Comparative cytogenetic analysis of Cestrum (Solanaceae) reveals different trends in heterochromatin and rDNA sites distribution

Species of Cestrum L. (Solanaceae) exhibit large variability in the accumulation of repetitive DNA, although their species possess a stable diploid number with 2n = 16. In this study, we used chromosome banding and fluorescence in situ hybridization (FISH) to characterize the karyotypes and populations of two species, Cestrum nocturnum L. and C. mariquitense Kunth. We also performed a karyotype comparison using 16 idiograms, of which 4 were developed in this study and 12 were obtained from the literature. Cestrum nocturnum displayed more bands than C. mariquitense, but the latter exhibited greater interpopulational variation in the band patterns. There was a tendency for large bands to be located at intercalary/terminal regions and for small bands to be located at intermediate/proximal regions. The idiogram comparison revealed a large variation in the amount, distribution, and size of heterochromatic bands. FISH with rDNA probes revealed stability in the number and location of 5S sites, while 45S was more...