A Chromosome-Level Genome Assembly and Annotation of the Chinese Porcupine (Hystrix hodgsoni) Reveals the Expansion of Olfactory-Related Gene Families

Background/Objectives: The Chinese porcupine (Hystrix hodgsoni) is a distinctive rodent species characterized by specialized ecological adaptations and sensory traits; however, genomic resources for this species have remained limited. This study aims to provide a reliable reference for comparative and evolutionary analyses by constructing a high-quality genome. Methods: We generated a chromosome-level genome assembly of the Chinese porcupine using long-read sequencing combined with chromatin conformation-based scaffolding, followed by comprehensive structural and functional annotation. Comparative genomic analyses across representative mammals and functional enrichment analyses were conducted to investigate lineage-specific gene family dynamics. Results: The assembled genome shows high contiguity and completeness. Comparative analyses revealed a substantial number of gene families significantly expanded along the porcupine lineage. Functional enrichment demonstrated strong overrepresentation of olfactory-related processes, including olfactory receptor activity, odorant binding, and detection of chemical stimuli. Additionally, several expanded families were associated with epidermal differentiation, keratinization, and skin development. Conclusions: Gene family expansions in the Chinese porcupine are biased toward sensory perception and epidermal functions, suggesting potential genetic bases for its enhanced environmental sensing and integumentary specialization. This assembly provides an important genomic resource for porcupine research and new insights into the molecular mechanisms underlying sensory and skin-related adaptations in rodents.