The large-X effect in plants: increased species divergence and reduced gene flow on the Silene X-chromosome
The large-X effect in plants: increased species divergence and reduced gene flow on the Silene X-chromosome
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DOI：
10.1111/mec.13427
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发表时间：
2016-06-01
影响因子：
4.9
通讯作者：
Filatov, Dmitry A.
中科院分区：
文献类型：
--
作者：
Hu, Xin-Sheng;Filatov, Dmitry A.
在许多动物中，X染色体不成比例地大量参与了近缘物种的分离（大X效应），其中X连锁基因在异配子性别中大多是半合子的。有害的隐性突变的表达被认为是驱动杂交不育中X染色体的频繁参与，以及减少X连锁基因的种间基因流动。在这里，我们评估了X染色体在两种密切相关的植物物种--白色和红色Campions（宽叶蝇子草和宽叶蝇子草）的物种形成中的作用。dioica）--在欧洲广泛杂交。这两个物种进化独立的性别和性染色体相对较近（类似于10（7）年），与大多数动物物种不同，大多数X-连锁基因具有完整的Y-连锁同源物。我们表明，X-连锁基因显示出一个非常小的和微不足道的量的种间基因流，而涉及常染色体位点的基因流是显着的，足以使两个物种的基因库均质化。这些研究结果是一致的假设的大X效应在Silene，并包括这种效果在植物中的第一份报告。非半合子的许多X-连锁基因在蝇子草男性表明，隐性突变的选择可能不是必不可少的大X效应的发生。讨论了Silene大X效应的几种可能原因。
The disproportionately large involvement of the X-chromosome in the isolation of closely related species (the large-X effect) has been reported for many animals, where Xlinked genes are mostly hemizygous in the heterogametic sex. The expression of deleterious recessive mutations is thought to drive the frequent involvement of the X-chromosome in hybrid sterility, as well as to reduce interspecific gene flow for X-linked genes. Here, we evaluate the role of the X-chromosome in the speciation of two closely related plant species -the white and red campions (Silene latifolia and S. dioica) - that hybridize widely across Europe. The two species evolved separate sexes and sex chromosomes relatively recently (similar to 10(7) years), and unlike most animal species, most X-linked genes have intact Y-linked homologs. We demonstrate that the X-linked genes show a very small and insignificant amount of interspecific gene flow, while gene flow involving autosomal loci is significant and sufficient to homogenize the gene pools of the two species. These findings are consistent with the hypothesis of the large-X effect in Silene and comprise the first report of this effect in plants. Non-hemizygosity of many X-linked genes in Silene males indicates that exposure of recessive mutations to selection may not be essential for the occurrence of the large-X effect. Several possible causes of the large-X effect in Silene are discussed.