Cytogenetics and chromosome banding patterns in Caesalpinioideae and Papilionioideae species of Pará, Amazonas, Brazil

Despite the abundance of woody legumes in Brazilian Amazonian rain forests, there are few chromosome counts on the native species of this important region. The present work presents such data for 13 species of Caesalpinioideae (the genera Bauhinia, Caesalpinia, Cassia, Chamaecrista and Senna) and Papilionioideae (Bowdichia, Centrosema and Dioclea) collected from 17 natural populations. Our report represents the first chromosome counts for the genera Bowdichia and Dioclea and for four of the studied species. Observations are made on chromosome morphology, size, condensing behaviour and interphase nucleus structure. Banding with fluorochromes carried out for the first time in Caesalpinioideae revealed discrete CMA+/DAPI– terminal (GC-rich) bands on 2–4 chromosome pairs of most species analysed, with a few species presenting discrete CMA–/DAPI+ (AT-rich) bands. Significant differences in chromosome size, morphology and condensing behaviour were observed among members of the controversial tribe Cassieae (Cassia, Chamaecrista and Senna), revealing the tribe to be a heterogeneous group from the karyological point of view.