De Novo Centromere Formation and Centromeric Sequence Expansion in Wheat and its Wide Hybrids.
De Novo Centromere Formation and Centromeric Sequence Expansion in Wheat and its Wide Hybrids.
复制标题
小麦及其杂种的从头着丝粒形成和着丝粒序列扩展
DOI：
10.1371/journal.pgen.1005997
复制
发表时间：
2016-04
期刊：
影响因子：
4.5
通讯作者：
Han F
中科院分区：
文献类型：
--
作者：
Guo X;Su H;Shi Q;Fu S;Wang J;Zhang X;Hu Z;Han F
着丝粒通常含有串联重复序列，但着丝粒功能不一定依赖于这些序列。我们鉴定了小麦非整倍体（Triticum aestivum）和小麦远缘杂种后代中具有显著数量变化的小麦着丝粒反转录转座子（CRW）的功能着丝粒。在一些小麦双端体系和远缘杂种的附加系中，CRW信号强烈减弱或基本消失。CRW序列的全部丢失，但在这些品系中存在CENH 3，表明着丝粒是从头形成的。在携带大的复杂基因组或没有测序基因组的小麦及其广泛的杂交种中，我们单独或与CENH 3-ChIP-seq组合进行CENH 3-ChIP-dot-blot方法，并鉴定了存在于新着丝粒处的异位基因组序列。此外，在新的着丝粒上，所鉴定的DNA序列的转录显著增加，表明相应序列的转录可能与新的着丝粒形成有关。在小麦-Th中观察到了由着丝粒断裂诱导的含有两个和三个CRW序列的稳定的外源染色体。elongatum杂交衍生物，但只有一个是一个功能性的着丝粒。在小麦-黑麦（Secale cereale）杂种中，黑麦着丝粒特异序列沿染色体臂沿着伸展，可能引起了着丝粒的扩展。在小麦远缘杂交中，染色体重排引起的着丝粒序列的频繁和显著的数量改变已被系统地描述，这可能影响杂种中外源染色体的保留或丢失。因此，远缘杂交中的着丝粒行为可能对生物多样性的产生产生重要影响，最终对物种形成产生影响。
Centromeres typically contain tandem repeat sequences, but centromere function does not necessarily depend on these sequences. We identified functional centromeres with significant quantitative changes in the centromeric retrotransposons of wheat (CRW) contents in wheat aneuploids (Triticum aestivum) and the offspring of wheat wide hybrids. The CRW signals were strongly reduced or essentially lost in some wheat ditelosomic lines and in the addition lines from the wide hybrids. The total loss of the CRW sequences but the presence of CENH3 in these lines suggests that the centromeres were formed de novo. In wheat and its wide hybrids, which carry large complex genomes or no sequenced genome, we performed CENH3-ChIP-dot-blot methods alone or in combination with CENH3-ChIP-seq and identified the ectopic genomic sequences present at the new centromeres. In adcdition, the transcription of the identified DNA sequences was remarkably increased at the new centromere, suggesting that the transcription of the corresponding sequences may be associated with de novo centromere formation. Stable alien chromosomes with two and three regions containing CRW sequences induced by centromere breakage were observed in the wheat-Th. elongatum hybrid derivatives, but only one was a functional centromere. In wheat-rye (Secale cereale) hybrids, the rye centromere-specific sequences spread along the chromosome arms and may have caused centromere expansion. Frequent and significant quantitative alterations in the centromere sequence via chromosomal rearrangement have been systematically described in wheat wide hybridizations, which may affect the retention or loss of the alien chromosomes in the hybrids. Thus, the centromere behavior in wide crosses likely has an important impact on the generation of biodiversity, which ultimately has implications for speciation.