Genetic diversity, distribution and domestication history of the neglected GGAA genepool of wheat.

We present a comprehensive survey of cytogenetic and genomic diversity of the GGAA genepool of wheat, thereby unlocking these plant genetic resources for wheat improvement. Wheat yields are stagnating around the world and new sources of genes for resistance or tolerances to abiotic traits are required. In this context, the tetraploid wheat wild relatives are among the key candidates for wheat improvement. Despite its potential huge value for wheat breeding, the tetraploid GGAA genepool is largely neglected. Understanding the population structure, native distribution range, intraspecific variation of the entire tetraploid GGAA genepool and its domestication history would further its use for wheat improvement. The paper provides the first comprehensive survey of genomic and cytogenetic diversity sampling the full breadth and depth of the tetraploid GGAA genepool. According to the results obtained, the extant GGAA genepool consists of three distinct lineages. We provide detailed insights into the cytogenetic composition of GGAA wheats, revealed group- and population-specific markers and show that chromosomal rearrangements play an important role in intraspecific diversity of T. araraticum. The origin and domestication history of the GGAA lineages is discussed in the context of state-of-the-art archaeobotanical finds. We shed new light on the complex evolutionary history of the GGAA wheat genepool and provide the basis for an increased use of the GGAA wheat genepool for wheat improvement. The findings have implications for our understanding of the origins of agriculture in southwest Asia.