Chromosome 1B: A Step Further in the Sequencing of the Hexaploid Wheat Genome

Because of its size (17 Gb), allohexaploid (AABBDD) and highly repeat content, the wheat genome has long been perceived as too complex to be sequenced. To overcome these limitations, the IWGSC established a strategy based on chromosome sorting and physical mapping to sequence each individual chromosome through a BAC-by-BAC approach. The recent publication of the first reference sequence of the bread wheat (Triticum aestivum) chromosome 3B (Choulet et al.2014) not only represents a major technological achievement but also demonstrates the feasibility of this approach, therefore paving the way for the sequencing of the entire wheat genome. Thanks to the expertise gained through this project as well as to the recent developments in sequencing technologies, we designed an improved strategy to complete the sequencing of the genome in a more time- and cost-efficient way. In addition, we developed complementary approaches to improve the initial assembly. This strategy is currently being used to sequence two wheat chromosomes: 1B and 4B. Here we report on this new sequencing strategy as well as on the first results obtained for the long arm of chromosome 1B.

Choulet et al., Science, 2014 Jul 18;345(6194):1249721