Chromosome-Level Genome Assembly of Ormosia henryi Provides Insights into Evolutionary Resilience and Precision Conservation

TL;DR

A high-quality genome assembly of Ormosia henryi reveals its evolutionary history and genetic traits, aiding conservation and sustainable use.

Contribution

A chromosome-level genome assembly of Ormosia henryi, revealing evolutionary resilience and key genes for conservation.

Findings

The genome assembly shows high continuity and completeness despite high heterozygosity and repetitive sequences.

Comparative analysis reveals two whole-genome duplications and divergence from Lupinus albus 53.82 million years ago.

Expanded gene families and positively selected genes highlight resilience traits and DNA repair mechanisms.

Abstract

Ormosia henryi, a rare and endemic timber tree in China, possesses exceptional economic and ecological value, but it has experienced a critical decline in wild populations. We integrated PacBio HiFi and Hi-C technologies to generate a superior, chromosome-level genome assembly, establishing a more robust genetic foundation than existing draft sequences. The resulting assembly (2.64 Gb; Contig N50 = 39.17 Mb; and Scaffold N50 = 338.40 Mb) exhibits high continuity and completeness, effectively overcoming the assembly challenges associated with high heterozygosity (1.37%) and repetitive sequence content (83.89%). Comparative genomic analysis revealed that O. henryi diverged from Lupinus albus approximately 53.82 million years ago and underwent two independent whole-genome duplication events. The historical accumulation of evolutionary resilience is reflected in the significant expansion of 276 gene families enriched in photosynthesis and phenylpropanoid biosynthesis, alongside 122 genes under positive selection involved in DNA repair and proteostasis. These genomic signatures elucidate a stable genetic foundation. While wild populations have sharply declined in recent decades, this suggests that this status underscores the overwhelming impact of intense external anthropogenic pressures, such as overexploitation and habitat fragmentation, which may have overridden the species’ inherent adaptive capacity and slow life-history strategy. This high-quality genomic resource identifies key candidate loci, such as the PIF1 helicase for growth regulation, and provides a critical framework for screening elite germplasm for population restoration. Consequently, this study establishes a theoretical and molecular basis for transitioning from fundamental research to the precision conservation and sustainable industrial application of this high-value woody species.

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