Bioreactor configurations for adventitious root culture: recent advances toward the commercial production of specialized metabolites

In vitro plant cell and organ cultures are appealing alternatives to traditional methods of producing valuable specialized metabolites for use as: pharmaceuticals, food additives, cosmetics, perfumes, and agricultural chemicals. Cell cultures have been adopted for the production of specialized metabolites in certain plants. However, in certain other systems, adventitious roots are superior to cell suspension cultures as they are organized structures that accumulate high levels of specialized metabolites. The cultivation of adventitious roots has been investigated in various bioreactor systems, including: mechanically agitated, pneumatically agitated, and modified bioreactors. The main relevance and importance of this work are to develop a long-lasting industrial biotechnological technology as well as to improve the synthesis of these metabolites from the plant in vitro systems. These challenges are exacerbated by: the peculiarities of plant cell metabolism, the complexity of specialized metabolite pathways, the proper selection of bioreactor systems, and bioprocess optimization. This review's major objective is to analyze several bioreactor types for the development of adventitious roots, as well as the advantages and disadvantages of each type of bioreactor, and to describe the strategies used to increase the synthesis of specialized metabolites. This review also emphasizes current advancements in the field, and successful instances of scaled-up cultures and the generation of specialized metabolites for commercial purposes are also covered.

3D printing: trends and approaches toward achieving long-term sustainability in the food industry

Global food security has recently been under serious threat from the rapid rise in the world's population, the problems brought on by climate change, and the appearance of new pandemics. As a result, the need for novel and innovative solutions to solve the existing problems and improve food sustainability has become crucial. 3D printing is expected to play a significant role in providing tangible contributions to the food industry in achieving sustainable development goals. The 3D food printing holds the potential to produce highly customized food in terms of shape, texture, flavor, structure and nutritional value and enable us to create new unique formulations and edible alternatives. The problem of whether the cost of the printed meal and 3D printing itself can be sustainably produced is becoming more and more important due to global concerns. This review intends to provide a comprehensive overview of 3D printed foods with an overview of the current printing methodologies, illustrating the technology's influencing factors, and its applications in personalized nutrition, packaging, value addition, and valorization aspects to fully integrate sustainability concerns thus exploring the potential of 3D food printing.

Bioreactor Systems for Plant Cell Cultivation at the Institute of Plant Physiology of the Russian Academy of Sciences: 50 Years of Technology Evolution from Laboratory to Industrial Implications

The cultivation of plant cells in large-scale bioreactor systems has long been considered a promising alternative for the overexploitation of wild plants as a source of bioactive phytochemicals. This idea, however, faced multiple constraints upon realization, resulting in very few examples of technologically feasible and economically effective biotechnological companies. The bioreactor cultivation of plant cells is challenging. Even well-growing and highly biosynthetically potent cell lines require a thorough optimization of cultivation parameters when upscaling the cultivation process from laboratory to industrial volumes. The optimization includes, but is not limited to, the bioreactor's shape and design, cultivation regime (batch, fed-batch, continuous, semi-continuous), aeration, homogenization, anti-foaming measures, etc., while maintaining a high biomass and metabolite production. Based on the literature data and our experience, the cell cultures often demonstrate cell line- or species-specific responses to parameter changes, with the dissolved oxygen concentration (pO2) and shear stress caused by stirring being frequent growth-limiting factors. The mass transfer coefficient also plays a vital role in upscaling the cultivation process from smaller to larger volumes. The Experimental Biotechnological Facility at the K.A. Timiryazev Institute of Plant Physiology has operated since the 1970s and currently hosts a cascade of bioreactors from the laboratory (20 L) to the pilot (75 L) and a semi-industrial volume (630 L) adapted for the cultivation of plant cells. In this review, we discuss the most appealing cases of the cell cultivation process's adaptation to bioreactor conditions featuring the cell cultures of medicinal plants Dioscorea deltoidea Wall. ex Griseb., Taxus wallichiana Zucc., Stephania glabra (Roxb.) Miers, Panax japonicus (T. Nees) C.A.Mey., Polyscias filicifolia (C. Moore ex E. Fourn.) L.H. Bailey, and P. fruticosa L. Harms. The results of cell cultivation in bioreactors of different types and designs using various cultivation regimes are covered and compared with the literature data. We also discuss the role of the critical factors affecting cell behavior in bioreactors with large volumes.

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

Effect of Methyl Jasmonate on the Growth and Biosynthesis of C13- and C14-Hydroxylated Taxoids in the Cell Culture of Yew (Taxus wallichiana Zucc.) of Different Ages

The effects of methyl jasmonate (MeJ) on growth and taxoid formation in the cell culture of Taxus wallichiana were investigated to elucidate the specifics of phytohormone action in dedifferentiated plant cells in vitro. The characteristics of the same suspension cell culture were compared in 2017 (the «young» culture) and in 2022 (the «old» culture)-1.5 or 6 years after culture induction, respectively. MeJ (100 µM) is added to the cell suspension at the end of the exponential growth phase. Cell culture demonstrated good growth (dry weight accumulation 10-18 g/L, specific growth rate µ = 0.15-0.35 day^-1) regardless of its «age», cultivation system, and MeJ addition. UPLC-ESI-MS analysis revealed the presence of C14-hydroxylated taxoids (yunnanxane, taxuyunnanine C, sinenxane C, and sinenxane B) in the cell biomass. The content of C14-OH taxoids increased from 0.2-1.6 mg/gDW in «young» culture to 0.6-10.1 mg/gDW in «old» culture. Yunnanxane was the main compound in «young» culture, while sinenxane C predominated in «old» culture. Without elicitation, small amounts of C13-OH taxoids (<0.05 mg/gDW) were found only in «young» cultures. MeJ addition to «young» culture had no effect on the content of C14-OH taxoids but caused a 10-fold increase in C13-OH taxoid production (up to 0.12-0.19 mg/gDW, comparable to the bark of yew trees). By contrast, MeJ added to «old» culture was not beneficial for the production of C13-OH taxoids but notably increased the content of C14-OH taxoids (1.5-2.0 times in flasks and 5-8 times in bioreactors). These findings suggest that hormonal signaling in dedifferentiated yew cells grown in vitro is different from that in plants and can be affected by the culture's age. This might be a result of the high level of culture heterogeneity and constant auto-selection for intensive proliferation, which leads to the predominant formation of C14-OH taxoids versus C13-OH taxoids and a modified cell response to exogenous MeJ treatment.

Plants, Cells, Algae, and Cyanobacteria In Vitro and Cryobank Collections at the Institute of Plant Physiology, Russian Academy of Sciences-A Platform for Research and Production Center

Ex situ collections of algae, cyanobacteria, and plant materials (cell cultures, hairy and adventitious root cultures, shoots, etc.) maintained in vitro or in liquid nitrogen (-196 °C, LN) are valuable sources of strains with unique ecological and biotechnological traits. Such collections play a vital role in bioresource conservation, science, and industry development but are rarely covered in publications. Here, we provide an overview of five genetic collections maintained at the Institute of Plant Physiology of the Russian Academy of Sciences (IPPRAS) since the 1950-1970s using in vitro and cryopreservation approaches. These collections represent different levels of plant organization, from individual cells (cell culture collection) to organs (hairy and adventitious root cultures, shoot apices) to in vitro plants. The total collection holdings comprise more than 430 strains of algae and cyanobacteria, over 200 potato clones, 117 cell cultures, and 50 strains of hairy and adventitious root cultures of medicinal and model plant species. The IPPRAS plant cryobank preserves in LN over 1000 specimens of in vitro cultures and seeds of wild and cultivated plants belonging to 457 species and 74 families. Several algae and plant cell culture strains have been adapted for cultivation in bioreactors from laboratory (5-20-L) to pilot (75-L) to semi-industrial (150-630-L) scale for the production of biomass with high nutritive or pharmacological value. Some of the strains with proven biological activities are currently used to produce cosmetics and food supplements. Here, we provide an overview of the current collections' composition and major activities, their use in research, biotechnology, and commercial application. We also highlight the most interesting studies performed with collection strains and discuss strategies for the collections' future development and exploitation in view of current trends in biotechnology and genetic resources conservation.

Polyacetylenes from the adventitious roots of Centella asiatica with glucose uptake stimulatory activity

Centella asiatica (L.) Urban is an herbaceous perennial plant of the Apiaceae family that has diverse medicinal uses. Its active components are saponin, phenolics, and polyacetylenes. Plant cell cultures have been exploited for the efficient production of metabolites with pharmacological activity. In this work, we prepared adventitious root cultures of C. asiatica and analyzed their content and biological activity. Adventitious root extracts were found to increase glucose uptake by differentiated L6 skeletal muscle cells and to be more efficient than the extract of whole plants. Chromatographic fractionation of the extracts from adventitious roots of C. asiatica led to the isolation of two known polyacetylenes, araliadiol (1) and 8-acetoxy-1,9-pentadecadiene-4,6-diyn-3-ol (2), in addition to a new polyacetylene, which we have named centellidiol (3). All the three polyacetylenes stimulated glucose uptake in a dose-dependent manner. The methanol extract of adventitious roots contained 0.53% and 0.82% of compounds 1 and 2, respectively, which are values that were 15 and 21 times higher that are found in mother plants. We therefore suggest that the high content of these polyacetylenes contributes to the high efficacy of C. asiatica adventitious root cultures. Overall, adventitious root cultures of C. asiatica can be part of a secure supply of effective ingredients including polyacetylenes.

Sustainable Production of Ajuga Bioactive Metabolites Using Cell Culture Technologies: A Review

The genus Ajuga (Lamiaceae) is rich in medicinally important species with biological activities ranging from anti-inflammatory, antitumor, neuroprotective, and antidiabetic to antibacterial, antiviral, cytotoxic, and insecticidal effects. Every species contains a unique and complex mixture of bioactive metabolites-phytoecdysteroids (PEs), iridoid glycosides, withanolides, neo-clerodane terpenoids, flavonoids, phenolics, and other chemicals with high therapeutic potential. Phytoecdysteroids, the main compounds of interest, are natural anabolic and adaptogenic agents that are widely used as components of dietary supplements. Wild plants remain the main source of Ajuga bioactive metabolites, particularly PEs, which leads to frequent overexploitation of their natural resources. Cell culture biotechnologies offer a sustainable approach to the production of vegetative biomass and individual phytochemicals specific for Ajuga genus. Cell cultures developed from eight Ajuga taxa were capable of producing PEs, a variety of phenolics and flavonoids, anthocyanins, volatile compounds, phenyletanoid glycosides, iridoids, and fatty acids, and demonstrated antioxidant, antimicrobial, and anti-inflammatory activities. The most abundant PEs in the cell cultures was 20-hydroxyecdysone, followed by turkesterone and cyasterone. The PE content in the cell cultures was comparable or higher than in wild or greenhouse plants, in vitro-grown shoots, and root cultures. Elicitation with methyl jasmonate (50-125 µM) or mevalonate and induced mutagenesis were the most effective strategies that stimulated cell culture biosynthetic capacity. This review summarizes the current progress in cell culture application for the production of pharmacologically important Ajuga metabolites, discusses various approaches to improve the compound yield, and highlights the potential directions for future interventions.

The Elicitor Effect of Yeast Extract on the Accumulation of Phenolic Compounds in Linum grandiflorum Cells Cultured In Vitro and Their Antiradical Activity

Abstract

This paper examines the elicitor effect of yeast extract (YE) in various concentrations (200–1000 mg/L) on the accumulation of phenolic compounds (PC) in flowering flax (Linum grandiflorum Desf.) cells cultured in vitro and their antiradical activity. It is established that the total PС content and the content of phenylpropanoids increase in the cell culture, especially at high YE concentrations in the medium (500 and 1000 mg/L). The antiradical activity of flax culture extracts remains in most cases at the control level. Therefore, the elicitation of flowering flax in vitro cultures by YE activates the PC biosynthesis resulting in the accumulation of these secondary metabolites, while the antiradical activity of cell culture extracts does not decrease compared to the control level.

Effect of Phytopreparations Based on Bioreactor-Grown Cell Biomass of Dioscorea deltoidea, Tribulus terrestris and Panax japonicus on Carbohydrate and Lipid Metabolism in Type 2 Diabetes Mellitus

In the present study, we explored the therapeutic potential of bioreactor-grown cell cultures of the medicinal plant species Dioscorea deltoidea, Tribulus terrestris and Panax japonicus to treat carbohydrate metabolism disorders (CMDs) in laboratory rats. In the adrenaline model of hyperglycemia, aqueous suspensions of cell biomass pre-administered at a dose of 100 mg dry biomass/kg significantly reduced glucose level in animal blood 1–2.5 h (D. deltoidea and T. terrestris) or 1 h (P. japonicus) after adrenaline hydrochloride administration. In a streptozotocin-induced model of type 2 diabetes mellitus, the cell biomass of D. deltoidea and T. terrestris acted towards normalization of carbohydrate and lipid metabolism, as evidenced by a significant reduction of daily diuresis (by 39–57%), blood-glucose level (by 46–51%), blood content in urine (by 78–80%) and total cholesterol (25–36%) compared to animals without treatment. Bioactive secondary metabolites identified in the cell cultures and potentially responsible for their actions were deltoside, 25(S)-protodioscin and protodioscin in D. deltoidea; furostanol-type steroidal glycosides and quinic acid derivatives in T. terrestris; and ginsenosides and malonyl-ginsenosides in P. japonicus. These results evidenced for high potential of bioreactor-grown cell suspensions of these species for prevention and treatment of CMD, which requires further investigation.

Curcubinoyl flavonoids from wild ginseng adventitious root cultures

Wild ginseng (Panax ginseng) adventitious root cultures were prepared by elicitation using methyl jasmonate and investigated further to find new secondary metabolites. Chromatographic fractionation of wild ginseng adventitious root cultures led to the isolation of eleven compounds. The chemical structures of isolated compounds were identified as four known flavanone derivatives (1–4), one new curcubinoyl derivative, jasmogin A (5) and six new curcubinoyl-flavanone conjugates, jasmoflagins A-F (6–11) by extensive spectroscopic analysis. Newly isolated curcubinoyl derivatives showed inhibitory activity against lipopolysaccharide-stimulated nitric oxide production in RAW 264.7 macrophages. Therefore, our present study suggested that elicitor stimulated plant cell cultures might contribute to the production of new metabolites.

THE CONTENT OF PHENOLIC COMPOUNDS AND FLAVONOIDS IN Deschampsia antarctica TISSUE CULTURE

Aim. The aim of the study was to determine the quantitative and qualitative content of phenolic compounds and flavonoids in Deschampsia antarctica E. Desv. tissue cultures obtained from plants originating from different islands of the maritime Antarctic. Methods. In vitro tissue culture, Folin-Ciocalteu method, spectrophotometry, HPLC analysis. Results. The quantitative content of phenolic compounds and flavonoids in D. antarctica tissue cultures obtained from plants of six genotypes (DAR12, DAR13, G/D12-2a, Y66, R30 and L57) was determined. The highest content of phenolic compounds (4.46 and 3.75 mg/g) was found in tissue cultures obtained from root and leaf explants of plant genotype L57. The highest amount of flavonoids (7.17 mg/g) was accumulated in G/D12-2a tissue culture of root origin. The content of the studied biologically active compounds (BACs) did not change with increasing number of subculture generations (from passage 10 to 19). HPLC analysis showed that in D. antarctica tissue cultures, a shift in the biosynthesis of BACs occurred towards the synthesis of more polar metabolites compared to explant donor plants. Conclusions. It was found that the transition of cells to undifferentiated growth affected the content of BACs, the amount of which decreased 2–5 times simultaneously with a significant change in their profile. This provided a basis for further biochemical studies, as well as for careful selection of tissue culture of D. antarctica to use it as a potential source of BACs.

Carbon-based nanomaterials as stimulators of production of pharmaceutically active alkaloids in cell culture of Catharanthus roseus

Carbon-based nanomaterials (CBNs) were previously described as regulators of plant cell division. Here, we demonstrated the ability of multi-walled carbon nanotubes (MWCNT) and graphene to enhance biomass production in callus culture of the medicinal plant Catharanthus roseus cultivated in dark conditions. Furthermore, both tested CBNs were able to stimulate biosynthesis of total produced alkaloids in CBN-exposed callus culture of Catharanthus. In one case, total alkaloids in CBN-exposed Catharanthus were double that of unexposed Catharanthus. Analysis of metabolites by HPLC revealed that production of the pharmaceutically active alkaloids vinblastine and vincristine was dramatically enhanced in callus exposed to MWCNT or graphene in both dark and light conditions of callus cultivation. In vitro assays (MTT, flow cytometry) demonstrated that total alkaloid extracts derived from Catharanthus callus treated with CBNs significantly reduced cell proliferation of breast cancer (MCF-7) and lung cancer (A549) cell lines compared to the application of extracts derived from untreated Catharanthus callus.

Plant cell culture technology in the cosmetics and food industries: current state and future trends

The production of drugs, cosmetics, and food which are derived from plant cell and tissue cultures has a long tradition. The emerging trend of manufacturing cosmetics and food products in a natural and sustainable manner has brought a new wave in plant cell culture technology over the past 10 years. More than 50 products based on extracts from plant cell cultures have made their way into the cosmetics industry during this time, whereby the majority is produced with plant cell suspension cultures. In addition, the first plant cell culture-based food supplement ingredients, such as Echigena Plus and Teoside 10, are now produced at production scale. In this mini review, we discuss the reasons for and the characteristics as well as the challenges of plant cell culture-based productions for the cosmetics and food industries. It focuses on the current state of the art in this field. In addition, two examples of the latest developments in plant cell culture-based food production are presented, that is, superfood which boosts health and food that can be produced in the lab or at home.

Colour bio-factories: Towards scale-up production of anthocyanins in plant cell cultures

Anthocyanins are widely distributed, glycosylated, water-soluble plant pigments, which give many fruits and flowers their red, purple or blue colouration. Their beneficial effects in a dietary context have encouraged increasing use of anthocyanins as natural colourants in the food and cosmetic industries. However, the limited availability and diversity of anthocyanins commercially have initiated searches for alternative sources of these natural colourants. In plants, high-level production of secondary metabolites, such as anthocyanins, can be achieved by engineering of regulatory genes as well as genes encoding biosynthetic enzymes. We have used tobacco lines which constitutively produce high levels of cyanidin 3-O-rutinoside, delphinidin 3-O-rutinoside or a novel anthocyanin, acylated cyanidin 3-O-(coumaroyl) rutinoside to generate cell suspension cultures. The cell lines are stable in their production rates and superior to conventional plant cell cultures. Scale-up of anthocyanin production in small scale fermenters has been demonstrated. The cell cultures have also proven to be a suitable system for production of 13C-labelled anthocyanins. Our method for anthocyanin production is transferable to other plant species, such as Arabidopsis thaliana, demonstrating the potential of this approach for making a wide range of highly-decorated anthocyanins. The tobacco cell cultures represent a customisable and sustainable alternative to conventional anthocyanin production platforms and have considerable potential for use in industrial and medical applications of anthocyanins.

Plant cells as food - A concept taking shape

Plant cell cultures from cloudberry, lingonberry and stoneberry were studied in terms of their nutritional properties as food. Carbohydrate, lipid and protein composition, in vitro protein digestibility and sensory properties were investigated. Dietary fibre content varied between 21.2 and 36.7%, starch content between 0.3 and 1.3% and free sugar content between 17.6 and 33.6%. Glucose and fructose were the most abundant sugars. High protein contents between 13.7 and 18.9% were recorded and all samples had a balanced amino acid profile. In vitro protein digestion assay showed hydrolysis by digestive enzymes in fresh cells but only limited hydrolysis in freeze-dried samples. The lipid analysis indicated that the berry cells were rich sources of essential, polyunsaturated fatty acids. In sensory evaluation, all fresh berry cells showed fresh odour and flavour. Fresh cell cultures displayed a rather sandy, coarse mouthfeel, whereas freeze-dried cells melted quickly in the mouth. All in all the potential of plant cells as food was confirmed.

Highlighting mass spectrometric fragmentation differences and similarities between hydroxycinnamoyl-quinic acids and hydroxycinnamoyl-isocitric acids

Background

Plants contain a myriad of metabolites which exhibit diverse biological activities. However, in-depth analyses of these natural products with current analytical platforms remains an undisputed challenge due to the multidimensional chemo-diversity of these molecules, amplified by both isomerization and conjugation. In this study, we looked at molecules such as hydroxyl-cinnamic acids (HCAs), which are known to exist as positional and geometrical isomers conjugated to different organic acids namely quinic- and isocitric acid.

Objective

The study aimed at providing a more defined distinction between HCA conjugates from Amaranthus viridis and Moringa oleifera, using mass spectrometry (MS) approaches.

Methods

Here, we used a UHPLC–MS/MS targeted approach to analyze isobaric HCA conjugates extracted from the aforementioned plants.

Results

Mass spectrometry results showed similar precursor ions and fragmentation pattern; however, distinct differences were seen with ions at m/z 155 and m/z 111 which are associated with isocitric acid conjugates.

Conclusion

Our results highlight subtle differences between these two classes of compounds based on the MS fingerprints, enabling confidence differentiation of the compounds. Thus, these findings provide a template reference for accurate and confident annotation of such compounds in other plants.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-017-0262-8) contains supplementary material, which is available to authorized users.

Plant cell culture strategies for the production of natural products

Plants have evolved a vast chemical cornucopia to support their sessile lifestyles. Man has exploited this natural resource since Neolithic times and currently plant-derived chemicals are exploited for a myriad of applications. However, plant sources of most high-value natural products (NPs) are not domesticated and therefore their production cannot be undertaken on an agricultural scale. Further, these plant species are often slow growing, their populations limiting, the concentration of the target molecule highly variable and routinely present at extremely low concentrations. Plant cell and organ culture constitutes a sustainable, controllable and environmentally friendly tool for the industrial production of plant NPs. Further, advances in cell line selection, biotransformation, product secretion, cell permeabilisation, extraction and scale-up, among others, are driving increases in plant NP yields. However, there remain significant obstacles to the commercial synthesis of high-value chemicals from these sources. The relatively recent isolation, culturing and characterisation of cambial meristematic cells (CMCs), provides an emerging platform to circumvent many of these potential difficulties. [BMB Reports 2016; 49(3): 149-158]

On-line monitoring of the aggregate size distribution of Carthamus tinctorius L. cells with multi-frequency capacitance measurements

This study provided an effective methodology for the aggregate size distribution measurement of Carthamus tinctorius L. cells during suspension culture.

Cambial meristematic cells: a platform for the production of plant natural products

Plant cell culture constitutes a sustainable, controllable and environmentally friendly tool to produce natural products for the pharmaceutical, cosmetic and industrial biotechnology industries. However, there are significant obstacles to the commercial synthesis of high value chemicals from plant culture including low yields, performance instability, slow plant cell growth, industrial scale-up and downstream processing. Cambial meristematic cells constitute a platform to ameliorate many of these potential problems enabling the commercial production of high value chemicals.

Biotechnological approaches to the production of shikonins: a critical review with recent updates

Shikonins are commercially important secondary compounds, known for array of biological activities such as antimicrobial, insecticidal, antitumor, antioxidants, etc. These compounds are usually colored and therefore have application in food, textiles and cosmetics. Shikonin and its derivatives, which are commercially most important of the naphthoquinone pigments, are distributed among members of the family Boraginaceae. These include different species of Lithospermum, Arnebia, Alkanna, Anchusa, Echium and Onosma. The growing demand for plant-based natural products has made this group of compounds one of the enthralling targets for their in vitro production. The aim of this review is to highlight the recent progress in production of shikonins by various biotechnological means. Different methods of increasing the levels of shikonins in plant cells such as selection of cell lines, optimization of culture conditions, elicitation, in situ product removal, genetic transformation and metabolic engineering are discussed. The experience of different researchers working worldwide on this aspect is also considered. Further, to meet market demand, the needs for continuous and reliable production systems, as well as future prospects, are included.

Prospects for the use of plant cell cultures in food biotechnology

Plant cell cultures can offer continuous production systems for high-value food and health ingredients, independent of geographical or environmental variations and constraints. Yet despite many improvements in culture technologies, cell line selection, and bioreactor design, there are few commercial successes. This is principally due to the culture yield and market price of food products not being sufficient to cover the plant cell culture production costs. A better understanding of the underpinning biological mechanisms that control the target metabolite biosynthetic pathways may allow the metabolic engineering of cell lines to provide for economically competitive product yields. However, uncertainty around the regulatory and public acceptance of products derived from engineered cell cultures presents a barrier to the uptake of the technology by food product companies.

Towards a molecular understanding of the biosynthesis of amaryllidaceae alkaloids in support of their expanding medical use

The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor used to treat symptoms of Alzheimer's disease, is produced commercially as a drug from cultivated plants. However, several Amaryllidaceae alkaloids have shown great promise as anti-cancer drugs, but their further clinical development is restricted by their limited commercial availability. Amaryllidaceae species have a long history of cultivation and breeding as ornamental bulbs, and phytochemical research has focussed on the diversity in alkaloid content and composition. In contrast to the available pharmacological and phytochemical data, ecological, physiological and molecular aspects of the Amaryllidaceae and their alkaloids are much less explored and the identity of the alkaloid biosynthetic genes is presently unknown. An improved molecular understanding of Amaryllidaceae alkaloid biosynthesis would greatly benefit the rational design of breeding programs to produce cultivars optimised for the production of pharmaceutical compounds and enable biotechnology based approaches.