Longitudinal differentiation in chromosomes of some Sesbania Scop. species(Fabaceae)

Three different techniques were applied to analyze the patterns of longitud inal chromosome differentiation in five Sesbania species (S. exasperata, S. punicea, S. sesban, S. tetraptera, and two different geographical populati ons of S. virgata). For all the species investigated, the prophase chromoso me condensation was always proximal. After staining with the fluorochromes chromomycin A(3) and DAPI, each karyotype revealed two or four CMA(+)/ DAPI (-) heterochromatic blocks, apparently corresponding to the nucleolus organ izing regions. However, in S. virgata two or four CMA(+) bands were observe d, depending on the population studied. No DAPI(+) bands were observed. C-b anding showed the most diversified patterns, being a more useful technique to distinguish karyorypes of Sesbania species. The largest amount of hetero chromatin was observed in S. virgata (subgenus Daubentonia) whereas the sma llest was found in S. sesban (subgenus Sesbania).