De novo assembly of the Pseudomonas syringae pv. syringae B728a genome using Illumina/Solexa short sequence reads.
Illumina's Genome Analyzer generates ultra-short sequence reads, typically 36 nucleotides in length, and is primarily intended for resequencing. We tested the potential of this technology for de novo sequence assembly on the 6 Mbp genome of Pseudomonas syringae pv. syringae B728a with several freely available assembly software packages. Using an unpaired data set, velvet assembled >96% of the genome into contigs with an N50 length of 8289 nucleotides and an error rate of 0.33%. EDENA generated smaller contigs (N50 was 4192 nucleotides) and comparable error rates. SSAKE and VCAKE yielded shorter contigs with very high error rates. Assembly of paired-end sequence data carrying 400 bp inserts produced longer contigs (N50 up to 15 628 nucleotides), but with increased error rates (0.5%). Contig length and error rate were very sensitive to the choice of parameter values. Noncoding RNA genes were poorly resolved in de novo assemblies, while >90% of the protein-coding genes were assembled with 100% accuracy over their full length. This study demonstrates that, in practice, de novo assembly of 36-nucleotide reads can generate reasonably accurate assemblies from about 40 x deep sequence data sets. These draft assemblies are useful for exploring an organism's proteomic potential, at a very economic low cost.
Farrer
Rhys A
RA
The Sainsbury Laboratory, Colney Lane, Norwich, UK.
Kemen
Eric
E
Jones
Jonathan D G
JD
Studholme
David J
DJ
D002874:Chromosome Mapping / Q000379:methods*; D019295:Computational Biology; D016680:Genome, Bacterial; D044224:Pseudomonas syringae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012984:Software