Plant regeneration through the direct induction of shoot buds from petiole explants of Jatropha curcas: a biofuel plant

Abstract

An efficient and reproducible method for the regeneration of Jatropha curcas plants has been developed. The method employed direct induction of shoot buds from petiole explants, without the formation of an intervening callus using a Murashige and Skoog (MS) medium supplemented with different concentrations of thidiazuron (TDZ). The best induction of shoot buds (58.35%) and the number of shoot buds per explant (10.10) were observed when in vitro petiole explants were placed horizontally on MS medium supplemented with 2.27 µM TDZ after 6 weeks. The induced shoot buds were transferred to MS medium containing 10 µM kinetin (Kn), 4.5 µM 6‐benzyl aminopurine (BAP) and 5.5 µM 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 supplemented with 2.25 µM BAP and 8.5 µM IAA was found to be the best combination for shoot elongation and 3.01–3.91 cm elongation was achieved after 6 weeks. However, significant differences in plant regeneration and shoot elongation were observed among the genotypes studied. The 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 2% sucrose, different concentrations and combinations of IBA, IAA and NAA, and 0.25 mg L−1 activated charcoal. Half‐strength MS medium supplemented with 2% sucrose, 15 µM IBA, 5.7 µM IAA, 5.5 µM NAA and 0.25 mg L−1 activated charcoal was found to be the best for promoting rooting. The rooted plants could be established in soil with more than 90% survival.