Multiplicação e enraizamento in vitro de Handroanthus impetiginosus (Mart. Ex DC.) Mattos

This study aimed to evaluate cytokinin influence during in vitro multiplication stage and activated charcoal in combination with indole-3-butyric acid (IBA) during in vitro rooting of Handroanthus impetiginosus. For in vitro multiplication, nodal segments of shoots obtained from in vitro seedlings establishment were inoculated in Woody Plant Medium (WPM), with and without the following concentrations of 6-benzylaminopurine (BAP), kinetin (KIN) and thidiazuron (TDZ): 0.5; 1.0; 2.0; 4.0 and 8.0 µmol L-1. For in vitro rooting, shoots were inoculated in WPM containing combinations among IBA (1.0; 3.0; 6.0 and 9.0 μmol L-1) and activated charcoal (1.0; 2.0 and 3.0 g L-1), as well as their absence within culture medium. The highest number of shoots and buds was reached after using TDZ 8.0 μmol L-1, where in the best rooting occurred after adding activated charcoal 2.0 g L-1, regardless of IBA concentration. Our results show that using TDZ in a suitable level for in vitro multiplication stage followed by using 2.0 g L-1 of activated charcoal to obtain well rooted shoots is efficient for ipê-roxo micropropagation in a low cost-manner and quickly, besides providing knowledge about how to keep this threatened extinction species in an in vitro environment, which may help other conservation studies.Este estudo objetivou avaliar a influência das citocininas durante o estágio de multiplicação in vitro e a combinação entre carvão ativado com o ácido indol-3-butírico (AIB) durante o enraizamento in vitro de Handroanthus impetiginosus. Para a multiplicação in vitro, os segmentos nodais dos brotos obtidos a partir do estabelecimento de plântulas in vitro foram inoculados em meio de cultura Woody Plant Medium (WPM), com e sem as seguintes concentrações de 6-benzilaminopurina (BAP), cinetina (KIN) e tidiazuron (TDZ): 0,5; 1,0; 2,0; 4,0 e 8,0 µmol L-1. Para o enraizamento in vitro, brotos foram inoculados em meio WPM contendo combinações entre AIB (1,0; 3,0; 6,0 e 9,0 μmol L-1) e carvão ativado (1,0; 2,0 e 3,0 g L‑1), bem como suas ausências no meio de cultura. O maior número de brotos e gemas foi alcançado após usar 8,0 μmol L-1 de TDZ, enquanto que o melhor enraizamento ocorreu após a adição de 2,0 g L-1 de carvão ativado, independente da concentração de AIB. Nossos resultados mostram que usar TDZ em níveis adequados para o estágio de multiplicação in vitro seguido pelo uso de 2,0 g L-1 de carvão ativado para obter brotos bem enraizados é eficiente para a micropropagação de ipê-roxo de maneira rápida e com baixo custo, além de fornecer conhecimento sobre como manter esta espécie ameaçada de extinção em um ambiente in vitro podendo ajudar outros estudos de conservação

Behavior of lateral buds of Hancornia speciosa after cryopreservation by encapsulation-vitrification

 Hancornia speciosa is a fruitful species from Cerrado biome with high economic potential. However, the intense and disordered extractivism have caused a reduction of its population in its endemic area. In addition, seed recalcitrance negatively affects the conventional conservation of the species. Aiming to find alternatives that enable the long-term conservation of this species, the study’s objective was to assess the behavior of lateral bud’s regrowth after cryopreservation procedures by encapsulation-vitrification technique. Sodium alginate capsules containing lateral buds were pre-cultured in liquid WPM supplemented with 1.0 M glycerol, and subsequently exposed to different concentrations of sucrose (0.3; 0.75 and 1.0 M) for 24 or 48 hours. The capsules were subjected to dehydration in silica gel or airflow hood for 0, 1, 2 and 3 hours before different incubation times in PVS2 (0, 15, 30, 60 and 120 minutes) at 0°C. A high regeneration percentage of lateral buds was observed after cryopreservation of capsules treated with 0.75 M sucrose plus 1.0 M glycerol (24 hours), associated with dehydration in an airflow hood (1 hour) and immersion in PVS2 (15 minutes). Encapsulation-vitrification allowed the long-term conservation, and provided high plant material survival rates after cryopreservation of Hancornia speciosa sensitive explants.