Assembly quality for varying read lengths.

Human chr21 (34.2 Mb), Total error rate = 1.0%
We varied the average read length from 100 to 300 bp and assembled human chromosome 21 at 11.25x and 20.0x coverage to assess the impact of read length on assembly quality. At read lengths of 100–150 bp we observed lower levels of sequence coverage and smaller contig sizes. With 200 bp we achieved good draft coverage with large contig sizes and few misassemblies. Increasing the read length further to 250 bp yielded significant gains while 300 bp did not provide much additional improvement. Interestingly, keeping the read length constant at 200 bp and increasing the coverage from 11.25x to 20.0x produced greater assembly quality gains than increasing the read length from 200 to 300 bp.