EFFECT OF GROWTH REGULATORS ON THE ORGANOGENESIS AND MULTIPLICATION OF ORTEGOCACTUS MACDOUGALLII ALEXANDER

Ortegocactus macdougallii is highly appreciated ornamental and endemic Mexican cactus recently classified as a threatened plant species by the Government of Mexico. In order to rescue this plant from the risk of extinction and because conventional systems produce low propagation rates, we established a reliable and efficient method of micropropagation based in tubercle culture. During the establishment stage, varies concentracions of the combination of NAA (1.3, 4.4, and 13.3 mu M) and BA (1.3, 4.4, and 13.3 mu M) induced callus and shoot formation when explants (tubercles and axillary meristems or areoles dissected from adult plants) were incubated on Murashige and Skoog medium. In adition to this, the NAA free variants of the medium stimulated the rooting during the establishment stage, in particular the treatments including low and medium concentrations of BA (1.3 and 4.4 p,M). During shoot proliferation, treatments including NAA (4.4 mu M) and BA at 13.3, 19.9 or 26.6 mu M produced between 5 and 6 shoots per explant; however, shoots obtained on medium with NAA 4.4 and BA 13.3 M were statistically higher (5 mm). Rooting was produced on quarter- or half-strength MS medium but half-strength MS medium supplemented with IBA (1.6 or 4.9 mu M) resulted in higher percent of rooted shoots (75%) and mean root number (8).