Low cytomolecular diversification in the genus Stylosanthes Sw. (Papilionoideae Leguminosae)

摘要

(Papilionoideae, Leguminosae) is a predominantly Neotropical genus with ~48 species that include worldwide important forage species. This study presents the chromosome number and morphology of eight species of the genus ( , and ). In addition, staining with CMA and DAPI, hybridization with 5S and 35S rDNA probes, and estimation of DNA content were performed. The interpretation of chromosome diversification was anchored by a comparison with the sister genus and a dated molecular phylogeny based on nuclear and plastid loci. species showed 2 = 20, with low cytomolecular diversification regarding 5S rDNA, 35S rDNA, and genome size. has a more ancient diversification (~7 Mya in the Pliocene) than the relatively recent (~2 Mya in the Pleistocene), and it seems more diverse than its sister lineage. Our data support the idea that the cytomolecular stability of in relation to could be a result of its recent origin. The recent diversification of could also be related to the low morphological differentiation among species, and to the recurrent formation of allopolyploid complexes.