HiRise Scaffolding Report


August 03, 2023

Theobroma cacao

Lyndel Meinhardt

USDAARS Sustainable Perennial Crops Lab


Contents

Overview

Assembly Total Length (bp) N50 L50 N90 L90
Input Assembly 423,200,203 23,790,132 6 8,850,526 16
Dovetail HiRise Assembly 423,202,184 42,765,999 5 29,066,853 10

Contiguity Metrics

Input Assembly Dovetail HiRise Assembly
Largest scaffold 46,820,523 46,855,655
Number of scaffolds 360 357
Number of scaffolds > 1kbp 360 357
Number of gaps 0 12
Number of N's per 100 kbp 0.00 0.47

BUSCO

Assembly Complete BUSCOs (C) Complete and single-copy BUSCOs (S) Complete and duplicated BUSCOs (D) Fragmented BUSCOs (F) Missing BUSCOs (M) Total BUSCO groups searched
Input Assembly 248 (97.25%) 236 (92.55%) 12 3 4 255
Dovetail HiRise Assembly 249 (97.65%) 237 (92.94%) 12 2 4 255

Pair Size Distribution

HiRise Scaffolding Information

Number of joins made by HiRise 12
Number of breaks made to input assembly by HiRise 3
Read-pairs 35,830,229

Materials and Methods

Dovetail Omni-C Library Preparation and Sequencing

For each Dovetail Omni-C library, chromatin was fixed in place with formaldehyde in the nucleus and then extracted. Fixed chromatin was digested with DNAse I, chromatin ends were repaired and ligated to a biotinylated bridge adapter followed by proximity ligation of adapter containing ends. After proximity ligation, crosslinks were reversed and the DNA purified. Purified DNA was treated to remove biotin that was not internal to ligated fragments. Sequencing libraries were generated using NEBNext Ultra enzymes and Illumina-compatible adapters. Biotin-containing fragments were isolated using streptavidin beads before PCR enrichment of each library. The library was sequenced on an Illumina HiSeqX platform to produce a approximately 30x sequence coverage. Then HiRise used MQ>50 reads for scaffolding (see "read-pair" above for figures).

Scaffolding the Assembly with HiRise

The input de novo assembly and Dovetail OmniC library reads were used as input data for HiRise, a software pipeline designed specifically for using proximity ligation data to scaffold genome assemblies (Putnam et al, 2016). Dovetail OmniC library sequences were aligned to the draft input assembly using bwa (https://github.com/lh3/bwa). The separations of Dovetail OmniC read pairs mapped within draft scaffolds were analyzed by HiRise to produce a likelihood model for genomic distance between read pairs, and the model was used to identify and break putative misjoins, to score prospective joins, and make joins above a threshold.


References

1. Putnam NH, O'Connell BL, Stites JC, Rice BJ, Blanchette M, Calef R, Troll CJ, Fields A, Hartley PD, Sugnet CW, Haussler D, Rokhsar DS, Green RE. Genome Research. 2016 Mar;26(3):342-50.