Plant Cell, 1issueand OrganCulture 42:117-119, 1995. 117 © 1995 KluwerAcademicPublishers. Printedin thi Netherlands. Research Note Rapid propagation of tuna (Opuntiaficus-indica) and plant establishment in soil Yasseen Mohamed-Yasseen 1, Sheryl A. Barringer 2, Walter E. Splittstoesser I & Raymond J. Schnell 3 1University of Illinois, Dept. of Horticulture, S-406 Turner Hall, l l02 S. Goodwin Ave., Urbana, IL 61801, USA; 2Ohio State University, Dept. of Food Sci & Tech., 122 Vivian Hall, 2121 Fyffe Rd., Columbus, 0H43210-1097, USA; 3USDA, ARS, Nat. Clonal Germplasm:Rep., 13601 Old Cutler Rd., Miami, FL 33158 Received 1 February 1994;acceptedin revised form21 April 1995 Key words: Cactus, prickly pear, micropropagation, Indian fig, organogenesis Abstract Explants from young joints of mature plants of tuna (Opuntiaficus-indica Mill.) were cultured on Murashige and Skoog (MS) medium containing 8.8 #M benzyladenine (BA) and 0.5 #M naphthaleneacetic acid (NAA). Shoots produced were utilized as secondary explants. Each shoot was cut longitudinally from apex to base into two explants, and some of these explants were cut transversely into proximal and distal explants. The size and number of shoots produced was affected by size and position of the explant within its source. The shoots were rooted in vitro or ex vitro and plants were successfully established in soil from both rooting methods. Abbreviations: AC - activated charcoal, BA - benzyladenine, IBA- indolebutyric acid, MS - Murashige & Skoog (1962) medium, NAA - naphthaleneacetic acid. Prickly pear cactus or tuna (Opuntiaficus-indica Mill.) has been used as food for centuries and is grown com- mercially in Mexico, the Mediterranean area, Aus- tralia and south-western USA (Mohamed-Yasseen et al. 1995). Its fruits are consumed fresh or made into candy. Plants are succulent with jointed, branching stems. These stems, or joints, are often cooked as a green table vegetable (Russell & Felker 1987). Spine- less joints, and those burned to remove spines, are used as livestock forage. Tuna has a high potential as a horti- cultural crop, especially in areas where drought limits production of more common fruits or forage crops. However, few attempts have been made to improve the species characteristics or its nutritive value. The effect of different growth regulators on the morpho- genesis of Opuntia polycantha, a non-edible Opun- tia, has been determined (Mauseth & Halperin .1975; Mauseth 1976) and a method for propagation of Opun- tia has been reported (Escobar et al. 1986). Presently, there is no information available about micropropa- gation of Opuntia ficus-indica, which is considered to have the most important edible fruits in the Cac- taceae (Mohamed-Yasseen et al. 1995). Tuna can be grown from seed, but this presents three main prob- lems: genetic segregation, a long juvenile stage and the slow growth of seedlings compared to asexually propagated material (Mohamed-Yasseen et al. 1995). These problems can be overcome by micropropaga- tion. This paper presents a method for micropropaga- tion and successful plant establishment in soil. Young stems were taken from branched mature plants (14-16 cm long) and were washed thorough- ly with water and 2% detergent (Alconox), surface disinfested in 0.3% (v/v) sodium hypochlorite for 10 min, then rinsed three times in sterile distilled water. Surface disinfested joints were cut into explants (10 mm 3) each containing one areole. In some cases, the; explants were bisected through the stem pith into two equal segments, and the segment containing the are- ole was cultured. These explants were cultured on MS