Towards Functional Durum Wheat Genome Assembly

Genome sequencing using whole-genome shotgun strategy usually fails to provide a linear order of contigs along individual chromosomes, especially in complex genomes. It was recently shown that sequencing progeny of a segregating population in barley allowed de novo production of a genetically anchored linear assembly of the gene space. As a step towards achieving such functional durum wheat genome assembly we hybridized wild emmer wheat (T. turgidum ssp dicoccoides, genomes BBAA) with durum wheat (T. turgidum ssp durum, cv. Svevo), and developed an F₆ recombinant inbred line (RIL) population. We have constructed a genetic map with  939,536 markers clustered to 3,732 recombination bins and 14 chromosomes by using a novel genotyping by sequencing (GBS) approach and the wheat 90K iSelect SNP genotyping assay. We further compared all the short sequences produced by the GBS procedure to the recent draft sequence of the wheat A genome progenitor T. urartu and anchored 26,116 scaffolds to the seven A genome chromosomes of tetraploid wheat. The total length of the anchored T. urartu scaffolds was ~2Gb (~40% of T. urartu genome) corresponding to 104,191 A genome markers (~24% of total A markers). These results demonstrate the utility of our approach for the construction of functional draft linear assembly of complex genomes.