The Mutation Rate and the Age of the Sex Chromosomes in Silene latifolia
The Mutation Rate and the Age of the Sex Chromosomes in Silene latifolia
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DOI：
10.1016/j.cub.2018.04.069
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发表时间：
2018-06-04
期刊：
影响因子：
9.2
通讯作者：
Filatov, Dmitry A.
中科院分区：
文献类型：
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作者：
Krasovec, Marc;Chester, Michael;Filatov, Dmitry A.
性染色体进化的许多方面对植物和动物都是共同的[1]，但是Y染色体退化的过程，其中Y上的基因随着时间的推移变得无功能，在植物中可能会慢得多，这是由于对单倍体配子体中有害突变的纯化选择[2，3]。由于缺乏对植物性染色体年龄的准确估计，测试不同王国之间Y染色体退化的差异受到阻碍。本文利用基因组重测序技术对宽叶蝇子草（Silene latifolia）白色坎皮翁性染色体的自发突变率和年龄进行了估计。在亲本和10个F-1后代中筛选单核苷酸多态性（SNP），鉴定出39个从头突变，每个位点每个单倍体基因组每个世代的突变率为7.31 x 10（-9）（95%置信区间：5.20 x 10（-9）- 8.00 x 10（-9））。将此突变率应用于同源X-和Y-连锁基因（配子体）之间的同义分歧，得出老年和年轻地层的年龄估计分别为1100和632万年。基于SNP分离模式，我们推断哪些基因是Y连锁的，并发现至少47%已经功能失调。应用我们对性染色体年龄的新估计表明，S。与年龄相近的动物性染色体相比，阔叶树的性染色体几乎慢2倍。我们修订后的估计支持Y退化在植物中发生得更慢，这一差异可能是由动物和植物生命周期的差异所解释的。
Many aspects of sex chromosome evolution are common to both plants and animals [1], but the process of Y chromosome degeneration, where genes on the Y become non-functional over time, may be much slower in plants due to purifying selection against deleterious mutations in the haploid gametophyte [2, 3]. Testing for differences in Y degeneration between the kingdoms has been hindered by the absence of accurate age estimates for plant sex chromosomes. Here, we used genome resequencing to estimate the spontaneous mutation rate and the age of the sex chromosomes in white campion (Silene latifolia). Screening of single nucleotide polymorphisms (SNPs) in parents and 10 F-1 progeny identified 39 de novo mutations and yielded a rate of 7.31 x 10(-9) (95% confidence interval: 5.20 x 10(-9) - 8.00 x 10(-9)) mutations per site per haploid genome per generation. Applying this mutation rate to the synonymous divergence between homologous X- and Y-linked genes (gametologs) gave age estimates of 11.00 and 6.32 million years for the old and young strata, respectively. Based on SNP segregation patterns, we inferred which genes were Y-linked and found that at least 47% are already dysfunctional. Applying our new estimates for the age of the sex chromosomes indicates that the rate of Y degeneration in S. latifolia is nearly 2-fold slower when compared to animal sex chromosomes of a similar age. Our revised estimates support Y degeneration taking place more slowly in plants, a discrepancy that may be explained by differences in the life cycles of animals and plants.