Protocorm culture of Dendrobium candidum in balloon type bubble bioreactors

Suspension culture of somatic embryos for the production of high-value secondary metabolites

Secondary metabolites from plants are ubiquitous and have applications in medicines, food additives, scents, colorants, and natural pesticides. Biotechnological production of secondary metabolites that have economic benefits is an attractive alternative to conventional methods. Cell, adventitious, and hairy root suspension cultures are typically used to produce secondary metabolites. According to recent studies, somatic embryos in suspension culture are useful tools for the generation of secondary metabolites. Somatic embryogenesis is a mode of regeneration in several plant species. This review provides an update on the use of somatic embryogenesis in the production of valuable secondary metabolites. The factors influencing the generation of secondary metabolites using somatic embryos in suspension cultures, elicitation methods, and prospective applications are also discussed in this review.

Graphical abstract

Production of Secondary Metabolites from Cell Cultures of Sageretia thea (Osbeck) M.C. Johnst. Using Balloon-Type Bubble Bioreactors

Sageretia thea is used in the preparation of herbal medicine in China and Korea; this plant is rich in various bioactive compounds, including phenolics and flavonoids. The objective of the current study was to enhance the production of phenolic compounds in plant cell suspension cultures of Sageretia thea. Optimum callus was induced from cotyledon explants on MS medium containing 2,4-dichlorophenoxyacetic acid (2,4-D; 0.5 mg L^-1), naphthalene acetic acid (NAA, 0.5 mg L^-1), kinetin (KN; 0.1 mg L^-1) and sucrose (30 g L^-1). Browning of callus was successfully avoided by using 200 mg L^-1 ascorbic acid in the callus cultures. The elicitor effect of methyl jasmonate (MeJA), salicylic acid (SA), and sodium nitroprusside (SNP) was studied in cell suspension cultures, and the addition of 200 µM MeJA was found suitable for elicitation of phenolic accumulation in the cultured cells. Phenolic and flavonoid content and antioxidant activity were determined using 2,2 Diphenyl 1 picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethybenzothiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP) assays and results showed that cell cultures possessed highest phenolic and flavonoid content as well as highest DPPH, ABTS, and FRAP activities. Cell suspension cultures were established using 5 L capacity balloon-type bubble bioreactors using 2 L of MS medium 30 g L^-1 sucrose and 0.5 mg L^-1 2,4-D, 0.5 mg L^-1 NAA, and 0.1 mg L^-1 KN. The optimum yield of 230.81 g of fresh biomass and 16.48 g of dry biomass was evident after four weeks of cultures. High-pressure liquid chromatography (HPLC) analysis showed the cell biomass produced in bioreactors possessed higher concentrations of catechin hydrate, chlorogenic acid, naringenin, and other phenolic compounds.

Low Concentration of Anti-Auxin and Anti-Fungal Agent Accelerates the PLB Regeneration of Dendrobium okinawense under Green LED

Dendrobium okinawense is an endangered epiphytic orchid, and there has been no scientific report so far on its propagation. Protocorm is a mass of cells, and protocorm-like bodies (PLBs) are lookalike protocorms produced by vegetative explants in vitro. Regeneration of PLBs is a widely used technique for orchid micropropagation. We used different light-emitting diodes (LEDs) for the PLB regeneration of D. okinawense. The number of PLBs and fresh weight were increased by 81.1% and 80.8%, respectively, under green LED over the white fluorescent (WF) light. We added different concentrations of PCIB (p-Chlorophenoxyisobutyric acid, an anti-auxin) and HMI (3-Hydroxy-5-methyl isoxazole, an anti-fungal agent) in culture media. The number of PLBs was increased in media having 0.01 mg/L of PCIB (35.9%) compared to control (no PCIB), whereas 19.3% increased in media having 0.01 mL/L of HMI compared to control (no HMI). Green LED in combination with 0.01 mg/L of PCIB significantly increased the number of PLBs (69.0%) compared to the WF–without PCIB combination. In LEDs-PCIB and LED-HMI combinations, HMI did not show better PLBs regeneration compared with PCIB. The results suggested that a combination of low concentrations of PCIB and green LED have the potential to accelerate PLB regeneration of D. okinawense.

Shoot Development through Modified Transverse Thin Cell Layer (tTCL) Culture of Phalaenopsis Hybrid Protocorms

This first-attempt study used microtome-based methods to generate a thin cell layer culture for the micropropagation of Phal. Hwafeng Redjewel × Phal. New Cinderella. Protocorms were embedded in various agarose concentrations (8–12%, w/v) and dried from 1 to 8 h before sectioning with a microtome. Optimal conditions for slicing sections of 100 to 300 μm were achieved when the protocorms were embedded at 10% (w/v) agarose and dried for 4 h under laminar flow, and the hardness of the agarose block under these conditions reached 641.8 ± 9.5 g·cm−2. The sectioned protocorms that were cultured on an MS medium supplemented with 1.2 mg·L−1 6-benzylaminopurine and 0.1 mg·L−1 α-naphthaleneacetic acid were capable of growth and differentiated through the neoformation of protocorm-like bodies (PLBs) and/or callus before subsequent regeneration into plantlets and development into healthy plants in a nursery environment. The results of this study demonstrate that microtome-based tTCL is a reliable and promising approach for mass propagation and possible virus-free propagation objectives for Phalaenopsis.

Combined Ultrahigh Pressure Extraction and High-Speed Counter-Current Chromatography for Separation and Purification of Three Glycoside Compounds from Dendrobium officinale Protocorm

As an alternative to Dendrobium candidum, protocorm-like bodies (PLBs) of Dendrobium candidum are of great value due to their high yield and low cost. In this work, three glycoside compounds, β-D-glucopyranose 1-[(E)-3-(4-hydroxyphenyl)-2-propenoat] (I), β-D-glucopyranose 1-[(E)-3-(3, 4-dihydroxyphenyl)-2-propenoat] (II), and 1-O-sinapoyl glucopyranoside (III), were extracted and isolated by ultrahigh pressure extraction (UPE) coupled with high-speed counter-current chromatography (HSCCC) from PLBs of D. officinale. First, the target compounds were optimized and prepared with 50% ethanol solution at a 1:30 (g/mL) solid/liquid ratio in 2 min under 300 MPa by UPE. Then, the crude extract was chromatographed with a silica gel column, and primary separation products were obtained. In addition, the products (150 mg) were separated by HSCCC under the solvent system of MTBE-n-butyl alcohol-acetonitrile-water (5:1:2:6, v/v/v/v), yielding 31.43 mg of compound I, 10.21 mg of compound II, and 24.75 mg of compound III. Their structures were further identified by ESI-MS, ¹H NMR, and ¹³C NMR. The antioxidant results showed that the three compounds expressed moderate effects on the DPPH· scavenging effect. Compound II had the best antioxidant capacity and its IC₅₀ value was 0.0497 mg/mL.

Production of biomass and flavonoid of Gynura procumbens (Lour.) Merr shoots culture in temporary immersion system

Gynura procumbens (Lour.) Merris one of medicinal plant which was carried out used as antioxidant, anticancer, anti-inflammatory, hepatoprotective, and antimicrobial. Many strategies were used to increase the production of biomass and valuable compounds. This study was to investigate the variation effect of growth regulators and immersion frequency on production of biomass and flavonoid contained of G. procumbens shoots culture in temporary immersion bioreactor. Stem nodes were used as an explants and induction of shoots were done in solid MS medium supplemented with many kinds of growth regulator. The best treatments were used to produce biomass and flavonoid compounds in temporary immersion bioreactor; there are combination of IAA 2 mg/L and BA 4, 6, 8 mg/L and immersion frequency (5 min each 3 h; 15 min each 12 h). Results showed that the growths of G. procumbens shoots in solid MS medium were influenced by supplementation of growth regulators. MS medium supplemented with single cytokinine (6 mg/L kinetin) and combination of auxin (IAA) and cytokinine (BA) caused increasing of shoots growth. Production of biomass of G. procumbens in temporary immersion bioreactor was achieved in long immersion interval (12 h) and highest flavonoid production was obtained in combination treatment of immersion frequency 15 min each 12 h and MS medium supplemented with IAA 2 mg/L, BA 8 mg/L.