Potato ( Solanum tuberosum L.) plants were transformed with the desA gene encoding Δ12 acyl-lipid desaturase in the cyanobacterium Synechocystissp. PCC 6803. To evaluate the efficiency of this gene...

The genus Taxus (yew) is a source of a number of high-value medicinal substances, particularly, paclitaxel (taxol)—a complex diterpenoid compound with a powerful antitumor action (trade name of Taxol®). Paclitaxel is one of the most efficient drugs in chemotherapy owing to its specific ability to suppress proliferation of tumor cells via stabilization of their microtubules. The world-wide demand for taxol is 800–1000 kg a year and these figures annually rise by 20%. The growing need for paclitaxel and its derivatives and the shortage of plant resources necessary for their production made compounds of the taxane group one of the most important objects for development of biotechnological methods of their production. Out of all the possible ways of taxol production (isolation from wild or plantation trees, total chemical synthesis or semisynthesis, use of yew cell cultures, techniques of metabolic engineering, and use of yew endophytic fungi), the most promising is industrial cultivation of Taxus spp. cell cultures. This review examines the papers dealing with investigation of secondary metabolism in dedifferentiated cells in vitro of various yew species and feasibility of industrial use of cell cultures for production of taxoids. We revealed a number of specificity of Taxus spp. cell cultures: (1) from a cytophysiological aspect—difficult initiation of cell cultures, their low growth characteristics, specific media and culturing conditions; (2) from a phytochemical aspect—distinction from intact plants in qualitative composition and content of secondary metabolites accounted for by specificity of cell culture as a biological system; predominant formation of С14-hydroxylated rather than of С13-hydroxylated taxoids; an opportunity for elevation of the content of taxoids—including commercially valuable ones (paclitaxel and baccatin III) with the aid of different tools (elicitation, stress exposures, two-phase cultivation and some others); (3) from a biotechnological aspect—possibility of industrial cultivation of yew cell cultures; existence of several successful industries (Germany and the Republic of Korea).

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.

Dioscorea deltoidea is a medicinal plant valued for its high content of steroidal glycosides (SG)—bioactive compounds with cardioprotective and immunomodulation actions, also used to treat reproductive system disorders. To overcome the limitations of natural resources of this species, a suspension cell culture of D. deltoidea was developed as a renewable and ecologically sustainable source of raw biomass and SG. Cell culture demonstrated stable and intensive growth in the laboratory (20 L) and industrial (630 L) bioreactors operated under a semi-continuous regime (specific growth rate 0.11–1.12 day⁻¹, growth index 3.5–3.7). Maximum dry weight accumulation (8.5–8.8 g/L) and SG content (47–57 mg/g DW) were recorded during the stationary phase. Bioreactor-produced cell biomass contained inorganic macro (K, Ca, Mg, Na) and micro (Zn, Mn, Fe, B, Al, Cu, Cr, Se, Co, Ni) elements in concentrations within the safe range of dietary recommendations. Acute toxicity test showed no or insignificant changes in organ weight, hematological panel and blood biochemistry of laboratory animals fed with 2000 and 5000 mg/kg dry biomass. The results suggest that cell culture of D. deltoidea grown in bioreactors has great potential to be used as functional foods and a component of specialized dietary supplements in complex therapy of reproductive system disorders and mineral deficiency.

The embryogenesis capacity of conifer callus is not only highly genotype-dependent, but also gradually lost after long-term proliferation. These problems have seriously limited the commercialization of conifer somatic embryogenesis (SE) technology. In this study, the responsive SE cell line (R-EC), the blocked SE cell line (B-EC), and the loss of SE cell line (L-EC) were studied. The morphological, physiological, transcriptomic, and metabolomic profiles of these three types of cells were analyzed. We found that R-EC had higher water content, total sugar content, and putrescine (Put) content, as well as lower superoxide dismutase (SOD) activity and H₂O₂ content compared to B-EC and L-EC. A total of 2566, 13,768, and 13,900 differentially expressed genes (DEGs) and 219, 253, and 341 differentially expressed metabolites (DEMs) were found in the comparisons of R-EC versus B-EC, R-EC versus B-EC, and B-EC versus L-EC, respectively. These DEGs and DEMs were mainly found to be involved in plant signal transduction, starch and sugar metabolism, phenylpropane metabolism, and flavonoid metabolism. We found that the AUX1 and AUX/IAA families of genes were significantly up-regulated after the long-term proliferation of callus, resulting in higher auxin content. Most phenylpropane and flavonoid metabolites, which act as antioxidants to protect cells from damage, were found to be significantly up-regulated in R-EC.