Original article Elicitors act as a signal transducer in the enhancement of camptothecine production from in vitro cultures of Ophiorrhizamungos L

Abstract

Ophiorrhiza mungos L. is a member of Rubiaceae family, can be a gold standard for the in vitro production of high-value antica ncer compound, camptothecine (CPT) to meet the increasing market demand for medicine. The axillary bud and leaf explants were inoculated on Murashige and Skoog (MS) medium, fortified with different concentrations and combinations of plant growth regulators (PGRs) like N 6 -benzyladenine (BA), linetin (Kn) and indole-3 acetic acid (IAA). The best morphogenic response was observed on MS medium fortified with 8.87 µM l -1 BA, 4.65 µM l -1 Kn and 2.69 µM l -1 IAA, which exhibited the hundred percent regeneration frequency and maximum number of shoots from nodal and leaf explants (63.56 ± 0.28 and 45.03 ± 0.38, respectively) within four weeks. Fortification of 0.87 µM l -1 of gibberellic acid (GA 3 ) along with 4.44 µM l -1 BA enhanced shoots elongation by 7.06 ± 0.19 in 100% of shoot cluster cultures within four weeks. A high percent frequency of rooting (75%) was achieved within 15 days of shoot implantation on half strength MS medium fortified with 4.9 µM l -1 , indole-3-butyric acid (IBA). The rooted plantlets were successfully acclimatized with 100% survival rate in a growth chamber at 25°C, 60 % relative humidity, with 16 h photoperiod. The content of CPT (0.23% w/w) was significantly increased in regenerated plants treated with elicitors compare to the naturally grown plants. The present results evidently showed comparable chemical profile, suggesting that in vitro regenerated plants could be an alternative approach to obtain CPT. These in vitro regenerated flowering plants of O. mungos will be used by floral dip method for over expression of key genes involved in regulating terpenoidindole alkaloid (CPT) biosynthesis.

Biotechnological approaches for the production of camptothecin

“…Sonication is one of the most commonly used extraction methods. Camptothecin ranging from 0.85 to 3.6% and 0.15 to 0.23% has been extracted by sonication method from callus cultures of C. acuminata (van Hengel et al 1994) using 18 mL water and 20 mL dichloromethane solvent, and from O. mungos (Nagesha et al 2018) using 50 mL of methanol, respectively. 0.014% and 0.008-0.0096% of CPT were extracted from cultures of O. mungos (Krishnan et al 2018) and rugosa var.…”