Genome size and chromosome number conservation contrasting with karyotype diversity in Hohenbergia (Bromelioideae, Bromeliaceae).

Plant evolution may be triggered by significant chromosome changes. In some plant groups, karyoevolution played an important role, influencing speciation processes. Hohenbergia comprises 48 species distributed through eastern Brazil. Previous cytological information includes few species and only chromosome counts, lacking information about genome size and more accurate karyomorphological investigation. Here, we compare cytomolecular features and genome sizes of 12 Hohenbergia spp. Besides, new measurements of genome sizes of 32 species are reported. All studied species presented 2 n = 50, a number prevalent in Bromelioideae. The genome sizes (2C) varied from 0.74 to 1.52 pg. Despite the apparent homogeneity in chromosome number and genome size in Hohenbergia , significant polymorphism was observed in regard to the distribution of CMA⁺/DAPI⁰ bands and sites of 35S and 5S rDNA in metaphase chromosomes. Seven out of 12 analysed species presented heteromorphic pairs regarding 35S rDNA and/or 5S rDNA. Hohenbergia thus shows karyotypic diversity despite the conservation in chromosome number. [ABSTRACT FROM AUTHOR]