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Panax ginseng and Panax quinquefolius of Panax genus are valuable as health foods as well as pharmaceuticals for the treatment of cancer, diabetes and ageing as these plants possess saponins. In the current study, Cell and adventitious root cultures of P. ginseng and P. quinquefolius were investigated for the biomass, cell division, saponin content and ginsenosides profile from four lines namely P. quinquefolius (AM), P. ginseng mountain (Mt.) Baekdu line, P. ginseng Cheong-sol line (CS) and P. ginseng CBN line (CBN) with the objective of comparing cell and adventitious root systems to check their efficacy for the production of ginseng saponins. Additionally, genes related to ginsenoside biosynthesis were also analyzed concerning to cell and adventitious root lines. The results indicated that various cell lines were better in multiplication and growth compared to adventitious root lines. However, adventitious root lines showed higher accumulation of dry biomass (1.5–2 fold) than that of cell lines. CS adventitious root line showed higher saponin content and ginsenoside productivity (10.48 mg·g−1 DW, 12.88 mg·L−1, respectively) than that of CS cell line (9.50 mg·g−1 DW, 2.39 mg·L−1, respectively). Especially, Rd ginsenoside productivity of CS adventitious root line recorded fourfold higher than CS cell line. Genes which are related to ginsenoside biosynthesis such as P. ginseng squalene synthase (PgSS2), P. ginseng squalene epoxidase (PgSE2), P. ginseng protopanaxadial synthase (PgPPDS) and P. ginseng protopanaxatriol synthase (PgPPTS) were analyzed by real time quantitative polymerase chain reaction to support ginsenoside production. The adventitious root culture system described in this study is useful system for biomass and ginsenoside production.

Polygonum multiflorum Thunb. is an important medicinal plant that synthesizes an array of phenolic compounds. Its roots are used in a variety of pharmacological and cosmetic formulations, notably as hair dye. In the present study, the inoculum density (3–15 g/L) and culture period (1–7 weeks) were optimized in a 3 L bioreactor. High root biomass (14.18 g/L dry weight (DW)) was recorded with an inoculum of 7 g/L (p ≤ 0.05), which is consistent with the results for 5 and 10 g/L. However, significantly higher yield of bioactive compounds (53.87 mg/g DW total phenolics and 27.96 mg/g DW total flavonoids) with high free radical scavenging activity was obtained in root samples from 5 g/L inoculum density. A 4 week culture period was sufficient for optimum root growth and metabolite production. The optimized conditions were used for large-scale (5 and 20 L) and pilot-scale (500 L) studies. Considering that the continuous aeration of root cultures may lead to oxidative stress, antioxidant enzyme activity and lipid peroxidation also were studied. The results revealed high catalase (CAT) and guaiacol peroxidase (G-POD) activities, and low malondialdehyde (MDA) production, with increasing culture scale (20 and 500 L), which may indicate low-level oxidative damage to the cultures. An optimal yield of 4.01 kg dry root biomass with 287.12 mg/L of total phenolic productivity was achieved in a 500 L pilot-scale bioreactor. This work can pave the way for commercial production of biomass and secondary metabolites at the industrial level, and meet the rising demand for natural ingredients, especially in the pharmaceutical and cosmetic industries.

A micropropagation system is essential for obtaining elite clones of Phalaenopsis in the floricultural industry; however, somaclonal variation frequently occurs during long-term micropropagation, which reduces the uniformity and quality of clonally propagated plants. To detect the factors influencing this variation and thus obtain high-quality, uniform Phalaenopsis plants, we analyzed somaclonal variants in the Phalaenopsis ‘Spring Dancer’ (SD) variety collected from an orchid farm, which were grouped into three types according to flower morphology (SD-N, SD-V1, SD-V2). Morphological differences were observed between all SD groups; in particular, the diameter of the petal and thickness of each organ were significantly larger in the variants than SD-N (normal) plants. Both SD variant groups showed the same ploidy level as that of SD-N. The degree of endoreduplication of the petals and flower stalks was higher in the variants (4C–16C) than in SD-N (2C–8C). Cell area was increased and the shape of epidermal cells was changed in both variants. Expression levels of MADS box transcription factor (MADS4) of the flowers were higher than those of the leaves in the variants. Among the three flower organs, MADS4 expression was the highest in the petals of SD-V2. These results revealed that MADS4 is involved in the modification of flower morphology in somaclonal SD variants. High ploidy 2 (HPY2) expression was highest in the flowers of SD-V1, whereas its expression in the leaf was similar to that of SD-N. Among the various flower organs, HPY2 expression was highest in the lips of SD-V1.

Shikimate pathway leads to the production of several secondary metabolites including caffeic acid derivatives (CADs), phenols and flavonoids and its regulation is assumed to respond to the requirements for both the synthesis of protein and secondary metabolites. We tested the response of growth, accumulation of phenols, flavonoids, caffeic acid, CADs profiles and activities of shikimate dehydrogenase (SKDH; EC. 1.1.1.25), chorismate mutase (CM; EC. 5.4.99.5), phenylalanine ammonia lyase (PAL; EC. 4.3.1.5) to glyphosate-induced starvation and feeding of aromatic amino acids (l-phenylalanine and l-tryptophan) in adventitious root cultures of Echinacea purpurea. Feeding of l-phenylalanine enhanced the growth but the accumulation of phenols, flavanoids and caffeic acid was lower in comparison to the l-tryptophan fed cultures. The addition of l-tryptophan (0.5, 1 and 5 mM) resulted in an increase up to 56, 61, 84 % in phenol, 24, 12, 3 % in flavonoids and 86, 63, 39 % in total caffeic acid. When glyphosate was added, the growth and accumulation of secondary metabolites were suppressed massively. The addition of l-tryptophan to the media not only countered the deleterious impact of glyphosate but enhanced the growth and accumulation of secondary metabolites in root cultures. The activity of SKDH, CM and PAL induced in presence of l-tryptophan. However, l-phenylalanine addition resulted in increase and decrease of PAL and CM activity, respectively. The presence of glyphosate maximally induced the PAL activity but that could not be translated into higher accumulation of secondary metabolites as it suppresses the accumulation of its substrates i.e. aromatic amino acids. Among CADs, highest cichoric acid and chlorogenic acid was found in l-tryptophan (0.5 mM) which was 2.0 and 1.62 times more than the control treatments. We concluded that addition of l-tryptophan (indolic pathway precursor) and not the l-phenylalanine (phenylpropanoid pathway precursor) stimulate the growth and accumulation of secondary metabolites in adventitious root cultures of E. purpurea (L.) Moench.

To establish an attractive method for the annual production of valuable Eleutherococcus koreanum-based bioactive compounds, the adventitious roots in airlift bioreactors were subjected to methyl jasmonate (MJ) and salicylic acid (SA) treatment for 1 week before harvest as a chemical elicitor to enhance the productivity of bioactive compounds. After 6 weeks of culture, the addition of 50 µmol MJ was found to be the optimal concentration and elicitor type for biomass and bioactive compound production in the roots, as evidenced by the highest biomass and total production of five target bioactive compounds (i.e., eleutherosides B and E, chlorogenic acid, and total phenolics and flavonoids) without causing any physiological disorders. The total production of the target bioactive compounds at 50 µmol MJ (303.93 mg L−1) was 37.77 % higher than that for the control treatment, and the addition of high concentrations of MJ and SA increased 2,2-diphenyl-1-picrylhydrazyl activity and hydrogen peroxide content in the roots. In addition, the adventitious roots subjected to 50 µmol MJ for 1 week had a competitive edge for commercial use, as evidenced by the high total production of the five target bioactive compounds (per 1 L of medium) when compared to the 3-year field-grown plants.

Plant cell and organ cultures have emerged as potential sources of secondary metabolites, which are used as pharmaceuticals, agrochemicals, flavors, fragrances, coloring agents, biopesticides, and food additives. In recent years, various strategies have been developed to assess biomass accumulation and synthesis of secondary compounds in cultures. Biomass accumulation and metabolite biosynthesis are two-stage events, and the parameters that control the growth and multiplication of cultured cells/organs and biomass accumulation are controlled in the first stage. Parameters that assist with the biosynthesis of metabolites are controlled in the second stage. The selection of high-producing cells or organ clones; optimization of medium parameters such as suitable medium, salt, sugar, nitrogen, phosphate, and plant growth regulator levels; and physical factors such as temperature, illumination, light quality, medium pH, agitation, aeration, and environmental gas (e.g., oxygen, carbon dioxide, and ethylene) are controlled in the first stage of the culture process. Elicitation, replenishment of nutrient and precursor feeding, permeabilization, and immobilization strategies assist with the accumulation of metabolites and can be applied in the second stage of the culture process. By following stage-specific strategies, it is possible to produce large amounts of biomass with an increase in the accumulation of secondary compounds.

The Arabidopsis thaliana PRP39, encoding a tetratricopeptide repeat protein, is a novel gene that affects flowering time via an autonomous pathway. In this study, a PRP39 homolog gene was isolated from Doritaenopsis ‘Tinny Tender’ (Doritaenopsis Happy smile × Happy valentine) and designated as DhPRP39. The full-length DhPRP39 cDNA was 2,962 bp long with a 2,472 bp open reading frame and encodes 823 amino acids. The putative DhPRP39-encoded protein contained four conserved, three half-a-tetratricopeptide repeat, and one RNA14 regions. Amino acid sequence alignment showed that DhPRP39 shares a high similarity to PRP39 homologs from other species. Real-time quantitative reverse transcription polymerase chain reaction analysis showed that DhPRP39 is ubiquitously expressed in vegetative and reproductive organs. The transcripts of this gene reached higher levels in the vegetative organs (roots, stems, and leaves) during the transition from vegetative to reproductive growth, in which the stems exhibited the strongest expression. DhPRP39 was overexpressed in Arabidopsis thaliana, and flowering of these transgenic plants were much delayed by 6–7 days compared with wild-type Arabidopsis. DhPRP39 may play an important role in the regulation of plant flowering.

In an attempt to obtain insight into the differential responsiveness of different genotypes of Kalopanax septemlobus regarding their embryogenic capacity, several parameters such as endogenous hormonal levels, DNA content, embryogenic callus proliferation and somatic embryogenesis were studied in several genotypes of this plant. Also, to understand the effect of the age of the explants on their embryogenic capacity, the same parameters were studied in two embryogenic cell lines of different ages in the selected genotype. In the present study, it was observed that the cytokinins/abscisic acid (ABA) ratio plays an important role in embryogenic capacity in the studied genotypes of K. septemlobus species. A decrease in embryogenic capacity of callus was observed with increasing age, along with a marginal decrease in the DNA content of nuclei. Further, it can be suggested from our results that young embryogenic callus is a better choice for somatic embryo formation than the long-term-maintained callus in K. septemlobus.

In this study, we investigated the influence of initial sucrose concentration on the accumulation of biomass, phenols, flavonoids, chlorogenic acid, and hypericin in adventitious root cultures of Hypericum perforatum L. Cultures were initiated in shake flasks by using half-strength Murashige and Skoog (MS) medium, 1.0 mg l−1 indolebutyric acid (IBA), 0.1 m g l−1 kinetin, and different concentrations 0, 1, 3, 5, 7, or 9% in w/v) of sucrose and were maintained in darkness. The medium supplemented with 3% (w/v) sucrose resulted in the optimum biomass accumulation, but higher sucrose concentrations (5, 7, and 9%) inhibited biomass accumulation due to the relatively higher osmotic pressure. However, the amount of total phenols, flavonoids, chlorogenic acid, and total hypericin was increased with the roots grown in the medium supplemented with 5, 7, and 9% (w/v) sucrose. The antioxidant potential of methanolic extract [1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid; ABTS) radical scavenging activities] of H. perforatum adventitious roots was also assessed and correlated with the metabolite accumulation. Cultures maintained with higher initial sucrose concentration (5, 7, and 9% w/v) showed increased accumulation of phenols, flavonoids, chlorogenic acid, and total hypericin, and this might be due to the osmotic stress at elevated sucrose concentrations. To verify the effect of osmotic stress on lipid peroxidation, the levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline were determined in the adventitious roots and the results revealed a marked increase in the concentrations of these compounds. These results suggest that optimal adventitious root biomass could be achieved in the MS medium with 3% (w/v) sucrose and increased sucrose concentration resulted in osmotic stress and, in turn, induces the accumulation of secondary metabolites.

Two-years-old Ginkgo biloba cell culture initiated from cotyledonary explants was cryopreserved by a simple desiccation method. Preliminary incubation of callus clumps on MS preculture medium supplemented with 100 g l−1 sucrose and 2 mg l−1 ABA for 7 and 14 days resulted in accumulation of endogenous soluble sugars and was essential for cell culture post-cryopreservation survival. The optimal time for the preculture on sucrose-and-ABA containing medium was found to be 14 days. The sufficient desiccation duration was determined as 150 min. FCM profiles of calli maintained for 2 years remained stable and were not affected by cryopreservation.

Plantlets of Alocasia amazonica were regenerated on the MS medium supplemented with different concentrations (0–9%) of sucrose. An absence of sucrose in the growth medium induced generation of leaves, however, it decreased multiplication. On contrary, sucrose supply of 6% or 9% enhanced multiplication but hampered photoautotrophic growth (generation of leaves). Increasing sucrose supply also increased sugars and starch content and number of stomata and decreased water potential and size of stomata during in vitro growth period. During ex vitro acclimatization, shoot length, root length, leaf number and root number of Alocasia plantlets grown with 3% sucrose, were found to be better among the other studied sucrose concentrations. Under ex vitro acclimatization, number of stomata, contents of various carbohydrates in the leaves were increased but size of stomata decreased with increasing sucrose supply during in vitro growth period. Moreover, water potential of leaves of plantlets, which have been grown with a sucrose concentration other than 3%, was decreased. During in vitro growth, net CO2 assimilation rate (PN), transpiration (E), stomatal conductance (gs) and variable fluorescence to maximum fluorescence ratio (Fv/Fm) were unaffected, however, during acclimatization these were changed and maximum PN, E, and gs were observed in the plantlets micropropagated with 3% sucrose. Fv/Fm was decreased severely in the plantlets micropropagated with 6% sucrose during acclimatization. Thus a sucrose concentration of 3% in the medium is appeared to be better among studied concentrations for both in vitro growth and ex vitro acclimatization of A. amazonica plantlets.