Polyamines Mediated In Vitro Morphogenesis in Cotyledonary Node Explants of Mucuna pruriens (L.) DC.: A Natural Source of L-Dopa

Mucuna pruriens (L.) DC. (Fabaceae) is considered as a remarkable medicinal plant and an excellent natural source of L-Dopa. Due to its medicinal values the present study was carried out to evaluate the efficiency of different polyamines, viz. putrescine, spermidine, and spermine, singly and in combination with other plant growth regulators for in vitro multiplication from cotyledonary node explants. Polyamines were further examined for in vitro root formation in regenerated shootlets. Among different combinations, Murashige and Skoog medium consisting of putrescine (10.0 mu M) with 6-benzyladenine (2.5 mu M) was found to be the most effective combination for obtaining the highest number of shoots (22.8) with most significant mean shoot length (6.04 cm) per explant in 85% cultures, after eight weeks. Rhizogenesis in regenerated shootlets was successfully achieved on half-strength MS medium containing putrescine (15.0 mu M) with indole-3-butyric acid (0.5 mu M). On this media, the highest mean numbers of roots (4.5) with mean root length (3.8 cm) per microshoot were recorded in 95% of cultures, after four weeks. Analysis of glutathione-S-transferase activity indicated that the polyamines-mediated cultures revealed the lowest amount of toxic agents. This activity is substantial to evaluate the level of detoxification in plant tissues during in vitro culture conditions. During the hardening and acclimatization period, the photosynthetic pigments were initially fluctuating, and thereafter a gradual increasing trend was observed. Finally, well-acclimatized regenerated plantlets were transferred to the field, where they grew normally without any phenotypic variation with a 90% survival rate after eight weeks. Genetic fidelity among regenerants was validated by DNA fingerprinting using inter simple sequence repeats markers.