Optimizing culture conditions for establishment of hairy root culture of Semecarpus anacardium L

Enhanced Production of Nitrogenated Metabolites with Anticancer Potential in Aristolochia manshuriensis Hairy Root Cultures

Aristolochia manshuriensis is a relic liana, which is widely used in traditional Chinese herbal medicine and is endemic to the Manchurian floristic region. Since this plant is rare and slow-growing, alternative sources of its valuable compounds could be explored. Herein, we established hairy root cultures of A. manshuriensis transformed with Agrobacterium rhizogenes root oncogenic loci (rol)B and rolC genes. The accumulation of nitrogenous secondary metabolites significantly improved in transgenic cell cultures. Specifically, the production of magnoflorine reached up to 5.72 mg/g of dry weight, which is 5.8 times higher than the control calli and 1.7 times higher than in wild-growing liana. Simultaneously, the amounts of aristolochic acids I and II, responsible for the toxicity of Aristolochia species, decreased by more than 10 fold. Consequently, the hairy root extracts demonstrated pronounced cytotoxicity against human glioblastoma cells (U-87 MG), cervical cancer cells (HeLa CCL-2), and colon carcinoma (RKO) cells. However, they did not exhibit significant activity against triple-negative breast cancer cells (MDA-MB-231). Our findings suggest that hairy root cultures of A. manshuriensis could be considered for the rational production of valuable A. manshuriensis compounds by the modification of secondary metabolism.

Nicotiana hairy roots for recombinant protein expression, where to start? A systematic review

BACKGROUND

Hairy roots are a plant-tissue culture raised by Rhizobium rhizogenes infection (formerly known as Agrobacterium rhizogenes). Nowadays, these roots have been gaining more space in biotechnology due to their benefits for the recombinant expression of valuables proteins; it includes simplified downstream processing, protein rhizosecretion, and scalability in bioreactors. However, due to methodological inconsistency among reports, the tissue platform is still a promising technology.

METHODS AND RESULTS

In the current paper, we propose the first step to overcome this issue through a systematic review of studies that employ Nicotiana hairy roots for recombinant expression. We conducted a qualitative synthesis of 36 out of 387 publications initially selected. Following the PRISMA procedure, all papers were assessed for exclusion and inclusion criteria. Multiple points of root culture were explored, including transformation methods, root growth curve, external additives, and scale-up with bioreactors to determine which approaches performed best and what is still required to achieve a robust protocol.

CONCLUSION

The information presented here may help researchers who want to work with hairy roots in their laboratories trace a successful path to appraisal the literature status.

Compact shoot architecture of Osteospermum fruticosum transformed with Rhizobium rhizogenes

Improved compact shoot architecture of Osteospermum fruticosum Ri lines obtained through Rhizobium rhizogenes transformation reduces the need for chemical growth retardants. Compactness is for many ornamental crops an important commercial trait that is usually obtained through the application of growth retardants. Here, we have adopted a genetic strategy to introduce compactness in the perennial shrub Cape daisy (Osteospermum fruticosum Norl.). To this end, O. fruticosum was transformed using six different wild type Rhizobium rhizogenes strains. The most effective R. rhizogenes strains Arqua1 and ATCC15834 were used to create hairy root cultures from six Cape daisy genotypes. These root cultures were regenerated to produce transgenic Ri lines, which were analyzed for compactness. Ri lines displayed the characteristic Ri phenotype, i.e., reduced plant height, increased branching, shortened internodes, shortened peduncles, and smaller flowers. Evaluation of the Ri lines under commercial production conditions showed that similar compactness was obtained as the original Cape daisy genotypes treated with growth retardant. The results suggest that the use of chemical growth retardants may be omitted or reduced in commercial production systems of Cape daisy through implementation of Ri lines in future breeding programs.

Genetic transfection, hairy root induction and solasodine accumulation in elicited hairy root clone of Solanum erianthum D. Don

An efficient genetic transfection technique has been established using A4 strain of Agrobacterium rhizogenes for the first time in a medicinally valuable plant Solanum erianthum D. Don. The explants were randomly pricked with sterile needle, inoculated with bacterial suspension. The infected leaves were then washed and transferred to MS basal medium fortified with cefotaxime for hairy root induction. A maximum transformation efficiency of 72 % has been recorded after two days of co-cultivation period. The transfer of rolA and rolB genes from the bacterium to the plant genome has been confirmed in five transformed hairy rootlines by standard Polymerase Chain Reaction technique. On the basis of growth analysis and secondary metabolite study two potential rhizoclones (A4-HR-A and A4-HR-B) were selected. Rhizoclone A4-HR-A can produce highest amount of alkaloid, phenolic and flavonoid, whereas A4-HR-B was observed to be highest tannin producer. Alkaloid like solasodine, commercially important for steroidal drug synthesis, was quantified from leaf and A4-HR-A clone by an improved High Performance Liquid Chromatography method. This showed a sustainable increase (1.33 fold) in production of solasodine in hairy rootline.

Establishment and elicitation of transgenic root culture of Plantago lanceolata and evaluation of its anti-bacterial and cytotoxicity activity

Hairy root induction in Plantago lanceolata was optimized to take advantage of transformed root cultures. The highest frequency of transformation was achieved using leaf explant, A4 strain, pre-cultivation of explant, 150 µM Acetosyringone, 5 min inoculation, half-strength Murashige and Skoog basal medium as co-cultivation, and half-strength Gamborg's basal medium as a selective medium with 3% sucrose. Among the studied compound encompassing gallic acid, catalpol and apigenin, only the production of gallic acid in hairy roots was affected by 20 mg L^-1 AgNO₃ and 100 mg L^-1 chitosan at 24 hr which yielded 7.63, 4.76-fold increase in its content, respectively. The methanolic extracts of hairy roots elicited by 20 mg L^-1 AgNO₃ exhibited anti-bacterial activity (MIC and MBC = 25 mg mL^-1) against Klebsiella pneumoniae, Proteus vulgaris and Salmonella typhi and anti-bacterial potential of non-elicited hairy roots of P. lanceolata (MIC = 25 mg mL^-1 and MBC = 35 mg mL^-1) were more active against Klebsiella pneumoniae and P. vulgaris than other bacteria. The methanolic extracts of the P. lanceolata hairy roots demonstrated significant cytotoxic activity on colorectal carcinoma cell line (SW-480) with IC₅₀ = 250.65 ± 6.8 µg mL^-1 in comparison to human embryonic kidney (HEK-293) with IC₅₀ = 5263.65 ± 4.6 µg mL^-1. Plantago lanceolata hairy roots showed important biological activity explaining its role in traditional medicine.

Production of Flavonoids in Callus Cultures of Sophora flavescens Aiton

Flavonoids, including maackiain (Maac) from Sophora flavescens Aiton roots, have many pharmacological properties, such as antitumor, antimicrobial, and antifungal activities. This research aimed to develop an in vitro plant and callus culture system for S. flavescens for the purpose of generating an alternative production system for enhancing Maac production, as Maac is usually present in very small amounts in S. flavescens' roots. We arranged the optimal conditions of different tissues of S. flavescens and supplemented the medium with various plant growth regulators (PGRs). The highest induction and proliferation rates of callus was shown in combination treatments of all concentrations of thidiazuron (TDZ) and picloram. In addition, calli induced with leaf explants cultured on 2.0 mg/L picloram and 0.5 mg/L 6-benzyladenine (BA) in Murashige and Skoog (MS) medium had the highest accumulation of the active metabolite Maac. In vitro shoots were regenerated on medium containing combinations of TDZ and α-Naphthalene acetic acid (NAA). A reliable protocol for the mass production of secondary metabolites using a callus culture of S. flavescens was successfully established.

Developing a Sufficient Protocol for the Enhancement of α-Glucosidase Inhibitory Activity by Urena lobata L. Aeroponic Hairy Roots Using Exogenous Factors, a Precursor, and an Elicitor

Aeroponics is considered as a potential method for the culture of herbal plants due to the high growth rate, quantity and quality enhancement of secondary metabolites, and substantial environmental progress associated with this method. The aim of this study was to develop a sufficient protocol for successful Urena lobata hairy root induction by Agrobacterium rhizogenes ATCC 15834, using a precursor and elicitor to enhance α-glucosidase inhibitory activity (GIA) of aeroponic hairy roots (AHRs) in greenhouse conditions. In this study, we found that the optimized procedure (10 min, Woody plant medium (WPM), 1/25 salt strength) had an outstanding effect with a reduction in the rooting time (RT), promotion of the rooting rate (RR), and increase in the fresh weight (FW) and dry weight (DW) compared with the original procedure (30 min, Murashige and Skoog (MS) medium, 1/25 salt strength) after 30 days of culture. The highest DW, GIA, flavonoid (FLA) and phenolic (PHEL) contents were observed for individual addition of 10 mM phenylalanine (PA) or 50 mM chitosan (CS) in the late exponential phase (eighth week) with 15 days of elicitation compared to the control AHRs. However, individual treatment was less effective than the combination of the two. Positive correlations among the GIA, FLA and PHEL indicate that AHRs accumulated phenolic compounds, leading to an increase in the GIA by a synergistic effect. In conclusion, the culture of Urena lobata AHRs with PA and CS is an efficient procedure to produce GIA material in greenhouse conditions.

Establishment of in vitro culture system for Codonopsis pilosula transgenic hairy roots

The aim of the study was to establish a reliable system of transgenic hairy roots in Codonopsis pilosula through Agrobacterium-mediated genetic transformation. For this, we optimized several steps in the process of A. rhizogenes strain C58C1 mediated hairy root induction, including the most appropriate medium, explant type, time for infection and co-cultivation. We achieved an induction rate of up to 100% when the roots of C. pilosula seedlings were used as explants, infected with A. rhizogenes C58C1 harboring pCAMBIA1305 for 5 min, followed by induction on 1/2MS supplemented with 0.2 mg/L naphthylacetic acid and 200 mg/L cefotaxime sodium. The co-transformed hairy roots were confirmed by PCR amplification of hygromycin phosphotransferase II gene and histochemical GUS assay, and the efficiency of transformation was 70% and 68.3%, respectively, when no hygromycin selection pressure was exerted. To increase biomass production, we excised and self-propagated the transformed hairy roots, which produce saponins. Our successful establishment of an in vitro culture system of transgenic hairy root for this species lays the foundation not only for assessing gene expression and function but also for obtaining high levels of secondary metabolites through genetic engineering technology.

Hairy root induction and Farnesiferol B production of endemic medicinal plant Ferula pseudalliacea

The effects of medium, gibberellic acid (GA₃) and stratification treatments on the seed germination of Ferula pseudalliacea were evaluated. Filter paper medium, 500 micro molar GA₃ and 8 week chilling treatment were resulted in significantly more seed germination than others. F. pseudalliacea was also transformed by Agrobacterium rhizogenes. Explants from young leaves, stems, cotyledon, and embryo were inoculated with A. rhizogenes strains ATCC 15834, 1724, A4, LB9402 and Ar318. Hairy roots were induced only from 10 to 12-days embryo explants using strains ATCC 15824 and 1724. Although, the transformation efficiency of ATCC 15834 (4%) strain was higher than 1724 (2%). Maximum hairy root transformation frequency (25%) was obtained in infection time of 10 min compared to that of 20 (20%) and 30 (5%) min. In addition, the transformation rate was significantly higher at the inoculation time of 72 h (29%) compared to that of 48 h (22%) and 24 h (6%). Transgenic hairy root lines were confirmed by PCR amplification of rolB gene. Hairy root lines were produced higher biomass in half B5 medium compared to that of half MS medium. Hairy roots lines from the strain ATCC 15834 produced more hairy root numbers and fresh and dried biomass compared to that of the strain 1724. Analyses of transgenic hairy root and natural roots extracts using HPLC showed that all the hairy root lines produced farnesiferol B.

Evaluation of Polyphenolic Compounds and Pharmacological Activities in Hairy Root Cultures of Ligularia fischeri Turcz. f. spiciformis (Nakai)

A considerable amount of bioactive compounds have been used for the biopharmaceutical engineering to help human health and nutrition. Hairy root culture (HRC) or transgenic root is a favourable alternative technique for phytochemical production. Ligularia fischeri is a significant source of pharmaceutically important active compounds with an enormous range of health care applications. HRC of L. fischeri was developed using Agrobacterium rhizogenes for the production of polyphenolic compounds with antioxidant, antimicrobial, antidiabetic, anticancer and anti-inflammatory pharmaceutical activities. Hairy roots (HRs) were selected by morphological assessment, genetic and molecular analyses. The maximum accumulation of fresh mass (94.15 g/L) and dry mass (9.45 g/L) was recorded in MS liquid medium supplemented with 30 g/L sucrose at 28 days. Furthermore, HRs successfully produced numerous polyphenolic compounds, including six hydroxycinnamic acids, seven flavonols, seven hydroxybenzoic acids, vanillin, resveratrol, pyrogallol, homogentisic, and veratric acids, which were identified by UHPLC analysis. HRs produced higher total phenolic (185.65 mg/g), and flavonoid (5.25 mg/g) contents than non-transformed roots (125.55 mg/g and 3.75 mg/g). As a result of these metabolic changes, pharmaceutical activities were found higher in HRs than non-transformed roots (NTRs). The present study indicates that HRC has the potential to increase the content of beneficial polyphenolic compounds with higher potential pharmaceutical activities. To the best of our knowledge, the present study is the first report on enhancing the production of polyphenolic compounds with pharmaceutical activities from the HRCs of L. fischeri.

Specialized Plant Metabolism Characteristics and Impact on Target Molecule Biotechnological Production

Plant secondary metabolism evolved in the context of highly organized and differentiated cells and tissues, featuring massive chemical complexity operating under tight environmental, developmental and genetic control. Biotechnological demand for natural products has been continuously increasing because of their significant value and new applications, mainly as pharmaceuticals. Aseptic production systems of plant secondary metabolites have improved considerably, constituting an attractive tool for increased, stable and large-scale supply of valuable molecules. Surprisingly, to date, only a few examples including taxol, shikonin, berberine and artemisinin have emerged as success cases of commercial production using this strategy. The present review focuses on the main characteristics of plant specialized metabolism and their implications for current strategies used to produce secondary compounds in axenic cultivation systems. The search for consonance between plant secondary metabolism unique features and various in vitro culture systems, including cell, tissue, organ, and engineered cultures, as well as heterologous expression in microbial platforms, is discussed. Data to date strongly suggest that attaining full potential of these biotechnology production strategies requires being able to take advantage of plant specialized metabolism singularities for improved target molecule yields and for bypassing inherent difficulties in its rational manipulation.

Influence of different Agrobacterium rhizogenes strains on hairy root induction and analysis of phenolic and flavonoid compounds in marshmallow (Althaea officinalis L.)

Hairy roots were induced in Althea officinalis using Agrobacterium rhizogenes, strains A4, A13, ATCC15834, and ATCC15834(GUS). The leaf, petiole and shoot explants of marshmallow were used for the hairy roots induction. When hairy roots appeared, cultures were established in MS (Murashige and Skoog) liquid medium without growth regulators. Hairy roots in explants appeared 5-12 days after inoculation. Maximum transformation frequency of 83% was observed on shoot explants with ATCC15834 strain. Among the strains, ATCC15834(GUS) strain showed better potential in the mass production of hairy roots in the hormone-free liquid medium after 50 days of culturing. The highest total phenolic and flavonoids content was found at 1.57 ± 0.1 mg/g dry weight in A13 strain and 3.47 ± 0.3 mg/g in A4 strain, respectively. Secondary metabolite content of hairy roots was found to be strain-specific.

Production of the Anticancer Compound Withaferin A from Genetically Transformed Hairy Root Cultures of Withania Somnifera

Withanolides (WTDs), well-known medicinally important compounds of Withania somnifera, including the anticancer compound withaferin A (WFA), are biosynthesized from their dedicated precursor squalene. Condensation of farnesyl pyrophosphate (FPP) molecules to produce squalene is catalyzed by squalene synthase (SQS). In the present study, the Arabidopsis thaliana squalene synthase gene ( AtSQS1) was transformed in W. somnifera by Agrobacterium tumefaciens C58C1 (pRiA4). The AtSQS1 gene was detected in 87.88 % of induced transformed hairy roots (THRs). The results showed that the growth index (GI) of THRs after five weeks of culture was 2-fold higher than that of adventitious hairy roots (AHRs). The biomass doubling time of THRs and AHRs was 18 and 30 days, respectively. Quantitative evaluation of WFA in the studied roots showed that THRs contain 1.51-fold more WFA (330±0.87μg g−1 dry weight (DW)) than AHRs (218±0.17μg g−1 DW). These findings can be used for the production of WFA as a valuable anticancer compound through controlled and scaled up cultures of W. somnifera THRs.