Influence of explant and plant growth regulators on callus mediated regeneration in Lavatera cashmeriana, Cambess

Plant growth regulators play a pivotal role in in vitro callus induction and callus growth habits and also determine the correlation of callus types with organogenesis for micropropagation purpose. Successful callus cultures of Lavatera cashmiriana were established in 7 explant types (root, node, petiole, leaf, petal, stamen and ovary) using auxins and cytokinins. Although, petal, anther and ovary explants were able to develop healthy friable callus even in hormone-free medium, highest callus induction % age, within 8-10 days was observed using auxins. 100% callus regeneration was observed in leaf explant followed by node (86.5%), petal (82%), ovary (78.5%), petiole (75.3%) and anther (75.1%) and the best growth substance for Callus induction was found to be 2, 4-D at the concentration of 2.0 mg/l. Using cytokinins+ auxins, the best percentage response of callus induction was obtained on BAP(1.0mg/l)+ NAA (1.0mg/l)) in leaf explants(83.5%) followed by petal (79.2%), node (74%), petiole (71%), ovary(61%) and stamen(39.8%) on the same hormonal concentration within 19-27 days. Two forms of callus growth habits were observed, friable and compact calluses. In NAA + Kn cultures, 100% friable callus was obtained while as high frequency of green, compact organogenic calli were obtained from leaf, node, petal and petiole explant, on BAP(2.0mg/l)+NAA(1.0mg/l) supplemented medium. The organogenic calli developed shoots in shoot regeneration medium and maximum (16) number of multiple shoots were developed on leaf callus in BAP(2.0mg/l)+NAA(1.0mg/l), followed by node callus (13) and petal(6).Comparative callusing and shoot regeneration from different explants revealed that leaf discs are the best explant for in vitro studies in L. cashmeriana. The best rooting (62%) response was observed in ½ MS (half strength of salt) + IBA1.5 mg/l. Finally the well rooted plantlets were hardened in plastic mini pots containing soil + sand + vermiculites (1:1:1) plantlets and then transferred to fields for acclimatization with a survival frequency of 68%. This protocol could be used to micropropagate L.cashmeriana for conservation. Also, the high frequency callus production potential of this prized plant can be utilized for commercial secondary metabolite production in pharmaceutical industry.