BIOLOGIA PLANTARUM 52 (4): 743-748, 2008 743 BRIEF COMMUNICATION In vitro regeneration of Leucaena leucocephala by organogenesis and somatic embryogenesis S. RASTOGI 1 *, S.M.H. RIZVI 2 **, R.P. SINGH 2 and U.N. DWIVEDI 3 Department of Biotechnology, Integral University, Lucknow-2260026, India 1 Department of Biosciences, M.D. University, Rohtak, Haryana, India 2 Department of Biochemistry, Lucknow University, Lucknow, India 3 Abstract In the present study, in vitro regeneration system for a recalcitrant woody tree legume, Leucaena leucocephala (cvs. K-8, K-29, K-68 and K-850) from mature tree derived nodal explants as well as seedling derived cotyledonary node explants was developed. Best shoot initiation and elongation was found on full-strength Murashige and Skoog (MS) medium supplemented with 3 % (m/v) sucrose, 100 mg dm -3 myoinositol, 100 mg dm -3 glutamine, 20.9 μM N 6 -benzylamino-purine (BAP) and 5.37 μM 1-naphthalene acetic acid (NAA). Rooting was induced in half-strength MS medium containing 2 % (m/v) sucrose, 100 mg dm -3 myoinositol, 14.76 μM indole-3-butyric acid (IBA) and 0.23 μM kinetin. The cultivar K-29 gave the best response under in vitro conditions. Rooted plantlets were subjected to hardening and successfully transferred to greenhouse. Further, somatic embryogenesis from nodal explants of cv. K-29 via an intermittent callus phase was also established. Pronounced callusing was observed on full-strength MS medium containing 3 % (m/v) sucrose, 100 mg dm -3 myoinositol, 40.28 μM NAA and 12.24 μM BAP. These calli were transferred to induction medium and maximum number of globular shaped somatic embryos was achieved in full- strength MS medium fortified with 3 % (m/v) sucrose, 100 mg dm -3 myoinositol, 15.0 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 5.0 μM BAP and 1.0 mM proline. Moreover, an increase in endogenous proline content up to 28 th day of culture in induction medium was observed. These globular shaped somatic embryos matured in full-strength MS medium with 3 % (m/v) sucrose, 100 mg dm -3 myoinositol, 10.0 μM BAP, 2.5 to 5.0 μM IBA and 0.5 mM spermidine. Additional key words: callus, root induction, shoot formation and multiplication, subabul, tissue culture, tree legume. ⎯⎯⎯⎯ Leucaena leucocephala (Fabaceae), commonly known as subabul, is a commercially valuable multipurpose tree with tremendous applications as forage, raw material for pulp and paper industry, timber, firewood, fuel, gum, organic fertilizer and depilatory agent (Rastogi and Dwivedi 2003, 2008). The conventional methods of vege- tative propagation for the tree are unsatisfactory owing to hard seed coat, low seed viability and long period between successive generations. Moreover, regeneration of forest trees in general and legumes in particular has been a formidable problem. Although attempts directed towards tissue culture of L. leucocephala have been made, of these only a few deal with micropropagation but with low survival rate, while others report only shoot regene- ration or plantlet regeneration with a weak root system (for review see Mascarenhas and Muralidharan 1989, Rastogi and Dwivedi 2003). The present paper describes a simple, efficient and reproducible system for organo- genesis and somatic embryogenesis in L. leucocephala. Leucaena leucocephala (Lam.) de Wit cvs. K-8, K-29, K-68 and K-850 growing in departmental garden were used for explant procurement. The juvenile shoots ⎯⎯⎯⎯ Received 6 February 2007, accepted 25 August 2007. Abbreviations: BAP - N 6 -benzylaminopurine; 2,4-D - 2,4-dichlorophenoxy acetic acid; IAA - indole-3-acetic acid; IBA - indole-3- butyric acid; MS medium - Murashige and Skoog medium; NAA - 1-naphthalene acetic acid. Acknowledgements: Financial supports in the form of a research project from the Department of Biotechnology, India, SRF to S.R. from Council of Scientific and Industrial Research, India and grants from Department of Science and Technology, India under the FIST program are gratefully acknowledged. ** Present addresses: ICRISAT, Hyderabad, India * Corresponding author; fax: (+91) 0522 2890730, e-mail: smita_rastogi@rediffmail.com