Department of Grassland Resources and Ecology, College of Grassland Science and Technology, China Agricultural University, Beijing, 100193, China.
Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada.
BMC Biol. 2024 May 1;22(1):102. doi: 10.1186/s12915-024-01902-4.
Sex-limited chromosomes Y and W share some characteristics, including the degeneration of protein-coding genes, enrichment of repetitive elements, and heterochromatin. However, although many studies have suggested that Y chromosomes retain genes related to male function, far less is known about W chromosomes and whether they retain genes related to female-specific function.
Here, we built a chromosome-level genome assembly of the Asian corn borer, Ostrinia furnacalis Guenée (Lepidoptera: Crambidae, Pyraloidea), an economically important pest in corn, from a female, including both the Z and W chromosome. Despite deep conservation of the Z chromosome across Lepidoptera, our chromosome-level W assembly reveals little conservation with available W chromosome sequence in related species or with the Z chromosome, consistent with a non-canonical origin of the W chromosome. The W chromosome has accumulated significant repetitive elements and experienced rapid gene gain from the remainder of the genome, with most genes exhibiting pseudogenization after duplication to the W. The genes that retain significant expression are largely enriched for functions in DNA recombination, the nucleosome, chromatin, and DNA binding, likely related to meiotic and mitotic processes within the female gonad.
Overall, our chromosome-level genome assembly supports the non-canonical origin of the W chromosome in O. furnacalis, which experienced rapid gene gain and loss, with the retention of genes related to female-specific function.
限性染色体 Y 和 W 具有一些共同特征，包括蛋白质编码基因的退化、重复元件的富集和异染色质。然而，尽管许多研究表明 Y 染色体保留了与男性功能相关的基因，但关于 W 染色体及其是否保留了与女性特有的功能相关的基因，人们知之甚少。
在这里，我们构建了一个亚洲玉米螟（Ostrinia furnacalis Guenée）的染色体水平基因组组装，这是玉米上一种重要的经济害虫，来自于一只雌性个体，包括 Z 和 W 染色体。尽管 Z 染色体在鳞翅目昆虫中深度保守，但我们的染色体水平 W 组装与相关物种中的可用 W 染色体序列或与 Z 染色体几乎没有保守性，这与 W 染色体的非典型起源一致。W 染色体积累了大量的重复元件，并从基因组的其余部分经历了快速的基因获得，大多数基因在复制到 W 染色体后发生了假基因化。保留显著表达的基因主要富集了 DNA 重组、核小体、染色质和 DNA 结合等功能，这可能与雌性性腺中的减数分裂和有丝分裂过程有关。
总的来说，我们的染色体水平基因组组装支持了亚洲玉米螟 W 染色体的非典型起源，它经历了快速的基因获得和丢失，保留了与女性特有的功能相关的基因。
