Karyotype analysis in two species of Solanum (Solanaceae) sect. Cyphomandropsis based on chromosome banding

Abstract

To contribute to the cytogenetic characterisation of the Cyphomandra clade of Solanum, fluorescence banding and silver staining were performed on Solanum fusiforme and Solanum stuckertii for the first time. Both species had 2n=24 chromosomes. Solanum fusiforme had a karyotype consisting of 9m+3sm chromosome pairs; one pair had active nucleolar organiser regions (NORs). Solanum stuckertii had 8m+4sm chromosome pairs with two pairs having active NORs.The two species exhibit similar amounts (11%) of constitutive CMA+/DAPI- heterochromatin, rich in GC base pairs. This heterochromatin was distributed in a complex pattern of mainly intercalary bands. Localisation of chromosome-specific markers was successful, allowing recognition of all chromosomes of the complements.With the aim of contributing to a better understanding of the interspecific relationships within the Cyphomandra clade, we discuss our results in conjunction with previous findings for species in this clade.