Department of Field Crops, Faculty of Agriculture, University of Cukurova, 01330 Adana, Turkey.
Genome. 2009 Nov;52(11):926-34. doi: 10.1139/g09-067.
Recent studies in the genera Aegilops and Triticum showed that allopolyploid formation triggers rapid genetic and epigenetic changes that lead to cytological and genetic diploidization. To better understand the consequences of cytological diploidization, chromosome pairing and seed fertility were studied in S1, S2, and S3 generations of 18 newly formed allopolyploids at different ploidy levels. Results showed that bivalent pairing at first meiotic metaphase was enhanced and seed fertility was improved during each successive generation. A positive linear relationship was found between increased bivalent pairing, improved fertility, and elimination of low-copy noncoding DNA sequences. These findings support the conclusion that rapid elimination of low-copy noncoding DNA sequences from one genome of a newly formed allopolyploid, different sequences from different genomes, is an efficient way to quickly augment the divergence between homoeologous chromosomes and thus bring about cytological diploidization. This facilitates the rapid establishment of the raw allopolyploids as successful, competitive species in nature.
最近对小麦属和山羊草属的研究表明，异源多倍体的形成引发了快速的遗传和表观遗传变化，导致细胞学和遗传上的二倍体化。为了更好地理解细胞学二倍体化的后果，研究人员在不同倍性水平的 18 个新形成的异源多倍体的 S1、S2 和 S3 代中研究了染色体配对和种子育性。结果表明，第一次减数分裂中期的二价体配对增强，并且在每个连续的世代中种子育性提高。发现增加的二价体配对、提高的育性与低拷贝非编码 DNA 序列的消除之间存在正线性关系。这些发现支持这样的结论，即从新形成的异源多倍体的一个基因组中快速消除低拷贝非编码 DNA 序列，不同基因组的不同序列，是快速增加同源染色体之间的差异并实现细胞学二倍体化的有效途径。这有助于原始异源多倍体迅速成为自然界中成功的、有竞争力的物种。
