Elicitation Based Enhancement of Secondary Metabolites in Rauwolfia serpentina and Solanum khasianum Hairy Root Cultures

BACKGROUND: Rauwolfia serpentina and Solanum khasianum are well-known medicinally important plants contained important alkaloids in their different parts. Elicitation of these alkaloids is important because of associated pharmaceutical properties. Targeted metabolites were ajmaline and ajmalicine in R. serpentina; solasodine and α-solanine in S. khasianum. OBJECTIVE: Enhancement of secondary metabolites through biotic and abiotic elicitors in hairy root cultures of R. serpentina and S. khasianum. MATERIALS AND METHODS: In this report, hairy root cultures of these two plants were established through Agrobacterium rhizogenes mediated transformation by optimizing various parameters as age of explants, duration of preculture, and co-cultivation period. NaCl was used as abiotic elicitors in these two plants. Cellulase from Aspergillus niger was used as biotic elicitor in S. khasianum and mannan from Saccharomyces cerevisiae was used in R. serpentina. RESULTS: First time we have reported the effect of biotic and abiotic elicitors on the production of important metabolites in hairy root cultures of these two plants. Ajmalicine production was stimulated up to 14.8-fold at 100 mM concentration of NaCl after 1 week of treatment. Ajmaline concentration was also increased 2.9-fold at 100 mg/l dose of mannan after 1 week. Solasodine content was enhanced up to 4.0-fold and 3.6-fold at 100 mM and 200 mM NaCl, respectively, after 6 days of treatments. CONCLUSION: This study explored the potential of the elicitation strategy in A. rhizogenes transformed cell cultures and this potential further used for commercial production of these pharmaceutically important secondary metabolites. SUMMARY: Hairy roots of Rauwolfia serpentina were subjected to salt (abiotic stress) and mannan (biotic stress) treatment for 1 week. Ajmaline and ajmalicine secondary metabolites were quantified before and after stress treatment. Ajmalicine yield was enhanced up to 14.8-fold at 100 mM concentration of NaCl. Ajmaline content was also stimulated 2.9-fold at 100 mg/l dose of mannan after 1 week. Hairy roots of Solanum khasianum were treated with cellulase (biotic elicitor) and salt (abiotic stress). Solasodine content was improved up to 4.0-fold and 3.6-fold at 100 mM and 200 mM NaCl, respectively, after 6.days of treatments. The α-solanine content increased to 1.6-fold after 24 h of treatment at 100 μg/mL cellulase concentration. Abbreviations used: MS medium: Murashige and Skoog medium, B5 medium: Gamborg B5 medium, OD: Optical Density, NaCl: Sodium Chloride.