Domesticated some 10,000 years ago, barley has been a key crop since the dawn of agriculture. In this weekâs issue, Nils Stein and colleagues in the International Barley Sequencing Consortium report the sequencing and assembly of a reference genome for this important grain. They produced the genome for Hordeum vulgare L. by combining hierarchical shotgun sequencing of bacterial artificial chromosomes, genome mapping on nanochannel arrays and chromosome-scale scaffolding with conformation capture sequencing. The result is the first comprehensive, completely ordered assembly of the pericentromeric regions of a Triticeae genome â and it reveals that each of barleyâs seven chromosomes is divided into three compartments. The authors also sequenced and examined genetic diversity in the exomes of 96 European elite barley lines with a spring or winter growth habit, highlighting the potential utility of the sequence for cereal genomics and breeding programmes.