Gene Loss from a Plant Sex Chromosome System
Gene Loss from a Plant Sex Chromosome System
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DOI：
10.1016/j.cub.2015.03.015
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发表时间：
2015-05-04
期刊：
影响因子：
9.2
通讯作者：
Charlesworth, Deborah
中科院分区：
文献类型：
--
作者：
Bergero, Roberta;Qiu, Suo;Charlesworth, Deborah
性染色体在许多动物和植物谱系中独立进化。当两条同源性染色体之间的重组被抑制后，未重组的Y染色体(和ZW系统中的W染色体)上的基因经历遗传退化，失去其X-或Z-连锁同源物保留的功能，改变其表达，并丢失[1，2]。适应性变化也可能发生，在非重组的Y染色体上，关闭不适应基因的表达[3]，在X染色体上(或ZW系统中的Z)，可能进化出剂量补偿，以增加低表达或补偿异性性[2，4，5]中较差的蛋白质功能。虽然已经为模式物种[3，6]开发了研究遗传退化的经验方法，但这些变化的开始和动态仍然知之甚少，特别是在从头进化的性染色体中。一些植物的性染色体比哺乳动物、鸟类和果蝇的进化要晚得多[7-9]，这使得它们适合于研究从头进化的性染色体的遗传退化的早期阶段。在植物中，单倍体选择应该反对Y染色体上的基因丢失，但最近对两种植物的性染色体的研究估计，10%-30%的X连锁基因缺乏Y连锁转录本[10-12]。在这里，我们提供了证据，在Silene宽叶植物中，这主要涉及Y连锁基因的丢失，而不是Y连锁等位基因的表达被抑制，或者X染色体上的基因增加。我们的结果还表明，在这种植物中没有发生染色体范围的剂量补偿。
Sex chromosomes have evolved independently in numerous animal and plant lineages. After recombination becomes suppressed between two homologous sex chromosomes, genes on the non-recombining Y chromosomes (and W chromosomes in ZW systems) undergo genetic degeneration, losing functions retained by their X- or Z-linked homologs, changing their expression, and becoming lost [1, 2]. Adaptive changes may also occur, both on the non-recombining Y chromosome, to shut down expression of maladapted genes [3], and on the X chromosome (or the Z in ZW systems), which may evolve dosage compensation to increase low expression or compensate for poor protein function in the heterogametic sex [2, 4, 5]. Although empirical approaches to studying genetic degeneration have been developed for model species [3, 6], the onset and dynamics of these changes are still poorly understood, particularly in de novo evolving sex chromosomes. Sex chromosomes of some plants evolved much more recently than those of mammals, birds, and Drosophila [7-9], making them suitable for studying the early stages of genetic degeneration in de novo evolving sex chromosomes. In plants, haploid selection should oppose gene loss from Y chromosomes, but recent work on sex chromosomes of two plant species has estimated that Y-linked transcripts are lacking for 10%-30% of X-linked genes [10-12]. Here, we provide evidence that, in Silene latifolia, this largely involved losses of Y-linked genes, and not suppressed expression of Y-linked alleles, or gene additions to the X chromosome. Our results also suggest that chromosome-wide dosage compensation does not occur in this plant.