Rodionov A V, Tiupa N B, Kim E S, Machs E M, Loskutov I G
Genetika. 2005 May;41(5):646-56.
To examine the genomic structure of Avena macrostachya, internal transcribed spacers, ITS1 and ITS2, as well as nuclear 5.8S tRNA genes from three oat species with AsAs karyotype (A. wiestii, A. hirtula, and A. atlantica), and those from A. longiglumis (AlAl), A. canariensis (AcAc), A. ventricosa (CvCv), A. pilosa, and A. clauda (CpCp) were sequenced. All species of the genus Avena examined represented a monophyletic group (bootstrap index = 98), within which two branches, i.e., species with A- and C-genomes, were distinguished (bootstrap indices = 100). The subject of our study, A. macrostachya, albeit belonging to the phylogenetic branch of C-genome oat species (karyotype with submetacentic and subacrocentric chromosomes), has preserved an isobrachyal karyotype, (i.e., that containing metacentric chromosomes), probably typical of the common Avena ancestor. It was suggested to classify the A. macrostachya genome as a specific form of C-genome, Cm-genome. Among the species from other genera studied, Arrhenatherum elatius was found to be the closest to Avena in ITS1 and ITS structure. Phylogenetic relationships between Avena and Helictotrichon remain intriguingly uncertain. The HPR389153 sequence from H. pratense genome was closest to the ITS1 sequences specific to the Avena A-genomes (p-distance = 0.0237), while the differences of this sequence from the ITS1 of A. macrostachya reached 0.1221. On the other hand, HAD389117 from H. adsurgens was close to the ITS1 specific to Avena C-genomes (p-distance = 0.0189), while its differences from the A-genome specific ITS1 sequences reached 0.1221. It seems likely that the appearance of highly polyploid (2n = 12-21x) species of H. pratense and H. adsurgens could be associated with interspecific hybridization involving Mediterranean oat species carrying A- and C-genomes. A hypothesis on the pathways of Avena chromosomes evolution during the early stages the oat species divergence is proposed.
为研究大穗燕麦（Avena macrostachya）的基因组结构，对三种具有AsAs核型的燕麦物种（威氏燕麦（A. wiestii）、硬毛燕麦（A. hirtula）和大西洋燕麦（A. atlantica））以及长颖燕麦（A. longiglumis，AlAl）、加那利燕麦（A. canariensis，AcAc）、膨果燕麦（A. ventricosa，CvCv）、毛燕麦（A. pilosa）和克劳德燕麦（A. clauda，CpCp）的内部转录间隔区ITS1和ITS2以及核5.8S tRNA基因进行了测序。所研究的燕麦属所有物种代表一个单系类群（自展指数 = 98），在该类群中区分出两个分支，即具有A基因组和C基因组的物种（自展指数 = 100）。我们的研究对象大穗燕麦，尽管属于C基因组燕麦物种的系统发育分支（具有亚中着丝粒和亚端着丝粒染色体的核型），但保留了等臂染色体核型（即含有中着丝粒染色体），这可能是普通燕麦祖先的典型特征。有人建议将大穗燕麦基因组归类为C基因组的一种特殊形式，即Cm基因组。在所研究的其他属的物种中，发现草原看麦娘（Arrhenatherum elatius）在ITS1和ITS结构上与燕麦最接近。燕麦与异燕麦（Helictotrichon）之间的系统发育关系仍然令人好奇地不确定。来自草地异燕麦（H. pratense）基因组的HPR389153序列与燕麦A基因组特有的ITS1序列最接近（p距离 = 0.0237），而该序列与大穗燕麦ITS1的差异达到0.1221。另一方面，来自上升异燕麦（H. adsurgens）的HAD389117与燕麦C基因组特有的ITS1接近（p距离 = 0.0189），而其与A基因组特有的ITS1序列的差异达到0.1221。似乎草地异燕麦和上升异燕麦的高多倍体（2n = 12 - 21x）物种的出现可能与涉及携带A和C基因组的地中海燕麦物种的种间杂交有关。提出了一个关于燕麦物种分化早期阶段燕麦染色体进化途径的假说。
