPM; 77.1 ± 1.2 %, TPD; 59.3 ± 0.1 %), and α-glucosidase (TPM; 71.32 ± 2.44 %, TPD; 67.86 ± 3.011 %). Furthermore, in comparison to co-amoxiclave, the antibacterial property against five bacterial strains was significant assayed. The compounds obtained through GC-MS analysis were subjected to in-silico molecular docking studies, and the phyto-constituents with maximum binding scores were then subjected to ADME analysis. The results of in-silico studies revealed that the binding affinity of several phyto-constituents was even greater than that of the standard inhibitory ligands. ADME analysis showed bioavailability radars of phyto-constituents having maximum docking scores in molecular docking. The results of this study indicated that T. peruviana has bioactive phytochemicals and therapeutic potential and may provide a basis for treating metabolic disorders (inflammatory diseases like rheumatism and diabetes), bacterial infections, and skin-related problems.

Positive Effect of Green Photo-Selective Filter on Graft Union Formation in Tomatoes

This study investigated the effects of green and red photo-selective filters (shade nets) on the process of graft union formation (healing and acclimation) in grafted tomato plants. The research evaluated oxidative stress, physiological characteristics, and anatomical development of graft unions. Plants were subjected to green-netting, red-netting, and no-netting treatments for 28 days, starting 4 days after grafting. Markers of oxidative stress, including reactive oxygen species (ROS), superoxide dismutase (SOD), peroxidase (POD), and malondialdehyde (MDA), as well as protein concentration of SOD/POD enzyme-enriched extracts, were quantified. The anatomical development of the graft unions was examined using microscopy. The results demonstrated that the red and green photo-selective filters increased ROS production by 5% and 4% after 3 days of exposure, by 58% and 14% after 7 days, and by 30% and 13% after 14 days in comparison to the control treatment. The increase in ROS activates the defense mechanism, enhancing the activity of SOD and POD enzymes. In terms of anatomy, the green netting resulted in enhanced cell proliferation and early differentiation of vascular tissue cells. Notably, at the 28-day mark, when the plants were ready for transplanting, the green-net treatment showed a reduction in lipid peroxidation damage and increases of 20% and 54% in dry weight compared with the control and red-net treatments, respectively. Finally, our results suggest that the use of a green photo-selective filter has a positive effect on oxidative stress, anatomical development, and overall growth of grafted tomato plants during the process of graft union formation.

Chemical Characterization of Different Extracts from Artemisia annua and Their Antioxidant, Enzyme Inhibitory and Anti-Inflammatory Properties

Artemisia annua L. (Asteraceae Family) is an important plant in Asia that has been used for treating different diseases, including fever due to malaria, wounds, tubercolisis, scabues, pain, convulsions, diabetes, and inflammation. In this study we aimed to evaluate the effects of different polarity extracts (hexane, dichloromethane, ethyl acetate, ethanol, ethanol/water (70 %) and water) from A. annua against the burden of inflammation and oxidative stress occurring in colon tissue exposed to LPS. In parallel, chemical composition, antiradical, and enzyme inhibition effects against α-amylase, α-glucosidase, tyrosinase, and cholinesterases were evaluated. The water extract contained the highest content of the total phenolic with 34.59 mg gallic acid equivalent (GAE)/g extract, while the hexane had the highest content of the total flavonoid (20.06 mg rutin equivalent (RE)/g extract). In antioxidant assays, the polar extracts (ethanol, ethanol/water and water) exhibited stronger radical scavenging and reducing power abilities when compared to non-polar extracts. The hexane extract showed the best AChE, tyrosinase and glucosidase inhibitory effects. All extracts revealed effective anti-inflammatory agents, as demonstrated by the blunting effects on COX-2 and TNFα gene expression. These effects seemed to be not related to the only phenolic content. However, it is worthy of interest to highlight how the higher potency against LPS-induced gene expression was shown by the water extract ; thus suggesting a potential phytotherapy application in the management of clinical symptoms related to inflammatory colon diseases, although future in vivo studies are needed to confirm such in vitro and ex vivo observations.

Effects of Monochromatic Light on Growth and Quality of Pistacia vera L

Light-emitting diodes (LEDs) are popular as a light source for in vitro plants because they save energy and allow the morphology of the plant to be altered. The purpose of this study was to show that switching from classical fluorescent light (FL) to LED light can have both beneficial and adverse effects. Pistacia vera plantlets were exposed to FL, monochromatic Blue LED light (B), monochromatic Red LED light (R), and a 1:1 mixture of both B and R (BR). R increased the total weight, shoot length, number of shoots ≥ 1 cm, and proliferation. It also reduced hyperhydricity (HH), but also dramatically increased shoot tip necrosis (STN) and leaf necrosis (LN). B cured plants of HH and STN, but hardly enabled proliferation. It did not solve the problem of LN, but the plants were high in total chlorophyll and carotenoids. BR reduced HH but enabled limited proliferation, high STN, and LN. All three LED treatments reduced HH compared to FL. B induced both high total phenolic and flavonoid content and high DPPH-scavenging activity. These results show that switching from FL to LED can have a significant positive or negative effect on proliferation and quality. This suggests that finding an optimal lighting regimen will take a lot of trial and error.

Obtaining 2,3-Dihydrobenzofuran and 3-Epilupeol from Ageratina pichinchensis (Kunth) R.King & Ho.Rob. Cell Cultures Grown in Shake Flasks under Photoperiod and Darkness, and Its Scale-Up to an Airlift Bioreactor for Enhanced Production

Ageratina pichinchensis (Kunth) R.King & Ho.Rob. is a plant used in traditional Mexican medicine, and some biotechnological studies have shown that its calluses and cell suspension cultures can produce important anti-inflammatory compounds. In this study, we established a cell culture of A. pichinchensis in a 2 L airlift bioreactor and evaluated the production of the anti-inflammatory compounds 2,3-dihydrobenzofuran (1) and 3-epilupeol (2). The maximum biomass production (11.90 ± 2.48 g/L) was reached at 11 days of culture and cell viability was between 80% and 90%. Among kinetic parameters, the specific growth rate (µ) was 0.2216 days^-1 and doubling time (td) was 3.13 days. Gas chromatography coupled with mass spectrometry (GC-MS) analysis of extracts showed the maximum production of compound 1 (903.02 ± 41.06 µg/g extract) and compound 2 (561.63 ± 10.63 µg/g extract) at 7 and 14 days, respectively. This study stands out for the significant production of 2,3-dihydrobenzofuran and 3-epilupeol and by the significant reduction in production time compared to callus and cell suspension cultures, previously reported. To date, these compounds have not been found in the wild plant, i.e., its production has only been reported in cell cultures of A. pichinchensis. Therefore, plant cell cultured in an airlift reactor can be an alternative for the improved production of these anti-inflammatory compounds.

Light Quality Modulates Growth, Triggers Differential Accumulation of Phenolic Compounds, and Changes the Total Antioxidant Capacity in the Red Callus of Vitis davidii

Light quality is one of the key elicitors that directly affect plant cell growth and biosynthesis of secondary metabolites. In this study, the red callus of spine grape was cultured under nine light qualities (namely, dark, white, red, yellow, blue, green, purple, warm-yellow, and warm-white light). The effects of different light qualities were studied on callus growth, accumulation of phenolic compounds, and total antioxidant capacity of the red callus of spine grape. The results showed that blue and purple light induced increased red coloration in the callus, whereas yellow light induced the greatest callus proliferation. Among all of the light quality treatments, darkness treatment downregulated the contents of phenolic compounds, whereas blue light was the treatment most conducive to the accumulation of total phenolics. White, blue, and purple light induced increased anthocyanin accumulation. Mixed-wavelength light was beneficial to the accumulation of flavonoids. Blue and purple light were conducive to the accumulation of proanthocyanidins. A further study showed that cyanidin 3-glucoside (Cy3G) and peonidin 3-glucoside (P3G) were the main anthocyanin components in the callus, and blue, purple, and white light treatments promoted their accumulation, whereas flavan-3-ols and flavonols were the main components of non-anthocyanin phenolics, and their accumulation changed in response to not only light quality but also culture duration. The total antioxidant capacity of the callus cultures changed significantly in response to different light qualities. These results will provide evidence for an abiotic elicitor strategy to stimulate callus growth and enhance the accumulation of the main phenolic compounds in the red callus of spine grape.

Gene expression pattern and taxane biosynthesis in a cell suspension culture of Taxus baccata L. subjected to light and a phenylalanine ammonia lyase (PAL) inhibitor

Taxus baccata L. cell culture is a promising commercial method for the production of taxanes with anti-cancer activities. In the present study, a T. baccata cell suspension culture was exposed to white light and 2-aminoindan-2-phosphonic acid (AIP), a phenylalanine ammonia lyase (PAL) inhibitor, and the effects of this treatment on cell growth, PAL activity, total phenol content (TPC), total flavonoid content (TFC), taxane production and the expression of some key taxane biosynthetic genes (DXS, GGPPS, T13OH, BAPT, DBTNBT) as well as the PAL were studied. Light reduced cell growth, whereas AIP slightly improved it. Light increased PAL activity up to 2.7-fold relative to darkness. The highest TPC (24.89 mg GAE/g DW) and TFC (66.94 mg RUE/g DW) were observed in cultures treated with light and AIP. Light treatment also resulted in the maximum content of total taxanes (154.78 μg/g DW), increasing extracellular paclitaxel and cephalomannin (3.3-fold) and intracellular 10-deacetyl paclitaxel (2.5-fold). Light significantly increased the expression level of PAL, DBTNBT, BAPT, and T13αOH genes, whereas it had no effect on the expression of DXS, a gene active at the beginning of the taxane biosynthetic pathway. AIP had no significant effect on the expression of the target genes. In conclusion, the light-induced activation of PAL transcription and altered expression of relevant biosynthetic genes reduced cell growth and increased the content of total phenolic compounds and taxanes. These findings can be applied to improve taxane production in controlled cultures and bioreactors.

Using the Strategy of Inducing and Genetically Transforming Plant Suspension Cells to Produce High Value-Added Bioactive Substances

Plants can produce many functional bioactive substances. The suspension cell system of plants can be constructed based on its characteristics to realize the large-scale production of valuable products. In this review, we mainly talk about the main strategies, elicitation, and genetic transformation to improve the yield of active substances by using this system. Meanwhile, we focus on the challenges hiding in the practical application and the future prospects and provide new ideas and the theoretical basis for obtaining numerous bioactive substances from plants.

LEDitSHAKE: a lighting system to optimize the secondary metabolite content of plant cell suspension cultures

Plant secondary metabolites are widely used in the food, cosmetic and pharmaceutical industries. They can be extracted from sterile grown plant cell suspension cultures, but yields and quality strongly depend on the cultivation environment, including optimal illumination. Current shaking incubators do not allow different light wavelengths, intensities and photoperiods to be tested in parallel. We therefore developed LEDitSHAKE, a system for multiplexed customized illumination within a single shaking incubator. We used 3D printing to integrate light-emitting diode assemblies into flask housings, allowing 12 different lighting conditions (spectrum, intensity and photoperiod) to be tested simultaneously. We did a proof of principle of LEDitSHAKE using the system to optimize anthocyanin production in grapevine cell suspension cultures. The effect of 24 different light compositions on the total anthocyanin content of grapevine cell suspension cultures was determined using a Design of Experiments approach. We predicted the optimal lighting conditions for the upregulation and downregulation of 30 anthocyanins and found that short-wavelength light (blue, UV) maximized the concentration of most anthocyanins, whereas long-wavelength light (red) had the opposite effect. Therefore our results demonstrate proof of principle that the LEDitSHAKE system is suitable for the optimization of processes based on plant cell suspension cultures.

Transcriptomic analyses of cacao flavonoids produced in photobioreactors

BACKGROUND

Theobroma cacao is a major source of flavonoids such as catechins and their monomers proanthocyanidins (PAs), widely studied for their potential benefits in cardiovascular diseases. Light has been shown to promote plant secondary metabolite production in vitro. In this study, cacao cells cultured in 7.5 L stirred tank photobioreactors (STPs) were exposed to a change of white to blue LED lights for 28 days (d).

RESULTS

Transcriptomic analyses were performed in three time points comparing changing expression patterns, after cell exposure to white light (d0-VS-d14), after a shift from white to blue light (d14-VS-d15), and after an extended period of blue light for the following 15 days (d15-VS-d28). Under white light, there was enrichment in metabolic pathways associated with cell growth (carbon, glycolysis, and amino acid biosynthesis) accompanied by a significant increase in the PAs content. In the shift to blue light, further increase in PAs content was observed concomitantly with the significant expression of TWO-COMPONENT RESPONSE REGULATOR genes involved in the early stress responses via circadian clock and hormone pathways. Under blue light exposure, we observed a depletion of PAs content associated with ROS-mediated stress pathways.

CONCLUSIONS

Light effects on large-scale cell cultures in photobioreactors are complex and pleiotropic; however, we have been able to identify key regulatory players upstream cacao flavonoid biosynthesis in STPs, including TWO-COMPONENT SYSTEM and ROS-signaling genes. The crosstalk between flavonoid biosynthesis and regulatory networks led to understand the dynamics of flavonoid production and degradation in response to light-driven ROS signals. This can be used to optimize the time, and the yield of in vitro targeted metabolites in large-scale culture systems.

UV-C mediated accumulation of pharmacologically significant phytochemicals under light regimes in in vitro culture of Fagonia indica (L.)

Fagonia indica (L.) is an important medicinal plant with multitude of therapeutic potentials. Such application has been attributed to the presence of various pharmacological important phytochemicals. However, the inadequate biosynthesis of such metabolites in intact plants has hampered scalable production. Thus, herein, we have established an in vitro based elicitation strategy to enhance such metabolites in callus culture of F. indica. Cultures were exposed to various doses of UV radiation (UV-C) and grown in different photoperiod regimes and their impact was evaluated on biomass accumulation, biosynthesis of phytochemicals along antioxidant expression. Cultures grown under photoperiod (16L/8D h) after exposure to UV-C (5.4 kJ/m²) accumulated optimal biomass (438.3 g/L FW; 16.4 g/L DW), phenolics contents (TPC: 11.8 μgGAE/mg) and flavonoids contents (TFC: 4.05 μgQE/mg). Similarly, HPLC quantification revealed that total production (6.967 μg/mg DW) of phytochemicals wherein kaempferol (1.377 μg/mg DW), apigenin (1.057 μg/mg DW), myricetin (1.022 μg/mg DW) and isorhamnetin (1.022 μg/mg DW) were recorded highly accumulated compounds in cultures at UV-C (5.4 kJ/m²) dose than other UV-C radiations and light regimes.. The antioxidants activities examined as DPPH (92.8%), FRAP (182.3 µM TEAC) and ABTS (489.1 µM TEAC) were also recorded highly expressed by cultures under photoperiod after treatment with UV-C dose 5.4 kJ/m². Moreover, same cultures also expressed maximum % inhibition towards phospholipase A2 (sPLA2: 35.8%), lipoxygenase (15-LOX: 43.3%) and cyclooxygenases (COX-1: 55.3% and COX-2: 39.9%) with 1.0-, 1.3-, 1.3- and 2.8-fold increased levels as compared with control, respectively. Hence, findings suggest that light and UV can synergistically improve the metabolism of F. indica and could be used to produce such valuable metabolites on commercial scale.

Dynamic modelling of growth and flavonoid production from Ocimum tenuiflorum suspension culture

A structured-segregated dynamic model for biomass growth, sucrose utilization and flavonoid production in Ocimum tenuiflorum suspension culture is proposed, considering a dynamic heterogeneous population of viable active, viable nonactive and dead cell. The sucrose hydrolysis (into glucose and fructose), substrate uptake by biomass and intracellular flavonoid production are modelled using Contois kinetics, a competitive double-substrate Monod, and Luedeking-Piret model, respectively. The conversion of active to viable-nonactive biomass has been formulated as a function of the total substrate and biomass concentrations. Parameters for the dynamic model are evaluated while minimizing the sum of square errors between modelled and measured biomass, cell viability, glucose, fructose and intracellular flavonoid contents. Bootstrap confidence intervals and dynamic relative sensitivity analysis of these model parameters are presented. The knowledge gained from the population-based model in plant suspension culture can provide the basic framework for prediction and optimization of the bioprocess system for phytochemical production.

Spectral quality as an elicitor of bioactive compound production in Solanum aculeatissimum JACQ cell suspension

Solanum aculeatissimum Jacq. is a common plant in much of Brazil. Despite containing metabolites with a wide range of pharmacological applications, there are few tissue culture reports for this plant. The possibility of large-scale in vitro production of this material has significant biotechnological potential. Therefore, the objective of this study was to investigate the effect of light conditions on the growth of cells in suspension, observing the production and yield of biomass and bioactive compounds and the enzymatic behavior. Calli obtained from leaf segments were cultured in solid medium supplemented with 1 mg L^-1 of 2,4-D, 2.5 mg L^-1 kinetin, pH 5.7, in the dark. After 110 days of subculture, the calli were transferred to liquid medium. Cells were kept in the dark under agitation at 110 rpm and 25 °C and subcultured every 30 days. After 90 days of culture, 20 mL aliquots of cell suspension were added to flasks containing approximately 20 mL of medium (1:1) and cultured at different wavelengths (white, green, blue, red, and blue/red) under a photoperiod of 16 h with irradiance of 50 μmol m^-2 s^-1) and in the absence of light. The experiment was performed in a 6 × 6 factorial design (light condition × culture time). The cell cultures showed viability throughout the entire cycle, and chlorogenic and ferulic acids, orientin, quercitrin and, in higher amounts, quercetin, were detected in the first 7 days of culture. There was an increase in superoxide dismutase and catalase and a decrease in ascorbate peroxidase after exposure to different light conditions; for phenylalanine ammonia lyase, no differences were observed. The different light conditions were not sufficient to trigger responses in the concentrations of bioactive compounds, despite the detection of increased levels of the enzymes involved in cellular homeostasis.

UPLC-HRMS Analysis Revealed the Differential Accumulation of Antioxidant and Anti-Aging Lignans and Neolignans in In Vitro Cultures of Linum usitatissimum L

Over the last few decades, methods relating to plant tissue culture have become prevalent within the cosmetic industry. Forecasts predict the cosmetic industry to grow to an annual turnover of around a few hundred billion US dollars. Here we focused on Linum usitatissimum L., a plant that is well-known for its potent cosmetic properties. Following the a) establishment of cell cultures from three distinct initial explant origins (root, hypocotyl, and cotyledon) and b) selection of optimal hormonal concentrations, two in vitro systems (callus vs cell suspensions) were subjected to different light conditions. Phytochemical analysis by UPLC-HRMS not only confirmed high (neo)lignan accumulation capacity of this species with high concentrations of seven newly described (neo)lignans. Evaluation over 30 days revealed strong variations between the two different in vitro systems cultivated under light or dark, in terms of their growth kinetics and phytochemical composition. Additionally, antioxidant (i.e. four different in vitro assays based on hydrogen-atom transfer or electron transfer mechanism) and anti-aging (i.e. four in vitro inhibition potential of the skin remodeling enzymes: elastase, hyaluronidase, collagenase and tyrosinase) properties were evaluated for the two different in vitro systems cultivated under light or dark. A prominent hydrogen-atom transfer antioxidant mechanism was illustrated by the DPPH and ABTS assays. Potent tyrosinase and elastase inhibitory activities were also observed, which was strongly influenced by the in vitro system and light conditions. Statistical treatments of the data showed relationship of some (neo)lignans with these biological activities. These results confirmed the accumulation of flax (neo)lignans in different in vitro systems that were subjected to distinct light conditions. Furthermore, we showed the importance of optimizing these parameters for specific applications within the cosmetic industry.

Red light controlled callus morphogenetic patterns and secondary metabolites production in Withania somnifera L

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Combination of thidiazuron and naphthalene acetic acid induced callus growth in Withania somnifera.

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Red light improved callus growth with lower antioxidant enzymes activities.

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Violet light enhanced the total phenolic and flavonoid content in callus culture of W. somnifera.

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Withaferin A and chlorogenic acid were detected in callus cultures.

Withania somnifera L. is an endangered medicinal plant of higher market value. The in vitro callus cultures were established on Murashige and Skoog (MS) media augmented with different plant growth regulators. The MS medium containing 0.5 mg∙L⁻¹ of each TDZ and NAA was found to be optimal for callus formation and growth. Further, callus cultures were raised in different light wavelengths to find the right wavelength carrying the photons for the ideal cell growth of W. somnifera. Among the different wavelengths, red light was best for maximum biomass accumulation in callus culture. However, violet light condition was proven to be favouring the phenols and flavonoids synthesis in the callus cultures. Compared to other wavelengths, red light grown callus extract showed significantly higher content of chlorogenic acid, and withaferin A. This study concludes that red light treatment was optimum for maximum biomass accumulation and anti-oxidant activity in calli of W. somnifera.

The effect of light, phenylalanine and methyl jasmonate, alone or in combination, on growth and secondary metabolism in cell suspension cultures of Vitis vinifera

The cultivated grapevine V. vinifera is a rich source of stilbene compounds such as resveratrol, which are widely believed to provide dietary protection against the development of cardiovascular disease and some forms of cancer. Elicitation is a well-known strategy to increase commercial production of natural products in plant cell suspension culture systems. Callus tissues obtained from berry slices of V. vinifera cv. Shahani grown on an optimized medium were used to develop cell suspension cultures used to study the effects of elicitation on stilbene synthesis. The effect of two light regimes (135.1 μmol. s^-1 m^-2 radiation, and dark), the concentration of phenylalanine (Phe; 0, 0.1, 0.5 and 1 mM) and of methyl jasmonate elicitor (MeJA; 0 and 25 μM), alone or in combination, were tested. The results showed that cultures grown in darkness resulted in significantly higher levels of the accumulation of total stilbenes (resveratrol + piceid) compared with the high light condition. The combined treatments of dark +1 mM Phe and dark +25 μM MeJA induced the synthesis of high levels of total phenolics, total flavonoids and total stilbenes. Finally, the combined elicitation of dark +1 mM Phe + 25 μM MeJA gave the highest synergistic coefficient (1.24) and proved to be the most effective treatment for the production of total phenolics, total flavonoids, and total stilbenes with mean contents of 384.80 mg GA/g DW, 527.62 mg catechin/g DW and 188.34 μg/g DW, respectively. The results of our study suggest that the combinations of dark together with MeJA and/or Phe can be used as an efficient method for the future scale-up of V. vinifera cell cultures for the production of high value stilbene compounds in a bioreactor system.

Cell Suspension Culture of Plumbago europaea L. Towards Production of Plumbagin

BACKGROUND

Plumbagin is as an important bioactive secondary metabolite found in the roots of Plumbago spp. The only one species, Plumbago europaea L., grows wild in Iran. The therapeutic use of plumbagin is limited due to its insufficient supply from the natural sources as the plants grow slowly and take several years to produce quality roots.

OBJECTIVES

To develop an efficient protocol for the establishment of callus and cell suspension cultures of P. europaea and to evaluate production of plumbagin in callus and cell suspension cultures of P. europaea for the first time.

MATERIAL AND METHODS

Stems and leaves explants were cultured on agar solidified (7% w/v) MS media, supplemented with different combination of 2, 4-D and Kin or 6-Benzylaminopurin (BA) for callus induction. The rapid growing calli were cultured in liquid Murashige and Skoog (MS) media in agitated condition for establishing cell suspension cultures of P. europaea. Moreover, the effects of light and dark conditions on the cell growth, cell viability and plumbagin production in cell suspension cultures of P. europaea were assessed.

RESULTS

Friable calli were successfully induced using stem segments of P. europaea in semisolid MS medium supplemented with 1 mg.L-1 2, 4-Dichlorophenoxy acetic acid (2, 4-D) and 0.5 mg.L-1of kinetin (Kin). Optimal cell growth was obtained when the cells were grown in MS liquid media supplemented with 1 mg.L-1 2, 4-D and 0.5 mg.L-1 kinetin with an initial cell density of ~3×105 cells per ml incubated in the dark at 25 ± 1 °C. Growth curve revealed that the maximum cell growth rate (14.83×105 cells per ml) achieved on the day 18 and the highest plumbagin content (0.9 mg.g-1 Dry Cell Weight (DCW)) in the cells was obtained at the late exponential phase under dark condition which determined by High Performance Liquid Chromatography (HPLC) technique. Based on the obtained results, cell viability remained around 82.73% during the 18 days of cell culture in darkness. These suspension cultures showed continuous and stable production of plumbagin.

CONCLUSIONS

Our study suggests that cell suspension cultures of P. europaea represent an effective system for biosynthesis and production of plumbagin as a valuable bioactive compound.

Transcriptomic analyses of cacao cell suspensions in light and dark provide target genes for controlled flavonoid production

Catechins, including catechin (C) and epicatechin (E), are the main type of flavonoids in cacao seeds. They play important roles in plant defense and have been associated with human health benefits. Although flavonoid biosynthesis has been extensively studied using in vitro and in vivo models, the regulatory mechanisms controlling their accumulation under light/dark conditions remain poorly understood. To identify differences in flavonoid biosynthesis (particularly catechins) under different light treatments, we used cacao cell suspensions exposed to white-blue light and darkness during 14 days. RNA-Seq was applied to evaluate differential gene expression. Our results indicate that light can effectively regulate flavonoid profiles, inducing a faster accumulation of phenolic compounds and shifting E/C ratios, in particular as a response to switching from white to blue light. The results demonstrated that HY5, MYB12, ANR and LAR were differentially regulated under light/dark conditions and could be targeted by overexpression aiming to improve catechin synthesis in cell cultures. In conclusion, our RNA-Seq analysis of cacao cells cultured under different light conditions provides a platform to dissect key aspects into the genetic regulatory network of flavonoids. These light-responsive candidate genes can be used further to modulate the flavonoid production in in vitro systems with value-added characteristics.

Effect of salicylic acid and methyl jasmonate in the production of phenolic compounds in plant cell suspension cultures of Thevetia peruviana

The objective was to enhance the production of the phenolic compounds in plant cell suspension cultures of T. peruviana at shake flask scale. The effects of salicylic acid (SA), methyl-jasmonate (MeJA) and the combination of both (SA/MeJA) were studied. Elicitor concentration, elicitation time and harvest time of cells were optimized. Phenolic compound content (PCC), flavonoid content (FC) and antioxidant activity (AA) were determined by the folin-ciocalteu method, flavonoid-aluminum complexation method and the ABTS assay, respectively. Differences between intracellular metabolite profiles due to the mentioned treatments were analyzed by Thin-layer chromatography and High-performance liquid chromatography. Highest PCC, FC and AA were obtained under the following treatments: 3 μM MeJA > 3 μM MeJA/300 μM SA > 300 μM SA > control, when elicited on the 4^th day and harvested 96-h post-elicitation. It was demonstrated that exposure to 3 μM MeJA increase 1.49-fold of PCC, 1.66-fold of AA and 2.55-fold of FC compared to the control culture.

Single Laboratory Validation of a Quantitative Core Shell-Based LC Separation for the Evaluation of Silymarin Variability and Associated Antioxidant Activity of Pakistani Ecotypes of Milk Thistle (Silybum Marianum L.)

Fruits of Silybum marianum (L.) Gaernt are the main source of taxifolin derived flavonolignans. Together, these molecules constitute a mixture called silymarin with many useful applications for cosmetic and pharmaceutic industries. Here, a validated method for the separation of the silymarin constituents has been developed to ensure precision and accuracy in their quantification. Each compound was separated with a high reproducibility. Precision and repeatability of the quantification method were validated according to the AOAC recommendations. The method was then applied to study the natural variability of wild accessions of S. marianum. Analysis of the variation in the fruits composition of these 12 accessions from Pakistan evidenced a huge natural diversity. Correlation analysis suggested a synergistic action of the different flavonolignans to reach the maximal antioxidant activity, as determined by cupric ion reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) assays. Principal component analysis (PCA) separated the 12 accessions into three distinct groups that were differing from their silymarin contents, whereas hierarchical clustering analysis (HCA) evidenced strong variations in their silymarin composition, leading to the identification of new silybin-rich chemotypes. These results proved that the present method allows for an efficient separation and quantification of the main flavonolignans with potent antioxidant activities.

Ethnopharmacology, phytochemistry, and biotechnological advances of family Apocynaceae: A review

The family Apocynaceae is one of the largest and important families in angiosperm. Several members of this family have medicinal properties and have been in the treatment of various ailments. Most of them are consumed as food by tribal people whereas a few plants are used as source of poison. Members of family Apocynaceae are rich in alkaloids, terpenoids, steroids, flavonoids, glycosides, simple phenols, lactones, and hydrocarbons. Other compounds such as sterols, lignans, sugars, lignans, and lactones have been isolated and systematically studied. Few studies have reported antioxidant, anti-inflammatory, antimicrobial, and cytotoxic activities of crude extracts as well as single compound(s) isolated from various members of the family Apocynaceae. Holarrhena antidysenterica, Rauvolfia serpentina, Carissa carandas, and Tabernaemontana divaricata are the extensively studied plants in this family. The present review provides a detailed outlook on ethnopharmacology, phytochemistry, and biological activities of selected members of this family. Moreover, it also covers the biotechnological advances used for large-scale production of bioactive compounds of therapeutic interest along with plant tissue culture-based approaches for conservation of this medicinally valuable family.

Effects of photoperiod regimes and ultraviolet-C radiations on biosynthesis of industrially important lignans and neolignans in cell cultures of Linum usitatissimum L. (Flax)

Lignans and neolignans are principal bioactive components of Linum usitatissimum L. (Flax), having multiple pharmacological activities. In present study, we are reporting an authoritative abiotic elicitation strategy of photoperiod regimes along with UV-C radiations. Cell cultures were grown in different photoperiod regimes (24h-dark, 24h-light and 16L/8D h photoperiod) either alone or in combination with various doses (1.8-10.8kJ/m²) of ultraviolet-C (UV-C) radiations. Secoisolariciresinol diglucoside (SDG), lariciresinol diglucoside (LDG), dehydrodiconiferyl alcohol glucoside (DCG), and guaiacylglycerol-β-coniferyl alcohol ether glucoside (GGCG) were quantified by using reverse phase-high performance liquid chromatography (RP-HPLC). Results showed that the cultures exposed to UV-C radiations, accumulated higher levels of lignans, neolignans and other biochemical markers than cultures grown under different photoperiod regimes. 3.6kJ/m² dose of UV-C radiations resulted in 1.86-fold (7.1mg/g DW) increase in accumulation of SDG, 2.25-fold (21.6mg/g DW) in LDG, and 1.33-fold (9.2mg/g DW) in GGCG in cell cultures grown under UV+photoperiod than their respective controls. Furthermore, cell cultures grown under UV+dark showed 1.36-fold (60.0mg/g DW) increase in accumulation of DCG in response to 1.8kJ/m² dose of UV-C radiations. Smilar trends were observed in productivity of SDG, LDG and GGCG. Additionally, 3.6kJ/m² dose of UV-C radiations also resulted in 2.82-fold (195.65mg/l) increase in total phenolic production, 2.94-fold (98.9mg/l) in total flavonoid production and 1.04-fold (95%) in antioxidant activity of cell cultures grown under UV+photoperiod. These findings open new dimensions for feasible production of biologically active lignans and neolignans by Flax cell cultures.