Born in the mitochondrion and raised in the nucleus: evolution of a novel tandem repeat family in Medicago polymorpha (Fabaceae)
Born in the mitochondrion and raised in the nucleus: evolution of a novel tandem repeat family in Medicago polymorpha (Fabaceae)
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DOI：
10.1111/tpj.15676
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发表时间：
2022-02-14
期刊：
影响因子：
7.2
通讯作者：
Jansen, Robert K.
中科院分区：
文献类型：
--
作者：
Choi, In-Su;Wojciechowski, Martin F.;Jansen, Robert K.
植物核基因组中含有通过细胞内基因转移(IGT)从细胞器(线粒体和叶绿体)获得的序列元件。核基因组还显示了大量的重复内容，这表明任何序列都可以很容易地被扩增。植物核基因组的这两个方面得到了很好的认识，但很少联系在一起。通过对31个紫花苜蓿分类群的调查，我们在多态紫花苜蓿及其近缘种的核基因组中发现了IGT后含有rps10的线粒体(Mt)DNA序列的异常高扩增。扩增的序列是由5个不同的重复基序(2157、1064、987、971和587bp)组成的串联阵列，这些重复基序与多态分枝杆菌核基因组中的mt基因组(有丝分裂组)背道而驰。在核染色体的7个位点(6个基因间区和1个端粒)上发现了类似mt rps 10的排列，是最丰富的串联重复序列家族，占总基因组DNA的1.6-3.0%，大约是多态分枝杆菌整个有丝分裂体值的3倍。与典型的mt基因相比，mtrps10类似序列的覆盖率在多态和近缘物种中高出691.5-7198倍。除了IGT后扩增，我们的分析还确定了规范的端粒重复序列和物种特定的卫星阵列，这可能归因于多态分枝杆菌的祖先染色体融合。讨论了染色体不稳定性与多态支原体mt rps 10类串联重复序列家族之间的可能关系。
Plant nuclear genomes harbor sequence elements derived from the organelles (mitochondrion and plastid) through intracellular gene transfer (IGT). Nuclear genomes also show a dramatic range of repeat content, suggesting that any sequence can be readily amplified. These two aspects of plant nuclear genomes are well recognized but have rarely been linked. Through investigation of 31 Medicago taxa we detected exceptionally high post-IGT amplification of mitochondrial (mt) DNA sequences containing rps10 in the nuclear genome of Medicago polymorpha and closely related species. The amplified sequences were characterized as tandem arrays of five distinct repeat motifs (2157, 1064, 987, 971, and 587 bp) that have diverged from the mt genome (mitogenome) in the M. polymorpha nuclear genome. The mt rps10-like arrays were identified in seven loci (six intergenic and one telomeric) of the nuclear chromosome assemblies and were the most abundant tandem repeat family, representing 1.6-3.0% of total genomic DNA, a value approximately three-fold greater than the entire mitogenome in M. polymorpha. Compared to a typical mt gene, the mt rps10-like sequence coverage level was 691.5-7198-fold higher in M. polymorpha and closely related species. In addition to the post-IGT amplification, our analysis identified the canonical telomeric repeat and the species-specific satellite arrays that are likely attributable to an ancestral chromosomal fusion in M. polymorpha. A possible relationship between chromosomal instability and the mt rps10-like tandem repeat family in the M. polymorpha clade is discussed.