A telomere-to-telomere genome assembly of Castanopsis orthacantha (Fagaceae)

This study reported the first telomere-to-telomere (T2T) genome assembly of Castanopsis orthacantha , a keystone tree species with significant ecological and economic values endemic to the subtropical evergreen forests of southwestern China. Using multi-platform sequencing data and high-throughput chromosome conformation capture (Hi-C) scaffolding, we successfully generated a chromosome-scale assembly. The final assembly spanned 893.28 Mb, with a contig N50 of 76.19 Mb, indicating a high degree of continuity. Remarkably, 97.94% of the genome was successfully anchored to 12 chromosomes. Terminal telomeric repeat sequences were identified at both ends of all of the chromosomes, and the assembly contained only a single unresolved gap. A total of 35,978 protein-coding genes were detected in the assembly, with an average coding sequence (CDS) length of 1,116.3 bp. Genomic analysis further revealed that repetitive elements comprised 59.28% of the genome. The generation of this near-complete reference genome of C. orthacantha provides a critical genomic resource for advancing evolutionary study within the Fagaceae family and supports conservation genomics strategies aimed at the ecological restoration of this species.