Thidiazuron (TDZ) induced plant regeneration from cotyledonary petiole explants of elite genotypes of Jatropha curcas: A candidate biodiesel plant

Jatropha curcas, the energy plant has attained great attention in recent years because of its biodiesel production potential and medicinal value. This makes it imperative to search for techniques for its rapid propagation. In the present investigation an efficient and reproducible method for plant regeneration through direct shoot bud induction from cotyledonary petiole explants of elite genotypes (CSMCRI-JC-1, CSMCRI-JC-2 and CSMCRI-JC-3) of J. curcas was developed. The best shoot buds induction (51.19%) and number of shoot buds (9.75) per explant was observed when in vitro petiole explants were placed horizontally on MS medium supplemented with 2.27μM TDZ after 6 weeks. The induced shoot buds were transferred to MS medium containing 10μM kinetin (Kn), 4.5μM 6-benzyl aminopurine (BAP) and 5.5μM α-naphthaleneacetic acid (NAA) for shoot proliferation. The proliferated shoots could be elongated on MS medium supplemented with different concentrations and combinations of BAP, indole-3-acetic acid (IAA), NAA and indole-3-butyric acid (IBA). MS medium with 2.25μM BAP and 8.5μM IAA was found to be best combination for shoot elongation and 3.01–3.61cm elongation was achieved after 6 weeks. However, significant differences in plant regeneration and shoot elongation were observed among the genotypes studied. Orientation (horizontal or vertical) and source (in vitro or in vivo) of explants also significantly influenced plant regeneration. The elongated shoots could be rooted on half-strength MS medium supplemented with 0.25mg/L activated charcoal and different concentrations and combinations of IBA, IAA and NAA. Half strength of MS medium with 5μM IBA, 5.7μM IAA and 11μM NAA was found to be best for rooting. The rooted plants could be established in soil with more than 90% survival rate.