Genome assembly of the rare and endangered Grantham's camellia, Camellia granthamiana.

Abstract

Grantham's camellia (Camellia granthamiana Sealy) is a rare and endangered tea species discovered in Hong Kong in 1955 and endemic to southern China. Despite its high conservation value, the genomic resources of C. granthamiana are limited. Here, we present a chromosome-scale draft genome of the tetraploid C. granthamiana (2n = 4x =60), combining PacBio long-read sequencing and Omni-C data. The assembled genome size is ∼2.4Gb, with most sequences anchored to 15 pseudochromosomes resembling a monoploid genome. The genome has high contiguity, with a scaffold N50 of 139.7 Mb, and high completeness (97.8% BUSCO score). Our gene model prediction resulted in 68,032 protein-coding genes (BUSCO score of 90.9%). We annotated 1.65Gb of repeat content (68.48% of the genome). Our Grantham's camellia genome assembly is a valuable resource for investigating Grantham's camellia's biology, ecology, and phylogenomic relationships with other Camellia species, and provides a foundation for further conservation measures.