Aegilops tauschii single nucleotide polymorphisms shed light on the origins of wheat D-genome genetic diversity and pinpoint the geographic origin of hexaploid wheat
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- Hexaploid wheat (Triticum aestivum, genomes AABBDD) originated by hybridization of tetraploid Triticum turgidum (genomes AABB) with Aegilops tauschii (genomes DD). Genetic relationships between A. tauschii and the wheat D genome are of central importance for the understanding of wheat origin and subsequent evolution.
- Genetic relationships among 477 A. tauschii and wheat accessions were studied with the A. tauschii 10K Infinium single nucleotide polymorphism (SNP) array.
- Aegilops tauschii consists of two lineages (designated 1 and 2) having little genetic contact. Each lineage consists of two closely related sublineages. A population within lineage 2 in the southwestern and southern Caspian appears to be the main source of the wheat D genome. Lineage 1 contributed as little as 0.8% of the wheat D genome. Triticum aestivum is subdivided into the western and Far Eastern populations. The Far Eastern population conserved the genetic make-up of the nascent T. aestivum more than the western population. In wheat, diversity is high in chromosomes 1D and 2D and it correlates in all wheat D-genome and A. tauschii chromosomes with recombination rates.
- Gene flow from A. tauschii was an important source of wheat genetic diversity and shaped its distribution along the D-genome chromosomes.