Advances in sequencing the barley genome

Barley genome sequencing is lagging behind the status achieved for many other crop genomes although barley is ranking worldwide as fifth most important crop species. Whole genome sequencing of barley with classical Sanger sequencing technology was long meant to be too costly due to the very large genome size of more than 5 Gigabases. By the introduction of Next Generation Sequencing technology this situation has changed and fascinating new possibilities opened up for in depth barley genome analysis and whole genome sequencing. Genome composition has been revealed at unprecedented resolution. A linear gene order map comprising two thirds of all barley genes could be developed and the approach is currently adopted for other related and important cereal genomes like wheat and rye. Important technical limitations have been solved making even whole genome sequencing in barley a feasible endeavor. Provided these new possibilities, it is becoming obvious that soon sequencing per se is no longer the limiting factor but sequence assembly remains the challenge. This review will provide a brief summary of the recent developments in barley genome sequencing achieved since the introduction of Next Generation Sequencing.