BIOLOGIA PLANTARUM 49 (1): 29-33, 2005 29 Direct somatic embryogenesis and plant regeneration from ray florets of chrysanthemum A.K.A. MANDAL and S.K. DATTA* Floriculture Section, National Botanical Research Institute, Lucknow-26001, U.P., India Abstract Direct somatic embryogenesis from ray floret explants of five chrysanthemum cultivars has been obtained within 12 - 15 d on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA). Scanning electron microscopic observation also confirmed the direct origin of somatic embryos from explants. Somatic embryos developed asynchronously on the adaxial surface of explants. Among the five cultivars tested, Birbal Sahani was best responding (40 % explants responded on 4 mg dm -3 2,4-D and 2 mg dm -3 BA supplemented medium). Precocious germination of somatic embryos was noticed on the same medium. The best sucrose concentration in the medium was found to be 60 g dm -3 where 70 % explants responded while 55 % embryogenic response was obtained on medium supplemented with 400 mg dm -3 inositol. Plants developed from somatic embryos were transferred to soil and produced true-to-type flowers. Additional key words: 6-benzyladenine, Chrysanthemum morifolium, cultivar differences, 2,4-dichloro-phenoxyacetic acid, naphthaleneacetic acid. Introduction Flower colour/shape mutations mostly appear as chimeras. Isolation of mutant tissue is possible through conventional methods when entire branch is mutated. It was almost impossible to isolate through available conventional technique when a sector of a flower is mutated. A large number of new flower colour/shape chimeric tissues were being lost because of the unavailability of conventional microtechniques for management of such chimeric tissues. Recently, a novel technique has been standardized in our laboratory for the management of such chimeric tissues through direct shoot organogenesis from flower petals (Chakrabarty et al. 1999, 2000, Datta et al. 2001). It has solved the chimeric problem and new mutants have been established in chrysanthemum (Chakrabarty et al. 1999, 2000, Mandal et al. 2000a,b, Datta et al. 2001). Shoot bud have multiple cell origin whereas somatic embryo originates from single cell (Haccius 1978, Maheswaran and Williams 1985, Mandal and Dutta Gupta 2003). There is an urgent need to regenerate plants from a single cell, i.e. through somatic embryogenesis for management of single cell mutation event. The present paper reports an efficient somatic embryogenesis protocol in chrysanthemum. Materials and methods Ray florets of Chrysanthemum morifolium Ramat. cv. Purnima were collected from field grown plants. Ray florets were then washed in tap water with liquid detergent (5 %). Then ray florets were dipped in 70 % ethanol for 30 s followed by 0.1 % HgCl 2 for 2 min and washed thoroughly in sterile distilled water. Ray florets were cut transversely into two pieces and were used as explants. All the explants were cultured on the Murashige ⎯⎯⎯⎯ Received 18 September 2003, accepted 11 August 2004. Abbreviations: BA - 6-benzyladenine; 2,4-D - 2,4-dichlorophenoxyacetic acid; MS - Murashige and Skoog; NAA - naphthaleneacetic acid. Acknowledgements: The authors are thankful to the Director, National Botanical Research Institute, Lucknow, for providing facilities. * Author for correspondence; fax : (+91) 0522 2205836, e-mail: subodhdatta@usa.net