No abstract

O sisal (Agave sisalana Perrine) é utilizado para a extração das fibras contidas em suas folhas, sendo a principal fibra dura produzida no mundo. Entretanto, tem sido observado um declínio dessa cultura, devido a uma doença causada pelo fungo de solo Aspergilus niger. A biotecnologia, em especial as técnicas de cultura de tecidos, representa uma alternativa viável para a propagação dessa espécie. Dentre essas técnicas, está a embriogênese somática e, nesse sentido, este estudo objetivou caracterizar a morfogênese in vitro, durante a embriogênese somática, em A. sisalana Perrine. Em todos os experimentos, utilizaram-se bulbilhos como explantes e meio de cultura MS½ acrescido de sacarose (30,0 g L-1), solidificado com ágar (7,0 g L-1) suplementado com diferentes concentrações de auxinas e citocininas. Os explantes formaram calos com aspectos compactos e semicompactos, evidenciando células embriogênicas que se converteram em embriões somáticos, com o uso de 2,4-D e BAP. Por meio das análises anatômicas, pôde-se observar embriões em estádios globular e torpedo e a não conexão com o calo mãe.

O objetivo deste trabalho foi identificar cultivares geneticamente divergentes de mamoneira (Ricinus communis) com uso de marcadores RAPD. Um total de 58 iniciadores RAPD foi usado na genotipagem de 15 cultivares. A dissimilaridade genética entre as cultivares foi calculada a partir do índice de Jaccard, tendo-se utilizado o método da média aritmética não ponderada (UPGMA). Foram identificados 552 fragmentos, sendo 311 polimórficos (56,3%). As cultivares foram agrupadas em cinco grupos, evidência de que há divergência genética entre elas. Os marcadores moleculares do tipo RAPD são eficientes no estudo da dissimilaridade em mamoneira.

The objective of this work was to estimate the genetic parameters and genetic divergence of two species of Physalis based on fruit traits, as well as the correlations between these traits. The experiment was carried out in a randomized complete block, with three treatments (P. philadelphica and the green and purple varieties of P. ixocarpa), and six replicates. The following traits were evaluated: average fruit mass (AFM), soluble solids (SS), longitudinal fruit diameter (LFD), transversal fruit diameter (TFD), total fruit mass (TFM), number of fruit per plant (NF), reducing sugars (RS), and total sugars (TS). Genetic divergence was estimated by Tocher’s and the UPGMA methods. There was genetic divergence between the Physalis species, with a higher contribution of AFM, LFD, and TFD, mainly by Tocher’s method. A positive correlation was observed between AFM x LFD, AFM x TFD, and LFD x TFD, and a negative correlations between LFD x TFM, TFD x TFM, and NF x RS. The species were discriminated by total sugars. The AFM, LFD, TFD, and TS traits show significant genetic variation and high values of heritability; therefore, they are suitable targets for the genetic breeding of the evaluated Physalis species.

The present study aims to describe the behavior of the chromosomes in the microsporogenesis and to estimate the pollen viability in Physalis ixocarpa, for purposes of genetic improvement of the species. Floral buds previously collected and fixed in Carnoy (3 : 1) were analyzed under a microscope after being stained with acetic carmine (1%). The number of cells present in each phase of meiosis I and II were determined: prophase, metaphase, anaphase, telophase and the formation of tetrads. The irregularities observed in each of the analyzed phases were recorded. The Meiotic Index (MI) was calculated. The viability of the pollen was determined according to the level of staining: pollen stained red as viable and yellowish-green or colorless as non-viable. The percentage of viable pollen grains was determined by the number of pollen grains stained by the total number of evaluated pollen 100. A total of 2256 meiocytes were observed. Of these, 788 meiocytes were measured in meiosis I, 762 cells were observed in meiosis II and 706 tetrads. The calculated MI for P. ixocarpa was 100%, indicating that the species are meiotically stable. The estimated pollen viability for the evaluation of 3600 pollen grains was 93.11% and considered highly viable. In the present study, the presence of pollenkitt adhered to the pollen grains was observed. Thus, the microsporogenesis process is normal, resulting in the formation of highly viable pollen grains.