In Vitro Regeneration from Longitudinal Sections of Seedlings of Beaucarnea purpusii Rose, an Endemic and Endangered Species

Abstract

The present study establishes an efficient protocol for in vitro propagation from longitudinal sections of seedlings of Beaucarnea purpusii, a threatened and highly appreciated ornamental species. The effect of three cytokinins: N6-benzyladenine (BA), kinetin (Kin), and thidiazuron, 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea (TDZ), in semisolid media and three different concentrations, as well as the effect of BA and TDZ pulses at higher concentrations in liquid culture medium, were investigated. Adventitious shoot formation by direct organogenesis was observed from all treatments. Additionally, adventitious shoot formation was recorded from the leaves of the new shoots; this particular response was exclusive to treatments supplemented with TDZ. In the experiment using semisolid culture media, the highest means of shoots per explant were obtained from treatments containing TDZ, particularly at a concentration of 0.45 μm (25.8 shoots per explant). For the pulses experiment, the liquid culture media supplemented with TDZ at 22.35 µm for 24 hours and 136.21 µm for 96 hours, induced a mean of 3.9 and 3.3 shoots per explant, respectively. Subculturing individual shoots on MS and half-strength MS (1/2MS) media, both supplemented with activated charcoal at 1 g·L−1, induced rooting in 85% to 95% of shoots. A survival rate of 100% under greenhouse conditions was achieved. The results of this study provide an efficient alternative for mass propagation of B. purpusii and may also contribute to the conservation and sustainable use of this valuable natural resource.