Abstract: The green odorous frog (Odorrana margaretae) represents an excellent model system for investigating the genetic basis of anuran skin secretions. Here, we report a chromosome-level genome assembly comprising 13 chromosomes with a total size of 6.20 Gb. Within this large genome, approximately 4.78 Gb (77.01%) consists of repetitive elements, with evidence of recent rapid expansions of DNA transposons and long terminal repeats (LTRs). Comparative gene family analyses identified 154 significantly expanded gene families in the green odorous frog, predominantly associated with innate immune functions. Targeted data mining revealed a diverse repertoire of antimicrobial peptides (AMPs), characterized by a massive expansion of histone-derived AMP copies organized into large tandem clusters. Additionally, the genome harbors an extensive array of olfaction-related genes, including 1,035 functional olfactory receptor (OR) genes, with notable expansions in the α and γ subfamilies responsible for detecting airborne odors; transposable elements (TEs) are significantly enriched in the flanking regions of these OR genes. The species also exhibits a signature of tandem duplication in trace amine-associated receptor 2 (TAAR2) genes. Collectively, these findings suggest enhanced capabilities in odor detection and chemical communication, likely linked to its skin secretions. This high-quality reference genome provides a foundation for future studies on the genetic regulation of potent skin secretions in this species and other amphibians.

Key words: Chromosome-level genome assembly, comparative genomics, Odorrana margaretae, transposon expansion, odor adaptation