Evolutionary strata on young mating-type chromosomes despite the lack of sexual antagonism
Evolutionary strata on young mating-type chromosomes despite the lack of sexual antagonism
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DOI：
10.1073/pnas.1701658114
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发表时间：
2017-07-03
影响因子：
11.1
通讯作者：
Giraud, Tatiana
中科院分区：
文献类型：
--
作者：
Branco, Sara;Badouin, Helene;Giraud, Tatiana
性染色体可以显示连续的重组抑制步骤，称为“进化层”，这被认为是由于性拮抗基因与性别决定基因的连续连锁。然而，几乎没有证据支持这一解释。在这里，我们调查是否进化阶层可以进化，没有性拮抗作用，使用真菌，显示抑制重组延伸到基因座以外，决定交配的兼容性，尽管缺乏男性/女性的角色与他们的交配类型。通过比较5个花药黑穗病真菌的染色体组装全长与重组抑制或不重组抑制在其交配型染色体，我们推断祖先基因的顺序和衍生的染色体排列在这组。这种方法揭示了真菌交配型基因座连锁的染色体融合，并为交配型染色体在一个年龄范围内（0.9- 210万年）的多个明确分辨的进化层提供了证据。有几个进化层次不包括与交配型决定有关的基因。缺乏交配型基因的层的存在，尽管缺乏性拮抗作用，要求性别相关的染色体进化的统一理论，包括，例如，部分连锁的有害突变的影响和中性重排多态性的维持，由于平衡选择性别和交配型。
Sex chromosomes can display successive steps of recombination suppression known as "evolutionary strata," which are thought to result from the successive linkage of sexually antagonistic genes to sex-determining genes. However, there is little evidence to support this explanation. Here we investigate whether evolutionary strata can evolve without sexual antagonism using fungi that display suppressed recombination extending beyond loci determining mating compatibility despite lack of male/female roles associated with their mating types. By comparing full-length chromosome assemblies from five anther-smut fungi with or without recombination suppression in their mating-type chromosomes, we inferred the ancestral gene order and derived chromosomal arrangements in this group. This approach shed light on the chromosomal fusion underlying the linkage of mating-type loci in fungi and provided evidence for multiple clearly resolved evolutionary strata over a range of ages (0.9-2.1 million years) in mating-type chromosomes. Several evolutionary strata did not include genes involved in mating-type determination. The existence of strata devoid of mating-type genes, despite the lack of sexual antagonism, calls for a unified theory of sex-related chromosome evolution, incorporating, for example, the influence of partially linked deleterious mutations and the maintenance of neutral rearrangement polymorphism due to balancing selection on sexes and mating types.