Gap-free telomere-to-telomere haplotype assembly of the tomato hind (Cephalopholis sonnerati)

The tomato hind (Cephalopholis sonnerati) is an emerging economically important grouper in recent years. With the increasing maturity of sequencing technologies and assembly methodologies, a higher quality reference genome has become both accessible and necessary. In this study, we present two telomere-to-telomere (T2T) gap-free haplotype assemblies of the tomato hind with lengths of 1039.53 Mb (YSFRI_Csonn_HA_1.0, N50 43.83 Mb) and 1039.91 Mb (YSFRI_Csonn_HB_1.0, N50 44.09 Mb). Reads from next-generation sequencing, ONT ultra-long sequencing, and PacBio HiFi sequencing exhibited mapping rates exceeding 99.8% when aligned to these two assemblies. Evaluation using Merqury indicated high accuracy for both assemblies, with average quality values of 51.80 and 51.83, respectively. Percentages of 97.9% and 97.8% of complete BUSCOs were achieved, and a total of 23,270 and 23,184 protein-code genes were inferred in each assembly. Moreover, telomere identification, centromere prediction, and repetitive sequence annotation were also successfully performed. These two assemblies provide robust foundation for the genetic analysis and development of molecular genetic breeding technologies in C. sonnerati.