Indian Journal of Biotechnology Vol 12, October 2013, pp 544-547 Callus induction and plant regeneration from leaf explants of jojoba [Simmondsia chinensis (Link) Schneider] Sunil Kumar 1,2 , Manisha Mangal 3 , A K Dhawan 4 and Narender Singh 2 * 1 Centre for Plant Biotechnology, CCS Haryana Agricultural University New Campus, Hisar 125 004, India 2 Department of Botany, Kurukshetra University, Kurukshetra 136 119, India 3 Central Institute of Post-Harvest Engineering and Technology, Ludhiana 141 001, India 4 CCS Haryana Agricultural University, Regional Research Station, Karnal 132 001, India Received 11 April 2012; revised 19 October 2012; accepted 18 January 2013 An efficient micropropagation protocol involving callus induction and shoot regeneration has been standardized in Simmondsia chinensis, an oil yielding, medicinal and multi- purpose plant species. Higher percent of callus proliferation (97.3%) was obtained from leaf explants, taken from field grown mature plant, when cultured on MS medium supplemented with 2,4-D (2.0 mg L -1 )+BAP (0.5 mg L -1 )+CH (100 mg L -1 ) within 20-22 d of inoculation. The callus was yellowish green in colour and soft in texture. Further, optimum shoot regeneration was obtained from the leaf derived callus on MS medium fortified with BAP (2.0 mg L -1 )+NAA (0.5 mg L -1 )+GA 3 (0.3 mg L -1 ). About 92% cultures responded with an average number of 9.1 shoots per culture. The shoots obtained via callogenesis were rooted on half-strength agar-solidified MS medium supplemented with IBA (1.0 or 2.5 mg L -1 ). The medium containing 2.5 mg L -1 IBA was the best for rooting of shoots. The rooted shoots were transplanted to soil with 75% success. The protocol will be of immense importance in rapid mass multiplication of elite germplasm, as well as for conservation of this important species. Keywords: Callus, in vitro propagation, jojoba, Simmondsia chinensis Simmondsia chinensis (Link) Schneider, commonly known as ‘jojoba’, is the sole species in the family ‘Simmondsiaceae’. The plant have deep root system, drought tolerant and can grow in semiarid regions and in acidic as well as alkaline conditions with a temperature range from -5° to 54ºC 1 . Jojoba is now cultivated commercially in Argentina, Egypt, India, Israel, Mexico, Peru, South Africa and the USA for its oil that makes up 50 to 55% of the seed weight 2 . Jojoba oil has been put to several diverse uses, such as, in antibiotic production, for cooking, hair care and for medical treatments of sores, wounds, colds, cancer, kidney malfunction and skin disorders, and in pharmaceuticals and cosmetics 3 . Owing to all these properties, Jojoba oil is described as one of the ‘nature’s gift to human race’ and ‘liquid gold from desert’. Availability of elite germplasm of this species has become an important issue and, therefore, development of efficient methods for mass multiplication of planting material is a high priority. Conventionally jojoba is propagated vegetatively by rooting semi-hard wood cuttings. However, this method provides only limited number of propagules, depending on size of plant and time of year 4 . Also, there are serious problems of male biased (5 male:1 female) population and setting of seeds after 3-4 yr of transplantation. Realizing these inherent problems, several efforts have been made to propagate jojoba in vitro on various culture media utilizing different regeneration pathways 5-6 . Indeed, micropropagation appears to be a robust technique for mass multiplication of jojoba and micropropagated plants of this species grow more vigorously than those obtained from seedling or rooted cuttings 7 . Further, micropropagation techniques ensure supply of desired plant material in abundant quantities and offers opportunities for the production of large- scale propagation of plants from the selected elite plant material in a short period of time. Hence, the present study was carried out to standardize a protocol for in vitro propagation of S. chinensis through culture of leaf segments and shoot regeneration from callus. The leaves obtained from field grown mature plant (~15-yr-old) of S. chinensis were washed with 5% teepol solution (10 min). Thereafter, the leaves were surface sterilized with 0.1% (w/v) mercuric chloride for 3 min, followed by a brief rinse with 70% ethanol and 2 to 3 washing with sterile distilled water under aseptic condition in laminar flow. The surface sterilized leaves were cut into small pieces (1 cm) and were placed in culture bottles containing 50 to 60 mL of agar —————— *Author for correspondence: E-mail: nsheorankukbot11@gmail.com Abbreviations: 2,4-D, 2,4-Dichlorophenoxyacetic acid; BAP, 6-Benzylaminopurine; CH, Casein hydrolysate; GA 3 , Gibberellic acid; IAA, Indole-3-acetic acid; IBA, Indole-3-butyric acid; Kn, Kinetin; NAA, -Naphthalene acetic acid