Transformed root (“hairy root”) cultures have been shown to be a good model for the study of many secondary metabolites. However, economically important compounds such as asiaticoside and madecassoside are produced in insignificant amounts in the root of Centella asiatica (L.) Urban. To overcome this problem, C. asiatica was transformed using Agrobacterium rhizogenes strain R1000 that harbors pCAMBIA1302 encoding the hygromycin phosphotransferase (hpt) and green fluorescence protein (mgfp5) genes and the hairy culture was coupled with elicitation technique. Hairy roots were obtained at a frequency of up to 14.1% from a tissue junction between the leaf and petiole. Abundant hairy roots were observed when co-cultivation of the plant with A. rhizogenes was done for 7 days (36.1%). Transformation was confirmed by PCR and Southern blot analyses. Five weeks after inoculation, no asiaticoside was detected in the hairy root samples. However, when 0.1 mM methyl jasmonate (MJ) was applied as an elicitor to the culture medium for 3 weeks, a large quantity of asiaticoside was generated (7.12 mg/g, dry wt). In the case of gene expression, 12 h after MJ treatment the expression of the CabAS (C. asiatica putative β-amyrin synthase) gene in the hairy roots is significantly different from that of the control and this level of transcripts was maintained for 14 days. Our results showed that production of C. asiatica hairy roots could be optimized and the resulting cultures could be elicited with MJ treatment for enhanced production of asiaticoside.

Enhanced production of asiaticoside from hairy root cultures of Centella asiatica (L.) Urban elicited by methyl jasmonate

The effects of a number of different elicitors on asiaticoside production in whole plant cultures of Centella asiatica were studied, including yeast extract, CdCl2, CuCl2 and methyl jasmonate (MJ). Only MJ and yeast extract stimulated asiaticoside production—1.53 and 1.41-fold, respectively. Maximum asiaticoside production was achieved following treatment with 0.1 mM MJ (116.8 mg/l). The highest asiaticoside production (342.72 mg/l) was obtained after 36 days of elicitation in cultures treated with 0.1 mM MJ and 0.025 mg/l 1-phenyl-3-(1,2,3-thidiazol-5-yl)urea (TDZ). Interestingly, MJ not only stimulated the production of asiaticoside but also had an important role in the senescence of C. asiatica. Although asiaticoside content did not change when TDZ was added to medium containing an elicitor, TDZ did increase shoot growth of C. asiatica. We discuss the interactive roles of MJ and TDZ in secondary metabolic production and biomass in whole plants of C. asiatica

Stimulation of asiaticoside accumulation in the whole plant cultures of Centella asiatica (L.) urban by elicitors

Centella asiatica (L.) is a perennial, creeper, faintly aromatic and a valuable medicinal herb of both Old World and the New World. It is distributed throughout tropical and subtropical regions of World such as India, China, Nepal, Madagascar, Srilanka and Indonesia etc. The requirement of Centella asiatica is now met from natural population, leading to their gradual depletion and thus followed by its placement in the list of threatened species as mentioned by IUCN. Much of the ancient and contemporary lore surrounding this plant with its chemistry and pharmacology related to efficacy of both herbal preparations and chemical isolates are justified on the basis of experimental evidences. This paper provides its immense importance as economic plant with medicinal value as well as brief information of its products in the market launched, showing its dependability.

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Centella asiatica (l.): a plant with immense medicinal potential but threatened

Comparative analysis of active constituents in Centella asiatica samples from Madagascar: Application for ex situ conservation and clonal propagation

Medicinal plants: An invaluable, dwindling resource in sub-Saharan Africa.

A protocol is described for rapid and large-scale in vitro clonal propagation of the valuable medicinal herb Centella asiatica (L) by enhanced axillary bud proliferation in nodal segments isolated from mature plants Although bud break was dependent on BA supply, the synergistic combination of 222 μM BA and 268 μM NAA induced the optimum frequency (91%) of shoot formation as well as shoot number (4 to 5 shoots per node) Subculturing of nodal segments harvested from the in vitro derived axenic shoots on the multiplication medium enabled continuous production of healthy shoots with similar frequency MS medium supplemented with 67 μM BA and 288 μM IAA was found most suitable for shoot elongation Rooting was highest (90%) on full-strength MS medium containing 246 μM IBA Micropropagated plants established in garden soil were uniform and identical to the donor plant with respect to growth characteristics This micropropagation procedure could be useful for raising a stock of genetically homogenous plant material for field cultivation

Nilesh Chandra Sharma

Papers

Micropropagation of Centella asiatica (L.), a valuable medicinal herb