Validation of PacBio and NRgene Maize Genome Assemblies by BioNano Genome Mapping

Two maize genomes have recently been assembled using next generation methodologies. The genome of the inbred B73 (version 4) was assembled using PacBio SMRT sequencing, while the genome of the inbred W22 was assembled using Illumina sequencing and NRgene DeNovoMAGIC algorithms. Both the B73 and W22 assemblies were independently assessed using BioNano Irys optical mapping technology. The sequence assemblies are extremely accurate, showing >99% alignment with the BioNano optical maps. Conflicts in collinearity between the sequence and optical maps from the same inbred are extremely rare, but there are thousands of small (~ less than 10 kb) disagreements that appear as apparent insertions or deletions in the comparisons. These errors may be attributed to either technology but most appear to be associated with the sequence assemblies.