Indian Journal of Biotechnology Vol 6, July 2007, pp 381-384 In vitro propagation of Dendrobium microbulbon A. RichA rare ethnomedicinal herb Urvashi Sharma, V Rama Rao, J S S Mohan* and A S Reddy Post Graduate Department of Biosciences, Sardar Patel University, Vallabh Vidyanagar 388 120, India Received 27 February 2006; revised 26 September 2006; accepted 19 December 2006 Dendrobium microbulbon A. Rich (Orchidaceae) is a small epiphytic rare orchid used in stomachache by the tribal people of Gujarat. The present study deals with the development of a suitable protocol for its clonal propagation using pseudobulbs as explants. Murashige and Skoog (MS) basal medium supplemented with various concentrations of auxin and cytokinin was used either alone or in combination for induction, multiplication, elongation and rooting of in vitro shoots. MS medium fortified with 3% sucrose, 7.5 mg L -1 indole-3-acetic acid (IAA) and 20 mg L -1 benzyl aminopurine (BAP) showed axillary bud initiation. MS medium with 2.0 mg L -1 BAP favoured production of maximum number of shoots (39 shoots), elongation of shoots as well as bulblets formation. In vitro raised shoots were rooted on Knop salts with MS vitamins and MS iron salts. During acclimatization, 60% of the plantlets survived after their removal from in vitro conditions. Keywords: conservation, in vitro flowering, secondary explants, shoot multiplication, pseudobulbs, Dendrobium microbulbon IPC code: Int. Cl. 8 A01H4/00, 5/04 Introduction In ancient Indian literature, orchids are mentioned as medicinal and aromatic plants. They are associated with folk songs and festive dances. They have been used for their therapeutic value all over the world owing to their phytoconstituents such as alkaloids, flavonoids, terpenes and glycosides 1 . Though orchids produce a large number of seeds, very few (< 5%) of them germinate under natural conditions because the seeds are non-endospermic, minute and require a mycorrhizal association 2 . The conventional method of vegetative propagation of orchids is a time consuming and tedious process 3 . During the last few years, tissue culture methods have been extensively exploited for rapid and large-scale propagation of a number of orchid species 2, 4-6 . Dendrobium microbulbon A. Rich is a small orchid, found as an epiphyte on Tectona grandis L. f., Mangifera indica L. and Madhuca indica J. F. Gmel et al, and mostly distributed in Dangs, Vansada and Rajpipla forest regions of Gujarat 7 , and in Konkan, Western Ghats, Uttara Kannada, Nilgiris and Annamalai forests of Tamil Nadu 8 . It is kept in the indeterminate category according to the World Conservation Monitoring Centre (WCMC). The ecological measures on this rare species are relatively minimized. According to the tribal people of Gujarat, crushed leaves applied on stomach cures stomachache 7 and the bulbs are edible 9, 10 . Other species of Dendrobium viz. D. ovatum (Willd.) 10 and D. macrael Lindl. 11 have wide usage in medicines as a tonic. Reports of mass propagation of D. macrostachyum Lindl. 12 and D. moschatum (Buch-Ham) Watz 13 are available. According to our knowledge, no report exists on direct regeneration of shoots from pseudo- bulbs and in vitro flowering of D. microbulbon. In the present study, an attempt has been made to develop a method for rapid clonal propagation of this rare ethnomedicinal herb for its conservation and reintroduction into its natural habitat. Materials and Methods Pseudobulbs (Fig. 1a) of Dendrobium microbul- bon were collected during April-May from the Dangs forest, South Gujarat, India and used as explants. ____________ *Author for correspondence: Tel: 91-2692-234412 ext. 210 E-mail: jssmohan@hotmail.com