In Vitro Propagation of Coryphantha macromeris

Abstract

Cacti are asexually propagated by offsets and cuttings or sexually via seeds (Johnson and Emino, 1979a). However, many species are slow-growing and do not produce offsets. Seeds are sometimes difficult to obtain (Mauseth, 1977) and seedlings are susceptible to damping-off (Mauseth, 1979). As onefourth of all cacti native to the United States are rare or in danger of extinction (Benson, 1977), in vitro propagation of cacti is an attractive alternative for multiplication and maintenance of valuable germplasm. Callus induction (Ault and Blackmon, 1987; Johnson and Emino, 1979a; Mauseth, 1977; Steinhart, 1962) and in vitro growth regulation (Mauseth and Halperin, 1975; Minocha and Mehra, 1974) have been investigated for some cacti species. Johnson and Emino (1979a, 1979b) reported successful in vitro propagation of Mammillaria elongata DC., Opuntia polyacantha Haw. P. and Hylocereus calcaratus (A. Berger) Britt & Rose. However, each cactus species required a different auxin: cytokinin balance for shoot induction (Johnson and Emino, 1979b). Ault and Blackmon (1987) reported in vitro shoot proliferation from Ferocactus acanthodes (Lemaire) Britt. & Rose. We describe an in vitro propagation method for Coryphantha macromeris (Engelm.) Lem. from callus culture. Seeds were surface sterilized in 1.05% (w/ v) NaOCl for 10 rein, rinsed in sterile water, and then aseptically germinated on Murashige and Skoog (1962) (MS) inorganic salts, pH 5.9, and solidified with 6 g Bacto agar/ liter. All cultures were maintained under a 24 μmol·s -1·m -2 light intensity (Sylvania Grow Lux wide spectrum fluorescent bulbs) for 16 h daily at 26 ± 3C. Shoot explants from the aseptically grown seedlings were cultured on MS medium supplemented with (per liter) 0.4 mg thiamine·HCI, 100 i-inositol, 20 g sucrose, 44