Chromosome-level assemblies of cultivated water chestnut Trapa bicornis and its wild relative Trapa incisa.

Water chestnut (Trapa L.) is a floating-leaved aquatic plant with high edible and medicinal value. In this study, we presented chromosome-level genome assemblies of cultivated large-seed species Trapa bicornis and its wild small-seed relative Trapa incisa by using PacBio HiFi long reads and Hi-C technology. The T. bicornis and T. incisa assemblies consisted of 479.90 Mb and 463.97 Mb contigs with N50 values of 13.52 Mb and 13.77 Mb, respectively, and repeat contents of 62.88% and 62.49%, respectively. A total of 33,306 and 33,315 protein-coding genes were predicted in T. bicornis and T. incisa assemblies, respectively. There were 159,232 structural variants affecting more than 11 thousand genes detected between the two genomes. The phylogenetic analysis indicated that the lineage leading to Trapa was diverged from the lineage to Sonneratia approximately 23 million years ago. These two assemblies provide valuable resources for future evolutionary and functional genomic research and molecular breeding of water chestnut.