Journal of Tropical Biology and Conservation 11: 33–40, 2014 ISSN 1823-3902 Published 2014-10-15 Studies of sterilization protocol development and calli induction of selected tropical mosses Makinde A.M., Isa M.O.*, Ayisire B.E. Botany Department, Obafemi Awolowo University Ile-Ife, Nigeria *Corresponding author: alamuola25@gmail.com Abstract Four tropical African mosses namely; Racopilum africanum, Thuidium gratum, Archidium ohioense and Bryum coronatum, were studied. This was with a view to developing a sterilization protocol and inducing calli from the gametophyte explants in vitro. The mosses were collected from their natural populations in the Central Campus of the Obafemi Awolowo University, Ile-Ife, Nigeria. Healthy stem tips from the gametophytes of each of the mosses were sterilized with JIK (containing 3.85 % M/V NaOCI) and then cultured on Murashige and Skoog (MS) 1962 full strength medium, which served as the control and a full strength MS medium supplemented with 5 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D). Sterilization of the explants with 8 % JIK for 8 minutes was found to be most suitable. Only Bryum coronatum produced calli on hormone free medium, while the 2,4-D induced massive production of calli in Bryum coronatum and Racopilum africanum. Keywords: Explant, Calli, Gametophyte, 2,4-D, Sterilization Introduction Bryophytes are the second largest group of plants, comprising 15,000 – 25,000 species (Crum, 2001; Gradstein et al., 2001) and occur on every continent in every location habitable by photosynthetic plants. Propagation of bryophytes occurs both sexually and asexually (Makinde & Odu, 1993). Odu (1987), and Odu & Akinfenwa (1991) showed a great multiplicity of forms of vegetative propagules from which new generations of adult plants are often established on various substrates. Culture cells of bryophytes contain active chloroplasts and can grow under photoautotrophic conditions among green land plants (bryophytes, pteridophytes and seed plants) (Katoh, 1983). Axenic culturing of bryophytes seemed to be so complicated that many investigators gave up their attempts and thus, bryophytes did not retain for long their rightful place as a highly favoured research object. For this reason, most studies of plant morphogenesis are now being done on vascular plants Research Article