Micropropagação e criopreservação de Tabebuia roseoalba (Ridley) Sandwith e Cybistax antisyphilitica (Martius) Martius

Abstract

Plant tissue culture comprises techniques especially used for large-scale conservation and propagation, especially for plant species of economic, ornamental and medicinal importance. The objective was to establish a micropropagation and cryopreservation protocol for Tabebuia roseoalba and Cybistax antisyphilitica (Bignoniaceae). The first part presents a general introduction and a literature review on the species studied and the main tissue culture techniques employed in this work. In the second part, 4 articles are presented so that articles 1 and 2 deal with the in vitro multiplication of T. roseoalba and C. antisyphilitica, respectively. Prior to in vitro establishment, a germination test was performed with wingless, disinfested and inoculated seeds on MS medium with GA3. For induction of shoots in T. roseoalba, the explants consisted of nodal segments containing a pair of axillary buds, without the leaves. Subsequently, the rhizogenesiswas performed, followed by acclimatization. For germination and in vitro establishment of T. roseoalba the use of MS medium supplemented with 0.5 mg.L-1 of GA3is recommended for a germination above 80%. For broiler induction MS medium supplemented with a combination of BAP and KIN at 25 °C is recommended to obtain 3.5 shoots per explant. For rhizogenesis the use of MS medium supplemented with AIB 2.0 to 4.0 mg.L-1 and agar gel is recommended. For acclimatization, it is recommended the previous rooting of the shoots and the use of comercial substrate. For the induction of shoots in C. antisyphilitica, different explants were tested. Later, the shoots were rooted and acclimatized. For germination and in vitro establishment MS or MS½ medium is recommended, with no need for GA3. For induction of shoots in vitro the best explant was nodal segment containing a pair of axillary buds and without the leaves, excised of plants with 30 days of culture, and inoculated in MS medium with 8.0 mg.L-1 of BAP. For in vitro rooting MS medium is recommended, with 2.0 mg.L-1 of AIB. For acclimatization, transplanting of shoots should occur on comercial substrate. In article 3, the calogenic masses of both species were characterized. Thus, for calogenesis of C. antisyphilitica it is recommended hypocotyl or cotyledonary leaf as explants, inoculated in MS medium supplemented with 2.0 mg.L-1 of ANA. The growth curve of the calli in both species showed sigmoidal growth. In T. roseoalba there was a higher frequency of calli with brown color, whereas for calli of C. antisyphilitica the colorations were clearer. Callus darkening in both species was directly correlated to lipid peroxidation and callus viability. Callus of both species had low embryogenic potential under the conditions of this study. Finally, in article 4, the cryopreservation of seeds proved to be viable for the conservation of germplasm of both species. In spite of the indication of loss of viability through the Tetrazolium test, there was no change in the percentage and germination speed, percentage of normal seedlings and the survival of the plants to acclimatization.