Hu, Y.; Huang, Y.; Yong, Y.; Shang, E.; Zhang, B.; Sui, Z.

As an important cultivated red alga, Gracilariopsis lemaneiformis has great economic and ecological value. However, its existing genome assembly is highly fragmented and inadequately annotated. In this study, we constructed the first high-quality chromosome-level genome of Gp. lemaneiformis using PacBio long reads, Illumina short reads and Hi-C sequencing data. The assembled genome was approximately 86.66 Mb and the assembled sequences were anchored to 28 pseudo-chromosomes with lengths ranging from 1.70 to 7.81 Mb. 99.91% of the PacBio reads could be mapped to our assembly. In total, 8,664 genes were annotated, and the repeat elements identified in Gp. lemaneiformis constituted 63.88% of the whole genome, including 2.24% tandem repeat sequences and 61.64% interspersed repeats. We also established a high-evidence phylogenetic tree from 19 representative algae species, with the main aim to calculate their divergence times. This high-quality genome of Gp. lemaneiformis provides a crucial foundation for understanding genetic characteristics, investigating the genomic evolution, and facilitating molecular breeding.