Genome sequencing and assembly
The diploid Tiarella polyphylla (2n = 2x = 14;Fig. 1-B, C ) genome size was estimated to be 393.29 Mb based on the total number of 20,057,799,129 21-mer and a peak 21-mer depth of 51, and the estimated heterozygosity rate was approximately 0.273% (Fig. S1; Table S3 ). A total of 65.3 Gb of ONT (Oxford Nanopore Technology) reads was produced with an N50 of 30.0 kb from one PromethION R9.4.1 flow cell. The longest ONT read was 219.8 kb, and the genome coverage was c. ×162 (Table S4 ). We trimmed the raw reads using the CANU software, and the corrected reads were assembled for resulting in an initial assembly with a genome size of ~ 404.3 Mb and a contig N50 of ~11.5 Mb (Table 1 ). After polishing using NextPolish, we retrieved a corrected genome with size 418.1 Mb and contig N50 12.0 Mb. Finally, after removing sequences originating from the plastome, the mitochondrial genome and bacteria, the de novo genome assembly was 412.2 Mb in size, with contig N50, longest contig, and contig number of 12.0 Mb, 26.3 Mb and 206, respectively.