Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel.
Theor Appl Genet. 2012 May;124(7):1365-73. doi: 10.1007/s00122-012-1793-y.
Transposable elements (TEs) account for up to 80% of the wheat genome and are considered one of the main drivers of wheat genome evolution. However, the contribution of TEs to the divergence and evolution of wheat genomes is not fully understood. In this study, we have developed 55 miniature inverted-repeat transposable element (MITE) markers that are based on the presence/absence of an element, with over 60% of these 55 MITE insertions associated with wheat genes. We then applied these markers to assess genetic diversity among Triticum and Aegilops species, including diploid (AA, BB and DD genomes), tetraploid (BBAA genome) and hexaploid (BBAADD genome) species. While 18.2% of the MITE markers showed similar insertions in all species indicating that those are fossil insertions, 81.8% of the markers showed polymorphic insertions among species, subspecies, and accessions. Furthermore, a phylogenetic analysis based on MITE markers revealed that species were clustered based on genus, genome composition, and ploidy level, while 47.13% genetic divergence was observed between the two main clusters, diploids versus polyploids. In addition, we provide evidence for MITE dynamics in wild emmer populations. The use of MITEs as evolutionary markers might shed more light on the origin of the B-genome of polyploid wheat.
转座元件（TEs）占小麦基因组的 80%，被认为是小麦基因组进化的主要驱动力之一。然而，TEs 对小麦基因组分化和进化的贡献还不完全清楚。在这项研究中，我们开发了 55 个基于元件存在/缺失的微型反向重复转座元件（MITE）标记，其中超过 60%的这些 55 个 MITE 插入与小麦基因相关。然后，我们应用这些标记来评估包括二倍体（AA、BB 和 DD 基因组）、四倍体（BBAA 基因组）和六倍体（BBAADD 基因组）物种在内的小麦属和山羊草属物种之间的遗传多样性。虽然 18.2%的 MITE 标记在所有物种中显示出相似的插入，表明这些是化石插入，但 81.8%的标记在物种、亚种和品系之间显示出多态性插入。此外，基于 MITE 标记的系统发育分析表明，物种根据属、基因组组成和倍性水平聚类，而在两个主要聚类（二倍体与多倍体）之间观察到 47.13%的遗传分化。此外，我们还提供了野生二粒小麦群体中 MITE 动态的证据。MITE 作为进化标记的使用可能会更深入地了解多倍体小麦 B 基因组的起源。
