Hairy roots

Bohm, H. and Mack, G., Betaxanthin formation and free amino acids in hairy roots of Beta vulgaris var. lutea depending on nutrient medium and glutamate or glutamine feeding. Phytochemistry 65, 1361, 2004. 

Hempel, J. and Bohm, H., Betaxanthin pattern of hairy roots from Beta vulgaris var. lutea and its alteration by feeding of amino acids. Phytochemistry, 44, 847, 1997. 

Decarboxybetaiudin, the glucoside of which was reported recently in hairy root cultures of yellow beet, may be synthesized from dopamine. Two further alternatives were proposed earlier. While Minale and co-workers subjected betanin... 

Kwok, K. H., and Doran, P. M., Kinetic and Stoichiometric Analysis of Hairy Roots in a Segmented Bubble Column Reactor, Biotechnol. Prog., 11 429 (1995)... 

Foreign Protein Expression Using Plant Cell Suspension and Hairy Root Cultures... 

Most research into in vitro foreign protein production has been undertaken using cell suspensions. However, other forms of plant tissue culture such as hairy roots and shooty teratomas have also been tested in a number of studies (Table 2.1). The characteristics of different types of plant tissue culture and their utility for large-scale foreign protein production are outlined in the following sections. 

Cytochrome P450 2E1, rabbit Hairy root Atropa belladonna A. rhizogenes transformation of leaf explant CaMV 35S Not reported Not reported 22... 

Green fluorescent protein Hairy root Hyoscyamus muticus A. tumefaciens transformation CaMV 35S - Not reported 23... 

Antibody, murine Hairy roots Nicotiana tabacum 2 L, magnetic stirrer, 1.9 mg L-1 (e) 19... 

Fig. 2.1 Root growth (O) and accumulation of tobacco mosaic virus (TMV) ( ) in hairy roots of N. benthamiana. TMV concentrations were measured by ELISA. The error bars indicate standard errors from four replicate shake-flask cultures.

The presence of foreign protein in the medium of plant cultures does not necessarily mean that all or even most of the product can be recovered from the medium. In many expression systems where an appropriate signal sequence has been used, considerable amounts of foreign protein remain within the plant cells and/or tissues. For example, in a comparison of IgG antibody production in tobacco cell suspension and hairy root cultures, a maximum of 72% of the total antibody was found in the medium of the suspension cultures whereas only 26% was found in the medium of the hairy root cultures [17]. This result could indicate that secretion and/or transport across the cell wall was slower in the hairy roots alternatively, it could indicate poorer stability of the secreted protein in the hairy root medium. If foreign proteins are to be purified from the medium, improved secretion and extracellular product stability are desirable. 

Increasing concentrations of PVP 360,000 up to 1.0 g L 1 improved antibody accumulation in hairy root culture medium however, above this concentration there was no further increase in antibody levels [19]. Addition of PVP after extracellular foreign protein levels had decreased during plant suspension culture did not result in a recovery of the protein [66]. 

Supplementation of Gamborg s B5 medium with 0.1% KN03 (in addition to the 0.25% KN03 usually present in B5 medium) resulted in a significant increase in antibody levels in tobacco hairy root cultures [19]. The antibody concentration in the medium increased 2.8-fold and the total antibody accumulation increased by 90% relative to cultures without added nitrate. 

Solution pH has a strong influence on the structure, conformation and solubility of globular proteins. However, when IgO, antibody was added to fresh, sterile B5 medium adjusted to pH values between 4.0 and 8.0, there was no significant difference in the rate at which the antibody disappeared from the different solutions [63]. In other work, antibody-expressing tobacco hairy roots were cultured in B5 medium with initial pH between 3.0 and 11.0 [69]. Root growth was affected severely at the lowest and highest pH values and total antibody levels declined as the initial pH was increased above 5.0-6.0. 

In transgenic hairy root cultures, the concentration of IgG antibody in the biomass increased by 52% relative to the levels obtained under air when the roots were cultured at a dissolved oxygen tension of 150% air saturation [17]. Compared with root cultures grown at 50% air saturation, which is a realistic operating dissolved oxygen tension in poorly mixed, large-scale root reactors, oxygen enrichment to 150% air saturation improved total antibody accumulation 2.9-fold. 

R. Wongsamuth, P. M. Doran, Hairy roots as an expression system for production of antibodies, in Hairy Roots Culture and Applications, ed. P. M. Doran, Harwood Academic, Amsterdam, 1997, 89-97. 

RicinB fused to green fluorescent protein (GFP) Tobacco leaf and hairy root culture GFP-specific IgG present in serum IgA in semm and fecal matter. 10... 

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