Micropropagation of 21 species of Mexican cacti by axillary proliferation

We have developed micropropagation systems for 21 species of Mexican cacti using explants from seedlings germinated in vitro or shoot segments of juvenile 2-3-yr-old greenhouse plants. The species propagated belong to the genera Astrophytum, Cephalocereus, Coryphantha, Echinocactus, Echinocereus, Echinofossulocactus, Ferocactus, Mammillaria, Nyctocereus, and Stenocactus. Multiple shoot formation from areoles was achieved in Murashige and Skoog (MS) medium supplemented with either 1 or 2 mg N⁶-benzyladenine (BA) per 1 (4.44 or 8.87 μM) or BA at 1 or 2 mg/l plus naphthaleneacetic acid at 0.1 or 1 mg/l (0.54 or 5.37 μM). The requirements of growth regulators for optimal shoot proliferation, the velocity of the response, and the number of buds produced by explant were different among the genera and species studied. Rooting of the shoots generated in vitro was achieved in MS medium supplemented with indoleacetic acid at 0.5-1 mg/l (2.85-5.71 μM) or indolebutyric acid at 0.5-1 mg/l (2.46-4.90 μM). Finally, 70-95% of the rooted plants transferred to potting medium survived.