Cytogenetics and cytotaxonomy of Velloziaceae.
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Chromosome number and other cytological features are reported from 35 species of Velloziaceae, including several african and brazilian populations. All analyzed species show areticulate interphase nuclei and prophase/prometaphase chromosomes with proximal early condensation. Most heteropycnotic blocks do not seem to correspond to heterochromatin since, at least in Vellozia patens, they do not stain differentially after C-banding procedures. Regarding the chromosome number, three main groups could be identified. The first comprised diploid species of the genera Nanuza, Vellozia and the brazilian species of Xerophyta with 2n=14 or 16; the second comprised tetraploid species with 2n=34, and included all brazilian species of subfam. Barbacenioideae; the third group, of hexaploid species, comprised the African representatives of the genus Xerophyta. A single population of Vellozia, possibly of hybrid origin, had 2n~=32. A basic number of x=8 is proposed for the family. The karyological information supports the hypothesis that the Velloziaceae originated on the South American, rather than on the African continent.
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Cytotaxonomy, Heterochromation, Citotaxonomia, Cromossoma, Velloziaceae, chromosomes