驴蹄草性染色体中重复元件组成存在根本差异。
Fundamentally different repetitive element composition of sex chromosomes in Rumex acetosa.
机构信息
Department of Plant Developmental Genetics, The Czech Academy of Sciences, Institute of Biophysics, Královopolská, Brno, Czech Republic.
Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice, Brno, Czech Republic.
出版信息
Ann Bot. 2021 Jan 1;127(1):33-47. doi: 10.1093/aob/mcaa160.
BACKGROUND AND AIMS
Dioecious species with well-established sex chromosomes are rare in the plant kingdom. Most sex chromosomes increase in size but no comprehensive analysis of the kind of sequences that drive this expansion has been presented. Here we analyse sex chromosome structure in common sorrel (Rumex acetosa), a dioecious plant with XY1Y2 sex determination, and we provide the first chromosome-specific repeatome analysis for a plant species possessing sex chromosomes.
METHODS
We flow-sorted and separately sequenced sex chromosomes and autosomes in R. acetosa using the two-dimensional fluorescence in situ hybridization in suspension (FISHIS) method and Illumina sequencing. We identified and quantified individual repeats using RepeatExplorer, Tandem Repeat Finder and the Tandem Repeats Analysis Program. We employed fluorescence in situ hybridization (FISH) to analyse the chromosomal localization of satellites and transposons.
KEY RESULTS
We identified a number of novel satellites, which have, in a fashion similar to previously known satellites, significantly expanded on the Y chromosome but not as much on the X or on autosomes. Additionally, the size increase of Y chromosomes is caused by non-long terminal repeat (LTR) and LTR retrotransposons, while only the latter contribute to the enlargement of the X chromosome. However, the X chromosome is populated by different LTR retrotransposon lineages than those on Y chromosomes.
CONCLUSIONS
The X and Y chromosomes have significantly diverged in terms of repeat composition. The lack of recombination probably contributed to the expansion of diverse satellites and microsatellites and faster fixation of newly inserted transposable elements (TEs) on the Y chromosomes. In addition, the X and Y chromosomes, despite similar total counts of TEs, differ significantly in the representation of individual TE lineages, which indicates that transposons proliferate preferentially in either the paternal or the maternal lineage.
背景和目的
具有明确性染色体的雌雄异株物种在植物界中较为罕见。大多数性染色体会增大，但尚未对导致这种扩张的序列进行全面分析。在这里，我们分析了雌雄异株植物酸模（Rumex acetosa）的性染色体结构，该植物具有 XY1Y2 性别决定机制，并且这是首次对具有性染色体的植物物种进行染色体特异性重复组分析。
方法
我们使用二维荧光原位杂交悬浮（FISHIS）方法和 Illumina 测序，对 R. acetosa 的性染色体和常染色体进行了流式分选和单独测序。我们使用 RepeatExplorer、Tandem Repeat Finder 和 Tandem Repeats Analysis Program 来识别和量化个体重复序列。我们使用荧光原位杂交（FISH）分析了卫星和转座子在染色体上的定位。
主要结果
我们鉴定出了一些新的卫星，它们与先前已知的卫星类似，在 Y 染色体上显著扩张，但在 X 染色体或常染色体上扩张程度较小。此外，Y 染色体的大小增加是由非长末端重复（LTR）和 LTR 反转录转座子引起的，而只有后者导致 X 染色体的增大。然而，X 染色体上的 LTR 反转录转座子谱系与 Y 染色体上的不同。
结论
X 和 Y 染色体在重复组成上有明显的分歧。缺乏重组可能导致各种卫星和微卫星的扩张以及新插入的转座元件（TEs）在 Y 染色体上更快地固定。此外，尽管 X 和 Y 染色体上的 TE 总数相似，但它们在个别 TE 谱系的代表上存在显著差异，这表明转座子在父系或母系中优先增殖。
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