No abstract

The Amazonian bamboo forests are located in an important region of high biodiversity in Brazil, Peru and Bolivia, forming the largest native bamboo forest reserve in the world. However, the bamboos from these forests have characteristics that hinder their propagation. This study aimed to evaluate the biocide action of a plant preservative mixture for controling contaminants, during the in vitro establishment of Guadua latifolia (Bonpl.) Kunth, a species native to the region. Nodal segments were cultured in a semi-solid medium containing Plant Preservative Mixture (PPMTM), at the concentrations of 0; 1; 2; and 3 mL L-1, and supplemented with 2 mg L-1 of 6-benzylaminopurine. The analyzed variables were number of shoots, percentage of bacterial and fungal contamination, and shoot survival. The treatments with the synthetic biocide were efficient in controlling the in vitro contamination caused by bacteria and fungi (Fusarium sp.), also presenting the highest survival rate of regenerated shoots. For the in vitro establishment of this native bamboo species, the use of 2 mL L-1 of PPMTM is recommended.

The main factors governing Hevea brasiliensis germination and seedling establishment remains unclear. We examined the effect of growth regulators Indole 3-Acetic Acid (IAA) and 6-Benzylaminopurine (BAP), and their interactions on germination and the development of mature zygotic embryos (MZE) and protein profi le of Hevea brasiliensis seedlings from wild and cultivated (clone PB 250) genotypes. Embryonic axes excised from seeds (wild and clone PB 250) were inoculated in Murashige and Skoog medium (control) and supplemented with IAA (3 µM) and BAP (6 µM) individually and their combination (3 µM IAA + 6 µM BAP). For both genotypes, the mature embryos displayed a high percentage of germination and establishment, and the seedlings were characterized by protein bands ranging from 7 to 30 kDa. Notably, the wild genotype showed proteins in the 14 kDa range, which may be associated with one of the major rubber elongation factors (REF). The wild and clone genotypes presented different behavior and strategies in relation to the protein profi le in the presence of different growth regulators. Although the latex biosynthetic pathway and its mechanisms of regulation still remain largely unknown, our results aid in our understanding of the dynamics of proteins in different rubber tree clones in vitro.

Bamboos from the genus Guadua in the Southwestern Amazon basin are difficult to propagate because of their recalcitrant characteristics. This study aimed to evaluate the action of 6-benzylaminopurine (BA) during in vitro multiplication of G. latifolia in a laboratory for clonal seedling production. In vitro multiplication was performed using the cytokinin 6-benzylaminopurine at concentrations of 0, 2, 4, 6, 8 mg L-1 in glass tubes containing liquid medium, incubated for 38 days. The analyzed variables were shoot height, number of shoots, multiplication rate, and the presence of callus and roots in two consecutive subcultures. The use of 6-benzylaminopurine during in vitro multiplication was effective at increasing the number of shoots in the first and second subculture. Shoot height was not influenced by the cytokinin in the culture with a maximum multiplication rate of 4.44 shoots. Therefore, the use of 6 mg L-1 of BA is recommended during in vitro multiplication and to obtain a high multipication rate.

Mesmo considerando os avanços nos estudos de micropropagação em Hevea spp., a compreensão dos estímulos e condições necessárias para o estabelecimento do cultivo in vitro ainda são limitadas. Uma das razões para isto acontecer é devido à falta de um protocolo eficiente para a propagação de clones elites de seringueira em larga escala. Neste sentido, investigamos o efeito do ácido 2,4-diclorofenoxiacético na indução de calos em segmentos foliares de Hevea spp., bem como o uso do PPM® (Plant Preservative Mixture) na inibição de contaminações. Folhas juvenis de seringueira foram inoculadas em meio de cultura MS (Murashig Skoog) suplementado com 2,4-D (0; 0,25; 0,5; 1,0; 2,0 e 4,0 mg L-1) com biocida PPM® (0 e 1,0 mL L-1). Após 60 dias foi possível observar maior porcentagem de sobrevivência e expressiva oxidação fenólica na presença do PPM®. As concentrações de 2,4-D (2,0 e 4,0 mg L-1) combinadas com PPM® (1 mL L-1) foram eficientes na inibição de contaminações microbianas. A indução de calo ocorreu no tratamento contendo 1 mg L-1 de 2,4-D e 1 mL L-1 de PPM® e formou um calo compacto com coloração branca. O protocolo utilizado neste trabalho foi eficiente para desinfestação dos explantes foliares de Hevea spp.