The Barley Genome Sequence – Leveraging Next Generation Mapping as a Tool to Aid Assembly

Barley is one of the most important cereal crop species. It is a close relative to wheat and rye. Its haploid genome size exceeds 5 Gigabases (Gbp), almost twice the size of any fully sequenced organism or crop species. The International Barley Sequencing Consortium (IBSC) has come close to reach its 10 year milestone of a genome-wide BAC-by-BAC based genome sequence of barley. All seven barley chromosomes were sequenced based on short-read sequencing-by-synthesis technology along their respective minimum tiling path of the physical map. The biggest challenge remaining to be solved, however, was generating long range contiguity during scaffolding through those regions around the genetic centromeres, which are low in recombination. By employing 3D conformation capture sequencing (HiC) and Bionano genome mapping 4.6 Gbp of the 4.8 Gbp non-redundant sequences could be linearly ordered into seven pseudomolecules representing a first version (v1.0) reference sequence of the barley genome.