Papadopulos Alexander S T, Chester Michael, Ridout Kate, Filatov Dmitry A
Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.
Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
Proc Natl Acad Sci U S A. 2015 Oct 20;112(42):13021-6. doi: 10.1073/pnas.1508454112. Epub 2015 Oct 5.
The nonrecombining regions of animal Y chromosomes are known to undergo genetic degeneration, but previous work has failed to reveal large-scale gene degeneration on plant Y chromosomes. Here, we uncover rapid and extensive degeneration of Y-linked genes in a plant species, Silene latifolia, that evolved sex chromosomes de novo in the last 10 million years. Previous transcriptome-based studies of this species missed unexpressed, degenerate Y-linked genes. To identify sex-linked genes, regardless of their expression, we sequenced male and female genomes of S. latifolia and integrated the genomic contigs with a high-density genetic map. This revealed that 45% of Y-linked genes are not expressed, and 23% are interrupted by premature stop codons. This contrasts with X-linked genes, in which only 1.3% of genes contained stop codons and 4.3% of genes were not expressed in males. Loss of functional Y-linked genes is partly compensated for by gene-specific up-regulation of X-linked genes. Our results demonstrate that the rate of genetic degeneration of Y-linked genes in S. latifolia is as fast as in animals, and that the evolutionary trajectories of sex chromosomes are similar in the two kingdoms.
已知动物Y染色体的非重组区域会发生基因退化，但此前的研究未能揭示植物Y染色体上存在大规模的基因退化现象。在此，我们发现了一种植物物种——宽叶蝇子草（Silene latifolia）的Y连锁基因发生了快速且广泛的退化，该物种在过去1000万年中从头进化出了性染色体。此前基于转录组对该物种的研究遗漏了未表达的、退化的Y连锁基因。为了鉴定性连锁基因，无论其是否表达，我们对宽叶蝇子草的雄性和雌性基因组进行了测序，并将基因组重叠群与高密度遗传图谱整合。结果显示，45%的Y连锁基因不表达，23%的基因被提前终止密码子打断。这与X连锁基因形成了对比，在X连锁基因中，只有1.3%的基因含有终止密码子，4.3%的基因在雄性中不表达。Y连锁功能基因的丢失部分地通过X连锁基因的基因特异性上调得到了补偿。我们的结果表明，宽叶蝇子草中Y连锁基因的基因退化速度与动物一样快，并且性染色体在这两个王国中的进化轨迹相似。
