Background <p>Potato <i>(Solanum tuberosum</i>) breeding is severely hindered by its highly heterozygous autotetraploid genome, where complex allelic interactions impede precise trait selection. Reconstructing complete haplotype-resolved assemblies is crucial for genome-assisted breeding. However, current assembly methods for autopolyploids often generate fragmented sequences, haplotype-switch errors, and gaps in complex regions such as centromeres.</p> Results <p>To address these challenges, we develop PHap, a haplotype assembly pipeline tailored for autopolyploids, using only standard sequencing data, including long-reads and Hi-C. Applying PHap to the autotetraploid potato cultivar HuaShu4, we generate a haplotype-resolved, near telomere-to-telomere assembly of 3.12&#xa0;Gb with an N50 of 32.7&#xa0;Mb and 99.7% haplotype accuracy. Comparisons with alternative methods and existing assemblies highlight PHap’s advantages in assembly quality and cost-effectiveness. Integration of transcriptomic and epigenomic data demonstrates that the genomic and methylation divergence across haplotypes drives substantial allelic expression differentiation. Time-course RNA-seq further reveals, for the first time, that 55% of genes exhibit divergent allelic expression, with dynamic shifts in dominant or suppressed alleles during tuber development. Additionally, our assembly resolves high-resolution haplotype-specific structures in centromeres and subtelomeres, as well as haplotype divergence of structural rearrangements. It also shows neocentromere formation via the expansion of megabase-scale satellite arrays.</p> Conclusions <p>These findings provide insights into the architecture of autopolyploid genomes and establish a foundation for genomics-assisted breeding of polyploid potatoes.</p>

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Haplotype-resolved and near telomere-to-telomere assembly of the autotetraploid potato genome

  • Pei-Xuan Xiao,
  • Lei Tan,
  • Jianke Dong,
  • Jing Huang,
  • Yuhong Huang,
  • Jia-Bao He,
  • Handong Su,
  • Botao Song,
  • Wen-Biao Jiao

摘要

Background

Potato (Solanum tuberosum) breeding is severely hindered by its highly heterozygous autotetraploid genome, where complex allelic interactions impede precise trait selection. Reconstructing complete haplotype-resolved assemblies is crucial for genome-assisted breeding. However, current assembly methods for autopolyploids often generate fragmented sequences, haplotype-switch errors, and gaps in complex regions such as centromeres.

Results

To address these challenges, we develop PHap, a haplotype assembly pipeline tailored for autopolyploids, using only standard sequencing data, including long-reads and Hi-C. Applying PHap to the autotetraploid potato cultivar HuaShu4, we generate a haplotype-resolved, near telomere-to-telomere assembly of 3.12 Gb with an N50 of 32.7 Mb and 99.7% haplotype accuracy. Comparisons with alternative methods and existing assemblies highlight PHap’s advantages in assembly quality and cost-effectiveness. Integration of transcriptomic and epigenomic data demonstrates that the genomic and methylation divergence across haplotypes drives substantial allelic expression differentiation. Time-course RNA-seq further reveals, for the first time, that 55% of genes exhibit divergent allelic expression, with dynamic shifts in dominant or suppressed alleles during tuber development. Additionally, our assembly resolves high-resolution haplotype-specific structures in centromeres and subtelomeres, as well as haplotype divergence of structural rearrangements. It also shows neocentromere formation via the expansion of megabase-scale satellite arrays.

Conclusions

These findings provide insights into the architecture of autopolyploid genomes and establish a foundation for genomics-assisted breeding of polyploid potatoes.