Chromosome-scale and haplotype-resolved genome assembly of a tetraploid potato cultivar

Potato is the most widely produced tuber crop worldwide. However, reconstructing the four haplotypes of its autotetraploid genome remained an unsolved challenge. Here,we report the 3.1Gb haplotype-resolved (at 99.6% precision), chromosome-scale assembly of the potato cultivar 'Otava' based on high-quality long reads, single-cell sequencing of 717 pollen genomes and Hi-C data. Unexpectedly, similar to 50% of the genome was identical-by-descent due to recent inbreeding, which was contrasted by highly abundant structural rearrangements involving similar to 20% of the genome. Among 38,214 genes, only 54% were present in all four haplotypes with an average of 3.2 copies per gene. Taking the leaf transcriptome as an example, 11% of the genes were differently expressed in at least one haplotype, where 25% of them were likely regulated through allele-specific DNA methylation. Our work sheds light on the recent breeding history of potato, the functional organization of its tetraploid genome and has the potential to strengthen the future of genomics-assisted breeding.

Automated summary

This study reports the reconstruction of the autotetraploid genome of potato based on high-quality long reads, single-cell sequencing, and Hi-C data, revealing the characteristics of genome similarity and structural rearrangements caused by recent inbreeding. Only a portion of the genes were present in all four haplotypes, and some genes may be regulated through allele-specific DNA methylation.