2012 Volume 77 Issue 3 Pages 323-332
The F1 hybrids obtained and cytologically investigated from 2 reciprocal cross-combinations in the genus Antirrhinum–A.litigiosum–A.subbaeticum and A. pulverulentum–A. subbaeticum were diploids 2n=2x=16, as their progenitors. In the hybrids pollen mother cells (PMCs) parallel with variously shaped symmetric and asymmetric bivalents with one or more chiasma formation, positioned in different chromosome regions, univalent and multivalent associations, were presented. The lower values of the chiasma frequency and number of ring type of bivalents in F1 plants indicated a certain degree of differentiation between homologous chromosomes of the parent's components and suggested different activities of genes controlling chiasma formation and position. The meiotic irregularities in F1 progeny could be caused from karyotypic dissimilarities between the wild Antirrhinum genomes on the one hand and chromosome rearrangements (presence of multivalent and univalents, late bivalent disjunction, bridge formation) on the other. The evaluation of the chromosome pairing affinities, the abnormalities in chromosome behaviour at anaphase and telophase stages, and the pollen fertility in the F1 hybrids suggested a higher expressed phylogenetic distance between A. litigiosum and A. subbaeticum than the one between A. pulverulentum and A. subbaeticum genome, as the karyotype remoteness between A. litigiosum and A. subbaeticum cytologically seems to be expressed more strongly than that between A. pulverulentum and A. subbaeticum species. The cytological results confirmed the systematic relationships between the studied species in the genus Antirrhinum.A. pulverulentum and A. subbaeticum are closer to each other than to A. litigiosum and are included in the subsection Kickxiella, while A. litigiosum belongs to subsection Antirrhinum.