The IWGSC Bread Wheat Survey Sequencing Initiative

The large size (17Gb) and complexity of the bread wheat genome, an allohexaploid with 6n=42 chromosomes derived from three grass genomes (AA,BB,DD) have posed severe challenges for the development of genomic resources that will facilitate wheat breeding improvements.   To reduce the complexity of sequence assembly and chromosome assignment for this genome,  the international wheat community have agreed to produce a breadwheat reference sequence  based on physical maps and sequence data for individual chromosomes flow-sorted from aneuploid cell lines of the reference variety, Chinese Spring 42.  In the last year, a survey sequence resource for the genome has been produced by sequencing to a depth of >=30-fold paired end Illumina libraries prepared from DNA amplified from individual chromosome arms. After trimming poor quality data, sequence assemblies were generated using AbySS and subjected to analyses that have included comparison of gene content and organization within and between homoeologous chromosomes. Using a large RNASeq data set collected from different tissues it has also been possible to gain an unprecedented overview of the transcriptional activity of the genome.