BIOLOGIA PLANTARUM 48 (1): 13-18, 2004 Rapid in vitro regeneration of Sesbania drummondii S.B. CHEEPALA, N.C. SHARMA and S.V. SAHI* Biotechnology Center, Department of Biology, Western Kentucky University, Bowling Green, KY 42101 USA Abstract This paper describes rapid propagation of Sesbania drummondii using nodal explants isolated from seedlings and young plants. The nodal segments proliferated into multiple shoots on Murashige and Skoog’s (MS) medium supplemented with 22.2 µM benzyladenine. MS medium containing 2.2 and 4.5 µM thidiazuron induced 5 - 6 shoots per stem node from 3-month-old plants. Nodal explants when cultured on MS medium containing combinations of benzyladenine (8.8 and 11.1 µM) and indole-3-butyric acid (0.24 - 2.46 µM) or indole-3-acetic acid (0.28 - 2.85 µM) gave lesser number of shoots. Callus induced on cotyledonary explants when subcultured on 2.2 µM thidiazuron containing medium resulted in its mass proliferation having numerous embryoid-like structures. Indole-3-butyric acid (0.24 - 2.46 µM) was found suitable for root induction. In vitro regenerated plants were acclimatized in greenhouse conditions. Additional key words: 6-benzyladenine, indole-3-acetic acid, indole-3-butyric acid, medicinal plant, metal hyperaccumulator, micropropagation, thidiazuron. Introduction Sesbania drummondii (Rydb.) Cory (Fabaceae) is a perennial shrub. It is distributed in seasonally wet places of southern coastal plains of the United States of America, from Florida to Texas. Seed extracts of this plant are significantly active against lymphocytic leukemia P-388 in vivo. This was attributed to the presence of medicinally important alkaloids: sesbanimide and sesbanine (Powell and Smith 1981). Besides being a source for the various pharmaceutically valuable compounds, Sesbania drummondii is a hyperaccumulator of toxic heavy metals like lead, copper and zinc (Sahi et al. 2002). Of a wide range of Sesbania species, in vitro regeneration protocols have been developed for S. rostrata (Vlachova et al. 1987), S. sesban (Khattar and Mohan Ram 1982, Harris and Puddephat 1989, Zhao et al. 1993), S. grandiflora (Khattar and Mohan Ram 1983, Shanker and Mohan Ram 1990), S. cannabina (Xu et al. 1984, Shahana and Gupta 2002), S. bispinosa (Kapoor and Gupta 1986, Sinha and Mallick 1991). In these species, plant regeneration has been obtained by enhanced axillary branching as well as callus-mediated organogenesis from seedling explants and greenhouse grown plant-parts. There is no systematic cultivation of this plant and no published reports on tissue cultures of Sesbania drummondii are available. Therefore, there is a need to develop a means for rapid regeneration of plantlets. The present study thus focuses on in vitro morphogenesis and plant regeneration using various seedling explants such as cotyledonary node, axillary branch node, hypocotyl, epicotyl, cotyledon, and stem segments from greenhouse-grown plants. Materials and methods Seeds of Sesbania drummondii were scarified using 85 % H 2 SO 4 for 30 min followed by washing under running tap water for 1 h. Seeds were sterilized with 0.2 % HgCl 2 and then transferred to magenta boxes containing water-agar ⎯⎯⎯⎯ Received 3 March 2003, accepted 15 January 2004. Abbreviations: BA - 6-benzyladenine; IAA - indole-3-acetic acid; IBA - indole-3-butyric acid; NAA - α-naphthaleneacetic acid; TDZ - thidiazuron; MS medium - Murashige and Skoog’s (1962) medium. Acknowledgements: Authors wish to acknowledge the Biotechnology Center, the Department of Biology and Western Kentucky University for their financial support. * Corresponding author; fax: (+1) 270 745 6856. e-mail: shiv.sahi@wku.edu. 13