Optimized protocol for in vitro callus induction and micropropagation of Urena lobata L.: A fast-vanishing important medicinal plant
Farjana Ansari and Y. Vimala
Urena lobata (L.) is a valuable medicinal plant used widely in Ayurveda and Siddha to treat several ailments. Due to rapid urbanization, weeding, and excessive use of nitrogenous fertilizers, U. lobata population is dwindling, and it needs to be conserved to save the valuable medicinal resource. Thus, an optimized protocol has been developed for callus induction and micropropagation from the stem/leaf explants of U. lobata. Various growth regulators have been tested to achieve the best callus formation, such as 0 to 4 mg/l of 2,4-D, Kn, IAA, IBA, NAA, and BAP supplemented to MS medium individually and in combination. MS medium supplemented with 2,4-D with Kn and NAA with BAP in specific doses led to maximum callus initiation specially from stem explants rather than leaf explants. Callus could be successfully induced using 2.0 mg/l 2,4-D, 1.0 and 2.0 mg/l NAA individually or using 1 mg/l 2,4-D with 2.0 mg/l Kn or 1.0 mg/l NAA with 1.5-2.0 mg/l BAP in combination. There was no callus formation in control sets (without PGRs). Supplementation of MS medium individually with 2.0 mg/l IAA or even kinetin in the same dose resulted in maximum roots production (30% frequency) and shoots (66% frequency) from stem explants at 270C. After primary hardening, healthy plants were transferred to the greenhouse. Interestingly 20C modulation of temperature led to morphogenetic transformation to callus formation at 250C. Thus, callus or plantlet could be obtained strategically as per demand. Callus can also be used for upscaled production of bioactive secondary metabolites, helping protect the parent plant from overexploitation.