Showing papers on "Cestrum published in 2006"
TL;DR: The results suggest that karyotype differentiation can occur mainly due to changes in repetitive DNA, with little modification in the general composition of the conventionally stained karyotypes.
Abstract: We studied the karyotypes of four Brazilian Cestrum species (C. amictum, C. intermedium, C. sendtnerianum and C. strigilatum) using conventional Feulgen staining, C-Giemsa and C-CMA3/DAPI banding, induction of cold-sensitive regions (CSRs) and fluorescent in situ hybridization (FISH) with rDNA probes. We found that the karyotypes of all four species was 2n = 2x = 16, with, except for the eighth acrocentric pair, a predominance of meta- and submetacentric chromosomes and various heterochromatin classes. Heterochromatic types previously unreported in Cestrum as neutral C-CMA30/DAPI0 bands, CMA3+ bands not associated with NORs, and C-Giemsa/CSR/DAPI- bands were found. The heterochromatic blocks varied in size, number, position and composition. The 45S rDNA probe preferentially located in the terminal and subterminal regions of some chromosomes, while 5S rDNA appeared close to the centromere of the long arm of pair 8. These results suggest that karyotype differentiation can occur mainly due to changes in repetitive DNA, with little modification in the general composition of the conventionally stained karyotype.
53 citations
TL;DR: Phylogenetic analysis of DNA sequences from chloroplast regions and nuclear ribosomal ITS reject the monophyly of the traditionally recognized sections of Cestrum, including sect.
Abstract: Phylogenetic analysis of DNA sequences from chloroplast regions and nuclear ribosomal ITS was conducted to test the monophyly of Cestrum sect. Habrothamnus and investigate its relationships with other sections of Cestrum. Molecular divergence was very low among the sampled species, suggesting a rapid diversification in Cestrum. Individual and combined analyses of these molecular data sets using maximum parsimony and Bayesian inference reject the monophyly of the traditionally recognized sections of Cestrum, including sect. Habrothamnus. Infrageneric classifications will require significant revision. Nevertheless, the resolved monophyletic clades in this molecular analysis are geographically structured.
14 citations
TL;DR: Karyotype diversification in tribe Cestreae is suggested to have been accompanied by a tendency towards slight asymmetry and increased genome length.
Abstract: The somatic chromosomes of Cestrum bigibbosum Pittier, C. buxifolium Kunth, Sessea corymbosa Goudot ex Taylor and Phillips and Vestia foetida (Ruiz et Pav.) Hoffmanns, were examined by classical staining. The number 2n = 2x = 16 was found for all species. The total genome length ranged from 57.70 to 92.09 μm and the average chromosome length from 7.21 to 11.51 μm. Karyotypes were notably symmetrical. Haploid karyotype formulae were 8 m pairs (C. bigibbosum, V. foetida) or 7 m + 1 sm pairs (S. corymbiflora, C. buxifolium). Except Sessea corymbiflora in which satellites were not visualized, the remaining species showed one satellited pair. The species can be distinguished by a combination of karyotype formula, karyotype length, and the position of satellites in a particular chromosome pair. Karyotype diversification in tribe Cestreae is suggested to have been accompanied by a tendency towards slight asymmetry and increased genome length.
12 citations