Hairy Roots

Agrobacterium rhizogenes induces hairy root disease in plants. The neoplastic (cancerous) roots produced by A. rhizogenes infection, when cultured in hormone free medium, show high growth rate and genetic stability. These genetically transformed root cultures can produce levels of secondary metabolites comparable to that of intact plants. Several elicitation methods can be used to further enhance the production and accumulation of secondary metabolites. Thus, hairy root culture offer promise for high production and productivity of valuable secondary metabolites in many plants. Hairy roots can also produce recombinant proteins from transgenic roots, and thereby hold immense potential for pharmaceutical industry. Hairy root cultures can be used to elucidate the intermediates and key enzymes involved in the biosynthesis of secondary metabolites, and for phytoremediation due to their abundant neoplastic root proliferation property. Various applications of hairy root cultures and potential problems associated with them are discussed in this chapter.

A Simple and Efficient Protocol for Hairy Root Culture of Arabidopsis Thaliana

Hairy root culture (HRC) is a valuable biotechnological tool for the production of plant secondary metabolites. Secondary metabolome study of Arabidopsis thaliana can be helpful in understanding the biological roles of various secondary metabolites present in it and HRC constructs the base of such study. The present work deals with the establishment of Agrobacterium rhizogenes strains transformed HRC of A. thaliana with very high transformation frequency resulting in long term hairy root cultures grown in hormone free media. Optimization of culture medium and standardisation of co-cultivation period are the key role players in obtaining high frequency of hairy roots. Four days of preculture in CIM medium and five min of co-cultivation in the bacterial suspension were found to be optimal conditions for root induction. This protocol could become a powerful tool for transcriptomics and proteomics-based studies for different transgenic root lines of A. thaliana.

A Comparative Study of Apigenin Content and Antioxidant Potential of CosmosBipinnatus Transgenic Root Culture

Background: Flavonoid-derived components have been studied for their therapeutic properties. Objectives: Apigenin has shown remarkable antioxidant and anti-inflammatory features, so we should have a reliable source of apigenin. Methods: In this study, we used high-performance liquid chromatography method to compare the amount of apigenin in flower, root, leaf, and stem of three varieties of osmos bipinnatus, i.e., ‘Dazzler,’ ‘Xanthos,’ ‘Sensation Pinkie’, and in transgenic root culture of C. bipinnatus ‘Dazzler’. Besides, the antioxidant activity of C. bipinnatus ‘Dazzler’ transgenic root culture was evaluated using Ferric Reducing Antioxidant Power (FRAP) assay. Results: Dazzler variety flowers showed the highest recovery of apigenin with 0.799 mg/100 mg Dry Weight (DW). However, the Sensation pinkie variety leafs had the lowest recovery with 0.089 mg/100mg. Apigenin content in transformed roots (0.797 mg/100 mg DW) of C. bipinnatus ‘Dazzler’ was significantly higher than non-transformed roots (0.42 mg/100 mg DW). The ethanolic extract of hairy root showed the FRAP value of 668.1 µM Fe2+/mg that was comparatively more than the wild root FRAP value (426.2 µM Fe2+/mg). Conclusion: In conclusion, the presence of apigenin in high amounts in hairy root cultures of C. bipinnatus ‘Dazzler’ indicates its great potential for the future pharmaceutical industry.

The combination of R2R3-MYB gene AmRosea1 and hairy root culture is a useful tool for rapidly induction and production of anthocyanins in Antirrhinum majus L

Anthocyanins are the largest group of water-soluble pigments and beneficial for human health. Although most plants roots have the potential to express natural biosynthesis pathways required to produce specialized metabolites such as anthocyanins, the anthocyanin synthesis is specifically silenced in roots. To explore the molecular mechanism of absence and production ability of anthocyanin in the roots, investigated the effect of a bHLH gene AmDelila, and an R2R3-MYB gene AmRosea1, which are the master regulators of anthocyanin biosynthesis in Antirrhinum majus flowers, by expressing these genes in transformed hairy roots of A. majus. Co-ectopic expression of both AmDelila and AmRosea1 significantly upregulated the expression of the key target structural genes in the anthocyanin biosynthesis pathway. Furthermore, this resulted in strongly enhanced anthocyanin accumulation in transformed hairy roots. Ectopic expression of AmDelila alone did not gives rise to any significant anthocyanin accumulation, however, ectopic expression of AmRosea1 alone clearly upregulated expression of the main structural genes as well as greatly promoted anthocyanin accumulation in transformed hairy roots, where the contents reached 0.773–2.064 mg/g fresh weight. These results suggest that AmRosea1 plays a key role in the regulatory network in controlling the initiation of anthocyanin biosynthesis in roots, and the combination of AmRosea1 and hairy root culture is a powerful tool to study and production of anthocyanins in the roots of A. majus.

Study of growth characteristics of callus, suspension and root crops Scutellaria baicalensis

Scutellaria baicalensis is a popular traditional plant in Chinese medicine. Widely distributed biologically active substances of Scutellaria baicalensis are flavonoids (baicalin, baicalein, vogonin and vogonoside), which are responsible for the antitumor activity. Their antitumor effect is due to the absorption of oxidative radicals, the weakening of the activity of NF-kB (nuclear factor-kB), the suppression of the expression of the COX-2 gene and the regulation of the cell cycle. In addition, baicalein, baicalin, and vogonin showed strong antioxidant activity. The root culture in vitro of the medicinal plant Scutellaria baicalensis is characterized by intensive growth. The growth index at the end of the cultivation cycle was 40. The growth curve has a standard S-shape, with pronounced growth phases. The stationary phase was observed from 5-7 weeks of cultivation. The root culture growth index was 22.