Citotaxonomia molecular do gÃnero Callisia Loefl. (Commelinaceae)
AUTOR(ES)
Fernando Roa Ovalle
DATA DE PUBLICAÇÃO
2007
RESUMO
The genus Callisia displays a remarkable diversity in chromosomal number and morphology within and between its sections. In addition, phylogenetic analyses suggest that it is not monophyletic, and some of its species could be more related to Tripogandra. Aiming to investigate the karyotypic evolution of the genus and understand its relationship with Tripogandra, chromosomal morphology, structure of interphase nuclei, prophase condensation pattern and heterochromatin distribution were analyzed in eight species of three sections of Callisia and three species of Tripogandra. The structure of interphase nuclei and prophasic condensation pattern were analyzed in cells stained with Giemsa. Chromosomal morphology was defined from DAPI stained metaphases, whereas the heterochromatin was localized by C-banding and CMA/DAPI fluorochrome staining. The 5S and 45S rDNA sites were revealed by FISH. The results confirmed that Callisia species have an exceptionally high karyotypic diversity. In Callisia section, the chromosome number, the structure of interphase nuclei and the prophasic condensation pattern were conserved, suggesting that it is a natural group. Nevertheless, in this section and section Leptocallisia, both chromosomal morphology and DAPI and C-band distribution had extensive variation. On the other hand, terminal and intersticial position of 45S rDNA and 5S rDNA, respectively, were well conserved. In Tripogandra genus, there was also variation in heterochromatin distribution and structure of interphase nuclei. The present cytogenetic analysis, using heterochromatin banding patterns and in situ hybridization of rDNA probes, showed that cytological differences are not constrained to chromosomal morphology, but also include changes in distribution and composition of the heterochromatin. Karyotypes of Callisia and Tripogandra are very different, making impossible to establish evolutive relationships. The more probable explanation for this high karyotypic diversification in Callisia is the occurrence of multiple rearrangements and amplification of repetitive DNA sequences, along with independent disploidy events
ASSUNTO(S)
fish callisia heterochromatin fish heterocromatina biologia geral callisia chromosomal evolution evoluÃÃo cromossÃmica
