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Fast and accurate long-read assembly with wtdbg2

Abstract

Existing long-read assemblers require thousands of central processing unit hours to assemble a human genome and are being outpaced by sequencing technologies in terms of both throughput and cost. We developed a long-read assembler wtdbg2 (https://github.com/ruanjue/wtdbg2) that is 2–17 times as fast as published tools while achieving comparable contiguity and accuracy. It paves the way for population-scale long-read assembly in future.

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Fig. 1: Outline of the wtdbg2 algorithm. Wtdbg2 groups 256 bp into a bin, a small box in the figure.

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Data availability

C. elegans and A. thaliana Ler-0 reads are available at the PacBio public datasets portal: http://bit.ly/pbpubdat. We downloaded SRR5439404 for the D. melanogaster A4 strain, SRR6702603 for the D. melanogaster reference ISO1 strain, ERR2571284 through ERR2571302 for M. schizocarpa (banana; MinION reads only), PRJNA378970 for axolotl, SRR7615963 for HG00733, and ERR2631600 and ERR2631601 for NA19240. CHM1 reads were acquired from SRP044331 (http://bit.ly/chm1p6c4 for raw signals), NA12878 reads from http://bit.ly/na12878ont (release 5) and NA24385 from http://bit.ly/NA24385ccs. For the A. thaliana Col-0/Cvi-0 dataset, the FASTQ files at SRA (AC, PRJNA314706) were not processed properly. J. Chin, the first author of the paper1 describing the dataset, provided us with reprocessed raw reads, which are now hosted at public file transfer protocol (FTP) site ftp://ftp.dfci.harvard.edu/pub/hli/col0-cvi0/. The CHM1 CANU and FALCON assemblies and the axolotl assembly are available at NCBI (GCA_000983455.1, GCA_001297185.1 and GCA_002915635.1, respectively). All the evaluated assemblies generated by us can be obtained at ftp://ftp.dfci.harvard.edu/pub/hli/wtdbg/. The FTP site also provides the detailed command lines and the FALCON configuration files.

Code availability

The wtdbg2 source code is hosted by GitHub at: https://github.com/ruanjue/wtdbg2.

References

  1. Chin, C. S. et al. Phased diploid genome assembly with single-molecule real-time sequencing. Nat. Methods 13, 1050–1054 (2016).

    Article  CAS  Google Scholar 

  2. Kolmogorov, M., Yuan, J., Lin, Y. & Pevzner, P. A. Assembly of long, error-prone reads using repeat graphs. Nat. Biotechnol. 37, 540–546 (2019).

    Article  CAS  Google Scholar 

  3. Koren, S. et al. Canu: scalable and accurate long-read assembly via adaptive k-mer weighting and repeat separation. Genome Res. 27, 722–736 (2017).

    Article  CAS  Google Scholar 

  4. Li, H. Minimap and miniasm: fast mapping and de novo assembly for noisy long sequences. Bioinformatics 32, 2103–2110 (2016).

    Article  CAS  Google Scholar 

  5. Xiao, C. L. et al. MECAT: fast mapping, error correction, and de novo assembly for single-molecule sequencing reads. Nat. Methods 14, 1072–1074 (2017).

    Article  CAS  Google Scholar 

  6. De Coster, W. et al. Structural variants identified by Oxford Nanopore PromethION sequencing of the human genome. Genome Res. 29, 1178–1187 (2019).

    Article  CAS  Google Scholar 

  7. Myers, G. Efficient local alignment discovery amongst noisy long reads. in WABI vol. 8701. (eds. D. G. Brown & B. Morgenstern) 52–67, https://doi.org/10.1007/978-3-662-44753-6_5 (Springer, 2014).

  8. Berlin, K. et al. Assembling large genomes with single-molecule sequencing and locality-sensitive hashing. Nat. Biotechnol. 33, 623–630 (2015).

    Article  CAS  Google Scholar 

  9. Li, H. Minimap2: pairwise alignment for nucleotide sequences. Bioinformatics 34, 3094–3100 (2018).

    Article  CAS  Google Scholar 

  10. Chaisson, M. J., Wilson, R. K. & Eichler, E. E. Genetic variation and the de novo assembly of human genomes. Nat. Rev. Genet. 16, 627–640 (2015).

    Article  CAS  Google Scholar 

  11. Smith, T. F. & Waterman, M. S. Identification of common molecular subsequences. J. Mol. Biol. 147, 195–197 (1981).

    Article  CAS  Google Scholar 

  12. Ye, C., Ma, Z. S., Cannon, C. H., Pop, M. & Yu, D. W. Exploiting sparseness in de novo genome assembly. BMC Bioinforma. 13(Suppl 6), S1 (2012).

    Article  Google Scholar 

  13. Zerbino, D. R. & Birney, E. Velvet: algorithms for de novo short read assembly using de Bruijn graphs. Genome Res. 18, 821–829 (2008).

    Article  CAS  Google Scholar 

  14. Lee, C., Grasso, C. & Sharlow, M. F. Multiple sequence alignment using partial order graphs. Bioinformatics 18, 452–464 (2002).

    Article  CAS  Google Scholar 

  15. Belser, C. et al. Chromosome-scale assemblies of plant genomes using nanopore long reads and optical maps. Nat. Plants 4, 879–887 (2018).

    Article  CAS  Google Scholar 

  16. Chin, C. S. et al. Nonhybrid, finished microbial genome assemblies from long-read SMRT sequencing data. Nat. Methods 10, 563–569 (2013).

    Article  CAS  Google Scholar 

  17. Watson, M. & Warr, A. Errors in long-read assemblies can critically affect protein prediction. Nat. Biotechnol. 37, 124–126 (2019).

    Article  CAS  Google Scholar 

  18. Jain, M. et al. Nanopore sequencing and assembly of a human genome with ultra-long reads. Nat. Biotechnol. 36, 338–345 (2018).

    Article  CAS  Google Scholar 

  19. Nowoshilow, S. et al. The axolotl genome and the evolution of key tissue formation regulators. Nature 554, 50–55 (2018).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We are grateful to J. Chin for providing the properly processed raw reads for the A. thaliana Col-0/Cvi-0 dataset. We thank C. Ye from University of Maryland for frequent and fruitful discussion in the development of wtdbg and thank A. Li and S. Wu from CAAS for the help in polishing assemblies. We also thank the reviewers whose comments have helped us to improve wtdbg2. This study was supported by Natural Science Foundation of China (grant nos. 31571353 and 31822029 to J.R.) and by the US National Institutes for Health (grant no. R01-HG010040 to H.L.).

Author information

Authors and Affiliations

Authors

Contributions

J.R. conceived the project, designed the algorithm and implemented wtdbg2. H.L. contributed to the development and drafted the manuscript. Both authors evaluated the results and revised the manuscript.

Corresponding authors

Correspondence to Jue Ruan or Heng Li.

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Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nicole Rusk and Lin Tang were the primary editors on this article and managed its editorial process and peer review in collaboration with the rest of the editorial team.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Table 1

Evaluation of long-read assemblies: FALCON requires PacBio-style read names and does not work with ONT data or the A4 strain of D. melanogaster that was downloaded from SRA. The A. thaliana assembly by FALCON is acquired from PacBio website as our assembly is fragmented. MECAT produces fragmented assemblies for the ONT dataset. Human assemblies were performed by the developers of each assembler. Base-level evaluations and NGA50 are only reported when the sequenced strain or individual is close to the reference genome. BUSCO scores are computed for genomes sequenced to 50-fold coverage or higher.

Reporting Summary

Supplementary Data

The FALCON configure file for assembling C. elegans.

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Ruan, J., Li, H. Fast and accurate long-read assembly with wtdbg2. Nat Methods 17, 155–158 (2020). https://doi.org/10.1038/s41592-019-0669-3

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