We present a high‐quality genome assembly for the Asiatic toad (Bufo gargarizans) and explore the evolution of several large gene families in amphibians. With a large genome assembly size of 4.55 Gb, the chromosome‐scale assembly includes 747 scaffolds with an N50 of 539.8 Mb and 1.79% gaps. Long terminal repeats (LTRs) constitute a high proportion of the genome and their expansion is a key contributor to the inflated genome size in this species. This is very different from other small amphibian genomes, but similar to that of the enormous axolotl genome. The genome retains a large number of duplicated genes, with tandem (TD) and proximal duplications (PD) the predominant mode of duplication. A total of 122 gene families have undergone significant expansion and were mainly enriched in sensory perception of smell and bitter taste. The CYP2C subfamily, which plays an important role in metabolic detoxification, specifically expanded via TD and PD in the Asiatic toad and the cane toad (true toads). Most of Na⁺/K⁺‐ATPase genes experienced accelerated evolution along Bufonid lineages and two amino acid sites involving toad‐toxin resistance were found to experience positive selection. We also revealed a dynamic evolution of olfactory and vomeronasal receptor gene families which was likely driven by the water‐to‐land transition. The high‐quality genome of the Asiatic toad will provide a solid foundation to understand the genetic basis of its many biological processes.

中文翻译：

---

具有染色体规模组装的大型基因组揭示了真正蟾蜍（Bufo gargarizans）的进化成功

我们为亚洲蟾蜍（Bufo gargarizans) 并探索两栖动物中几个大基因家族的进化。基因组组装大小为 4.55 Gb，染色体规模组装包括 747 个支架，N50 为 539.8 Mb，间隙为 1.79%。长末端重复序列 (LTR) 占基因组的很大一部分，它们的扩展是该物种基因组大小膨胀的关键因素。这与其他小型两栖动物基因组非常不同，但与巨大的蝾螈基因组相似。基因组保留了大量重复基因，其中串联 (TD) 和近端重复 (PD) 是主要的重复模式。共有122个基因家族经历了显着扩展，主要富集了嗅觉和苦味的感官知觉。该CYP2C亚科在代谢解毒中起重要作用，特别是通过亚洲蟾蜍和甘蔗蟾蜍（真蟾蜍）的 TD 和 PD 扩大。大多数 Na ⁺ /K ⁺ -ATPase 基因沿着 Bufonid 谱系经历了加速进化，并且发现两个涉及蟾蜍毒素抗性的氨基酸位点经历了正选择。我们还揭示了嗅觉和犁鼻受体基因家族的动态进化，这可能是由水陆过渡驱动的。亚洲蟾蜍的高质量基因组将为了解其许多生物过程的遗传基础提供坚实的基础。