Zuo Hongwei, Wu Panpan, Wu Dexiang, Sun Genlou
College of Agronomy, Anhui Agricultural University, Hefei, Anhui, China.
College of Agronomy, Anhui Agricultural University, Hefei, Anhui, China; Biology Department, Saint Mary's University, Halifax, Nova Scotia, Canada.
PLoS One. 2015 May 6;10(5):e0125417. doi: 10.1371/journal.pone.0125417. eCollection 2015.
To study origin and evolutionary dynamics of tetraploid Elymus trachycaulus that has been cytologically defined as containing StH genomes, thirteen accessions of E. trachycaulus were analyzed using two low-copy nuclear gene Pepc (phosphoenolpyruvate carboxylase) and Rpb2 (the second largest subunit of RNA polymerase II), and one chloroplast region trnL-trnF (spacer between the tRNA Leu (UAA) gene and the tRNA-Phe (GAA) gene). Our chloroplast data indicated that Pseudoroegneria (St genome) was the maternal donor of E. trachycaulus. Rpb2 data indicated that the St genome in E. trachycaulus was originated from either P. strigosa, P. stipifolia, P. spicata or P. geniculate. The Hordeum (H genome)-like sequences of E. trachycaulus are polyphyletic in the Pepc tree, suggesting that the H genome in E. trachycaulus was contributed by multiple sources, whether due to multiple origins or introgression resulting from subsequent hybridization. Failure to recovering St copy of Pepc sequence in most accessions of E. trachycaulus might be caused by genome convergent evolution in allopolyploids. Multiple copies of H-like Pepc sequence from each accession with relative large deletions and insertions might be caused by either instability of Pepc sequence in H- genome or incomplete concerted evolution. Our results highlighted complex evolutionary history of E. trachycaulus.
为了研究细胞学上已定义为含有StH基因组的四倍体糙毛披碱草（Elymus trachycaulus）的起源和进化动态，利用两个低拷贝核基因磷酸烯醇式丙酮酸羧化酶（Pepc）和RNA聚合酶II的第二大亚基（Rpb2）以及一个叶绿体区域trnL-trnF（tRNA亮氨酸（UAA）基因与tRNA-苯丙氨酸（GAA）基因之间的间隔区）对13份糙毛披碱草材料进行了分析。我们的叶绿体数据表明，拟鹅观草属（St基因组）是糙毛披碱草的母本供体。Rpb2数据表明，糙毛披碱草中的St基因组起源于线叶拟鹅观草（P. strigosa）、狭叶拟鹅观草（P. stipifolia）、穗状拟鹅观草（P. spicata）或膝曲拟鹅观草（P. geniculate）。糙毛披碱草中类似大麦（H基因组）的序列在Pepc树中是多系的，这表明糙毛披碱草中的H基因组是由多个来源贡献的，无论是由于多个起源还是后续杂交导致的渐渗。在大多数糙毛披碱草材料中未能恢复Pepc序列的St拷贝可能是由于异源多倍体中的基因组趋同进化所致。每个材料中多个类似H的Pepc序列拷贝具有相对较大的缺失和插入，可能是由于H基因组中Pepc序列的不稳定性或不完全的协同进化所致。我们的结果突出了糙毛披碱草复杂的进化历史。
