Chromosome sorting and its applications in common wheat (Triticum aestivum) genome sequencing

The large genome size (∼17000 Mb) and complicated DNA structures of common wheat (Triticum aestivum) hamper its genome sequencing. By means of flow cytometry, systematic investigations on individual chromosome sorting have been carried out to construct chromosome-specific bacterial artificial chromosome (BAC) libraries since the 1980s. Several wheat chromo-some-specific BAC libraries, such as chromosome 3B, three D genome chromosomes (1D, 4D and 6D), and the short arm of chromosome 1B, have been developed, and the physical map of chromosome 3B was established in 2008. The same chromosome-based strategy is being employed by the International Wheat Genome Sequencing Consortium (IWGSC) to establish the physical maps of the other 20 common wheat chromosomes (cv. Chinese Spring). Several projects on wheat genome sequencing are currently underway. The availability of new sequencing technologies provides new choices for sequencing of gene space of the wheat genome. The applications of flow-sorted chromosomes in wheat genome studies present some examples to analyze the complex genomes of cereals.