Franco Ana Luiza, Figueredo Amanda, Pereira Lívia de Moraes, Sousa Saulo Marçal de, Souza Gustavo, Carvalho Marcelo Ayres, Simon Marcelo F, Viccini Lyderson Facio
Universidade Federal de Juiz de Fora, Departamento de Biologia, Laboratório de Genética, Juiz de Fora, MG, Brazil.
Universidade Federal de Pernambuco, Departamento de Botânica, Laboratório de Citogenética e Evolução Vegetal, CCB, Recife, PE, Brazil.
Genet Mol Biol. 2020 Mar 6;43(1):e20180250. doi: 10.1590/1678-4685-GMB-2018-0250. eCollection 2020.
Stylosanthes (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 Stylosanthes (S. acuminata, S. gracilis, S. grandifolia, S. guianensis, S. hippocampoides, S. pilosa, S. macrocephala, and S. ruellioides). In addition, staining with CMA and DAPI, in situ hybridization with 5S and 35S rDNA probes, and estimation of DNA content were performed. The interpretation of Stylosanthes chromosome diversification was anchored by a comparison with the sister genus Arachis and a dated molecular phylogeny based on nuclear and plastid loci. Stylosanthes species showed 2n = 20, with low cytomolecular diversification regarding 5S rDNA, 35S rDNA, and genome size. Arachis has a more ancient diversification (7 Mya in the Pliocene) than the relatively recent Stylosanthes (~2 Mya in the Pleistocene), and it seems more diverse than its sister lineage. Our data support the idea that the cytomolecular stability of Stylosanthes in relation to Arachis could be a result of its recent origin. The recent diversification of Stylosanthes could also be related to the low morphological differentiation among species, and to the recurrent formation of allopolyploid complexes.
笔花豆属（蝶形花亚科，豆科）主要分布于新热带地区，约有48个物种，其中包括在全球范围内具有重要意义的饲料品种。本研究展示了笔花豆属8个物种（尖叶笔花豆、细茎笔花豆、大叶笔花豆、圭亚那笔花豆、海马状笔花豆、柔毛笔花豆、大头笔花豆和吕宋笔花豆）的染色体数目和形态。此外，还进行了CMA和DAPI染色、5S和35S rDNA探针的原位杂交以及DNA含量的估算。通过与近缘属落花生属进行比较，并基于核基因座和质体基因座构建一个带时间信息的分子系统发育树，对笔花豆属的染色体多样化进行了解读。笔花豆属物种的染色体数目为2n = 20，在5S rDNA、35S rDNA和基因组大小方面，细胞分子多样化程度较低。落花生属的多样化历史更为古老（上新世约700万年前），而笔花豆属相对较新（更新世约200万年前），并且落花生属似乎比其近缘谱系更为多样化。我们的数据支持这样一种观点，即笔花豆属相对于落花生属的细胞分子稳定性可能是其近期起源的结果。笔花豆属近期的多样化也可能与物种间较低的形态分化以及异源多倍体复合体的反复形成有关。
