Instability of anthocyanin accumulation inVitis vinifera L. var. Gamay Fréaux suspension cultures

Influence of the Culture Conditions on Camellia sinensis Cell Cultures

Since the last century, it has been shown that dedifferentiated cells of Camellia sinensis can produce catechins and other secondary metabolites under in vitro conditions, with potential applications in the cosmetic, pharmaceutical and food industries. In this work, cell suspension cultures of a C. sinensis cell line (LSC-5Y) were established in a liquid medium in order to optimize the biomass productivity, catechin monomer (GC, EGC, C, EC, CG, and ECG) and alkaloid (TB and CAF) productivity. The following factors were evaluated: concentration of growth regulators (BA and IBA), inoculum size, age of the cell line, light exposure, and effect of biotic elicitors (MeJA and extracts of Ciborinia camelliae). GC, EGC, and ECG increased approximately 1.80-fold when the auxin IBA concentration was increased from 0.1 to 2.0 mg/L. In addition, better productivity of EGC, C, EC, and CAF was achieved by using inoculum densities between 50 and 100 g/L. Although lower inoculum densities (25 g/L) showed a higher growth rate (0.20 d-1), the use of inoculum densities higher than 25 g/L favors a 2-4-fold increase in total catechin (TC) productivity, with maximum productivity being reached after 21 days of culture. However, the cell line showed instability in TC productivity: in the short term (in three successive subcultures), the coefficient of variation was 32.80%, and catechin production capacity was 2.5 years with maximum productivity at 0.5 years. Finally, it was observed that ethanol, used as an elicitor solvent, has a strong elicitor effect capable of increasing the accumulation of catechins up to 5.24 times compared to the treatment without an elicitor.

Anthocyanin Production from Plant Cell and Organ Cultures In Vitro

Anthocyanins are water-soluble pigments found in plants. They exist in various colors, including red, purple, and blue, and are utilized as natural colorants in the food and cosmetics industries. The pharmaceutical industry uses anthocyanins as therapeutic compounds because they have several medicinal qualities, including anti-obesity, anti-cancer, antidiabetic, neuroprotective, and cardioprotective effects. Anthocyanins are conventionally procured from colored fruits and vegetables and are utilized in the food, pharmaceutical, and cosmetic industries. However, the composition and concentration of anthocyanins from natural sources vary quantitively and qualitatively; therefore, plant cell and organ cultures have been explored for many decades to understand the production of these valuable compounds. A great deal of research has been carried out on plant cell cultures using varied methods, such as the selection of suitable cell lines, medium optimization, optimization culture conditions, precursor feeding, and elicitation for the production of anthocyanin pigments. In addition, metabolic engineering technologies have been applied for the hyperaccumulation of these compounds in varied plants, including tobacco and arabidopsis. In this review, we describe various strategies applied in plant cell and organ cultures for the production of anthocyanins.

In Vitro Cultivation and Ginsenosides Accumulation in Panax ginseng: A Review

The use of in vitro tissue culture for herbal medicines has been recognized as a valuable source of botanical secondary metabolites. The tissue culture of ginseng species is used in the production of bioactive compounds such as phenolics, polysaccharides, and especially ginsenosides, which are utilized in the food, cosmetics, and pharmaceutical industries. This review paper focuses on the in vitro culture of Panax ginseng and accumulation of ginsenosides. In vitro culture has been applied to study organogenesis and biomass culture, and is involved in direct organogenesis for rooting and shooting from explants and in indirect morphogenesis for somatic embryogenesis via the callus, which is a mass of disorganized cells. Biomass production was conducted with different types of tissue cultures, such as adventitious roots, cell suspension, and hairy roots, and subsequently on a large scale in a bioreactor. This review provides the cumulative knowledge of biotechnological methods to increase the ginsenoside resources of P. ginseng. In addition, ginsenosides are summarized at enhanced levels of activity and content with elicitor treatment, together with perspectives of new breeding tools which can be developed in P. ginseng in the future.

Zebularine, a DNA Methylation Inhibitor, Activates Anthocyanin Accumulation in Grapevine Cells

Through its role in the regulation of gene expression, DNA methylation can participate in the control of specialized metabolite production. We have investigated the link between DNA methylation and anthocyanin accumulation in grapevine using the hypomethylating drug, zebularine and Gamay Teinturier cell suspensions. In this model, zebularine increased anthocyanin accumulation in the light, and induced its production in the dark. To unravel the underlying mechanisms, cell transcriptome, metabolic content, and DNA methylation were analyzed. The up-regulation of stress-related genes, as well as a decrease in cell viability, revealed that zebularine affected cell integrity. Concomitantly, the global DNA methylation level was only slightly decreased in the light and not modified in the dark. However, locus-specific analyses demonstrated a decrease in DNA methylation at a few selected loci, including a CACTA DNA transposon and a small region upstream from the UFGT gene, coding for the UDP glucose:flavonoid-3-O-glucosyltransferase, known to be critical for anthocyanin biosynthesis. Moreover, this decrease was correlated with an increase in UFGT expression and in anthocyanin content. In conclusion, our data suggest that UFGT expression could be regulated through DNA methylation in Gamay Teinturier, although the functional link between changes in DNA methylation and UFGT transcription still needs to be demonstrated.

Cellular Agriculture: Opportunities and Challenges

Cellular agriculture is the controlled and sustainable manufacture of agricultural products with cells and tissues without plant or animal involvement. Today, microorganisms cultivated in bioreactors already produce egg and milk proteins, sweeteners, and flavors for human nutrition as well as leather and fibers for shoes, bags, and textiles. Furthermore, plant cell and tissue cultures provide ingredients that stimulate the immune system and improve skin texture, with another precommercial cellular agriculture product, in vitro meat, currently receiving a great deal of attention. All these approaches could assist traditional agriculture in continuing to provide for the dietary requirements of a growing world population while freeing up important resources such as arable land. Despite early successes, challenges remain and are discussed in this review, with a focus on production processes involving plant and animal cell and tissue cultures.

Verbascoside production in long-term Buddleja cordata Kunth cell suspension cultures

Previously, our group reported the establishment of a white callus cell line of Buddleja cordata Kunth that is a high producer of the secondary metabolite, verbascoside (VB, also named acteoside), under suspension culture conditions. Here, we present experimental evidence of the sustained ability of that cellular line to grow and produce high amounts of VB for 5 years of continuous culture. Cellular line profiles were determined at the early (at the beginning) and late stages (at the end of 5 years of continuous subculturing) by analyzing relevant parameters of culture growth, i.e., specific growth rate [µ], doubling time [dt], and growth index [GI], as well as VB production. Late-stage cultures exhibited a 61% faster growth rate than early-stage subcultures, and 25 and 3% lower doubling time and growth index. The extents of growth phases were found to be different. Similar amounts of biomass were found (9.5 g and 9.4 g L-1). Verbascoside production increased parallel to cell growth; maximal yield level occurred in the mid-exponential phase and lasted until the end of the stationary phase (i.e., from the 15th to the 25th day and from the 9th to the 21st day for the early and late stages, correspondingly). The content of VB was higher in the late-stage culture (1.43 ± 0945 g L-1) than in the early-stage culture (1.21 ± 0.0286 g L-1). Productivity values point out the potential use of B. cordata cell line in the biotechnological production of VB and for research focused on the biochemistry of secondary metabolism.

Colchicine Mutagenesis from Long-term Cultured Adventitious Roots Increases Biomass and Ginsenoside Production in Wild Ginseng (Panax ginseng Mayer)

Panax ginseng Mayer is a perennial herb that has been used as a medicinal plant in Eastern Asia for thousands of years. The aim of this study was to enhance root biomass and ginsenoside content in cultured adventitious roots by colchicine mutagenesis. Adventitious P. ginseng roots were treated with colchicine at different concentrations (100, 200, and 300 mg·L−1) and for different durations (1, 2, and 3 days). Genetic variability of mutant lines was assessed using random amplification of polymorphic DNA (RAPD) analysis. Ginsenoside biosynthesis gene expression, ginsenoside content, enzyme activities, and performance in bioreactor culture were assessed in four mutant lines (100–1-2, 100–1-18, 300–1-16, and 300–2-8). The results showed that ginsenoside productivity was enhanced in all mutant lines, with mutant 100–1-18 exhibiting the most pronounced increase (4.8-fold higher than the control). Expression of some ginsenoside biosynthetic enzymes was elevated in mutant lines. Enzyme activities varied among lines, and lipid peroxidation activity correlated with root biomass. All four lines were suitable for bioreactor cultivation, with mutant 100–1-18 exhibiting the highest biomass after culture scale-up. The results indicated that colchicine mutagenesis of P. ginseng roots increased biomass and ginsenosides production. This technique, and the root lines produced in this study, may be used to increase industrial yields of P. ginseng biomass and ginsenosides.

Methyl Jasmonate Induces Enhanced Podophyllotoxin Production in Cell Cultures of Thracian Flax (Linum thracicum ssp. thracicum)

The Linum thracicum ssp. thracicum cell lines developed in this study are a feasible source for the sustainable production of podophyllotoxin, a lignan with an aryltetralin skeleton that is used for the manufacture of the chemotherapeutic drugs etopophos and teniposide. We used mass spectrometry to confirm the presence of the aryltetralin lignan in the thracian flax cell cultures. Next, we explored how changes in the culture medium influenced the podophyllotoxin content. Out of six developed cell lines, four were selected for further experiments and challenged with elicitors. The selected cell lines clustered into two groups: developed in full strength medium (Li) vs developed in half strength medium (HS). While podophyllotoxin production in the Li cell lines was boosted by 80% upon administration of the elicitor methyl jasmonate, the HS lines produced high amounts of the target metabolite triggered by reduced concentration of nutrients and were only slightly influenced by the elicitor.

Cellular aggregation is a key parameter associated with long term variability in paclitaxel accumulation in Taxus suspension cultures

Plant cell cultures provide a renewable source for synthesis and supply of commercially valuable plant-derived products, particularly for secondary metabolites. However, instability in product yields over multiple passages has hampered the efficient and sustainable use of this technology. Paclitaxel accumulation in Taxus cell suspension culture was quantified over multiple passages and correlated to mean aggregate size, extracellular sugar level, ploidy, and cell cycle distribution. Paclitaxel levels varied approximately 6.9-fold over the six-month timeframe investigated. Of all of the parameters examined, only mean aggregate size correlated with paclitaxel accumulation, where a significant negative correlation (r = - 0.75, p < 0.01) was observed. These results demonstrate the relevance of measuring, and potentially controlling, aggregate size during long term culture passages, particularly for plant suspensions where industrially relevant secondary metabolites are not pigmented to enable rapid culture selection.

Monoclonal tobacco cell lines with enhanced recombinant protein yields can be generated from heterogeneous cell suspension cultures by flow sorting

Plant cell suspension cultures can be used for the production of recombinant pharmaceutical proteins, but their potential is limited by modest production levels that may be unstable over long culture periods, reflecting initial culture heterogeneity and subsequent genetic and epigenetic changes. We used flow sorting to generate highly productive monoclonal cell lines from a heterogeneous population of tobacco BY-2 cells expressing the human antibody M12 by selecting the co-expressed fluorescent marker protein DsRed located on the same T-DNA. Separation yielded ∼35% wells containing single protoplasts and ∼15% wells with monoclonal microcolonies that formed within 2 weeks. Thus, enriching the population of fluorescent cells from initially 24% to 90-96% in the six monoclonal lines resulted in an up to 13-fold increase in M12 production that remained stable for 10-12 months. This is the first straightforward procedure allowing the generation of monoclonal plant cell suspension cultures by flow sorting, greatly increasing the potential of plant cells as an economical platform for the manufacture of recombinant pharmaceutical proteins.

Contribution of taxane biosynthetic pathway gene expression to observed variability in paclitaxel accumulation in Taxus suspension cultures

Variability in product accumulation is one of the major obstacles limiting the widespread commercialization of plant cell culture technology to supply natural product pharmaceuticals. Despite extensive process engineering efforts, which have led to increased yields, plant cells exhibit variability in productivity that is poorly understood. Elicitation of Taxus cultures with methyl jasmonate (MeJA) induces paclitaxel accumulation, but to varying extents in different cultures. In the current study, cultures with different aggregation profiles were established to create predictable differences in paclitaxel accumulation upon MeJA elicitation. Expression of known paclitaxel biosynthetic genes in MeJA-elicited cultures exhibiting both substantial (15-fold) and moderate (2-fold) differences in paclitaxel accumulation was analyzed using quantitative reverse transcriptase PCR. Each population exhibited the characteristic large increase in paclitaxel pathway gene expression following MeJA elicitation; however, differences in expression between populations were minor, and only observed for the cultures with the 15-fold variation in paclitaxel content. These data suggest that although upregulation of biosynthetic pathway gene expression contributes to observed increases in paclitaxel synthesis upon elicitation with MeJA, there are additional factors that need to be uncovered before paclitaxel productivity can be fully optimized.