Assembly improvement with increasing coverage and read length. Simulated assembly results on all complete NCBI references as of January 2013 using PacBio RS C1, C2, XL-C2, XL-XL, and projected 'ZL’ chemistries. The two figures show the percentage of genomes closed (left) and the average number of remaining gaps (right) with increasing sequencing coverage. C2 and newer chemistries can span the rDNA repeat and thus close many more genomes than the C1 chemistry. However, beyond 150× C2 there is limited benefit from further sequencing because the remaining repeats are too long to resolve. The longer chemistries saturate most repeats and gain little benefit from additional coverage over 50×. Resolving the remaining repeats requires a jump in sequence length to hundreds of kilobases.
Koren et al. Genome Biology 2013 14:R101 doi:10.1186/gb-2013-14-9-r101