In vitro propagation of three endangered cactus species

We tested the feasibility of in vitro culture techniques for the propagation of the three endangered cacti species Escobaria minima (Baird)D. Hunt, Mammillaria pectinifera (Ruempler)F.A.C.Weber and Pelecyphora aselliformis Ehrenberg. Twenty-five MS-based proliferation media were tested in preliminary experiments, with different combinations of the auxin NAA and either of the cytokinins BA, kinetin or TDZ. TDZ induced a good proliferation rate, albeit associated with abundant callus formation and hyperhydricity of axillary shoots. A high multiplication rate combined with good quality proliferated shoots and little or no callus induction was observed on media containing BA for E. minima and M. pectinifera and on a medium containing kinetin for P. aselliformis. These results were also confirmed in subsequent experiments in which different explants (shoot tips, bases and longitudinal sections)were used. Micropropagated plantlets were successfully restored to the field, where they reached the flowering stage. Plantlet regeneration of M. pectinifera and P. aselliformis from callus induced on media containing TDZ, but not 2,4-D, was also achieved.