Cytogenetic characterization and chromosome evolution of the striking tropical Andean species of Capsicum (Solanaceae)

Fluorochrome chromosome banding and fluorescent in situ hybridization were used to cytogenetically characterize the striking tropical Andean clade species of Capsicum. An adapted dendrogram of the Capsicum phylogeny is presented, showing taxonomic relationships between karyotypes of the Andean clade species, C. baccatum var. pendulum, C. flexuosum, and the sister group Lycianthes. To date, the Andean clade includes nine species: C. dimorphum, C. geminifolium, C. hookerianum, C. lanceolatum, C. longifolium, C. lycianthoides, C. piuranum, C. regale and C. rhomboideum, all displaying 2n = 26. This group is characterized by conspicuous cytogenetic characters that are very useful in the identification of their species and allow them to be distinguished from the other group of species with x = 13 from the Atlantic forest, and definitely from the clades with x = 12. The species of the Andean clade possess relatively short genomes, with one NOR per haploid complement. The distribution of the heterochromatin is mainly subterminal. A single locus of the 35S and 5S rDNA was found per haploid complement. The discovery of three pairs of 5S rDNA sites in C. regale was surprising. The chromosomal features of these highland clade species could be considered adaptive characters to their geographical distribution.