The Rising Influence of Bread Dough on Civilization

According to Professor Brande Wulff, a wheat researcher at KAUST (King Abdullah University of Science and Technology) and one of the main authors of the study published in Nature, “Our research provides fresh insights into a key event in our civilization that gave rise to a new agricultural system, enabling human settlements and societal development.”

Professor Cristobal Uauy, a group leader at the John Innes Centre and a co-author of the study, emphasized, “This research illustrates the significance of international collaboration and the importance of sharing data and seeds among nations; by pooling our resources and expertise across various institutions and borders, we can achieve remarkable outcomes.”

The research conducted by the Open Wild Wheat Consortium (OWWC) reveals that the success of bread wheat originates from the genetic variety of a wild grass known as Aegilops tauschii.

Bread wheat is a hybrid derived from three different wild grasses, incorporating three genomes (A, B, and D) within a single complex plant.

Aegilops tauschii, which is often overlooked as just a weed, supplied the D-genome when it crossed with early cultivated pasta wheat in the Fertile Crescent about eight to eleven thousand years ago.

This serendipitous hybridization along the southern Caspian Sea initiated an agricultural upheaval. As farmers embraced this novel crop—characterized by its high gluten content that produces airy, elastic bread dough—bread wheat cultivation expanded rapidly across diverse climates and soils.

This swift geographical spread has intrigued wheat scientists. Since there is no wild counterpart to bread wheat, and the hybridization that introduced the new D genome resulted in a genetic bottleneck, bread wheat exhibits significantly reduced genetic diversity compared to surrounding wild grasses.

This bottleneck effect, coupled with the inbreeding nature of wheat—meaning it primarily self-pollinates—would imply that bread wheat might struggle to thrive outside its Fertile Crescent origins. So how did it become a widespread crop across the region?

To address this mystery, the international team compiled a diversity panel consisting of 493 unique samples from Aegilops tauschii, spanning from northwestern Turkey to eastern China.

From this collection, they selected 46 samples that illustrated the traits and genetic diversity of the species, which they used to create a Pangenome, an advanced genetic map of Aegilops tauschii.

Using this genetic map, they examined 80,000 local bread wheat varieties—known as landraces—kept at CIMMYT and gathered from different parts of the globe.

The analysis revealed that approximately 75% of the D-genome in bread wheat descends from the L2 lineage of Aegilops tauschii, linked to the southern Caspian Sea. The other 25% of its genetic makeup comes from various lineages distributed throughout its range.

“This 25% genetic contribution from other lineages has played a crucial role in the success of bread wheat,” stated Professor Simon Krattinger, the leading author of the study.

“Without the genetic variety from this diverse lineage, our consumption of bread would likely be far less than it is today. Otherwise, bread wheat would probably only be a regional crop—significant to the Middle East, but I doubt it would have gained global prominence without this adaptability.”

A previous OWWC study highlighted a unique lineage of Aegilops tauschii found only in modern-day Georgia in the Caucasus, situated 500 kilometers from the Fertile Crescent. This lineage (L3) is significant for contributing the best-known gene for dough quality to bread wheat.

The researchers hypothesized that if this lineage represented an ancient gene input—similar to a Neanderthal footprint in the human genome—they would discover landraces in CIMMYT collections with a higher proportion of it.

Data analyses demonstrated that CIMMYT wheat landraces from the Georgian area contained 7% L3 gene segments, which is seven times higher than those found in landraces from the Fertile Crescent.

“We utilized the L3 tauschii accessions as a model to investigate the hybridizations across 80,000 landraces of bread wheat,” Professor Krattinger added.

“The findings nicely illustrate a scenario where bread wheat originated in the southern Caspian, and as it migrated and expanded agriculturally, it reached Georgia, where hybridizations with the unique and regionally limited L3 accessions introduced new genetic material.”

“This is one of the novel elements of our study, confirming that our new resources enable us to track these historic genetic contributions in bread wheat.”

Besides shedding light on this ancient biological question, the new open-source Pangenome and germplasm of Aegilops tauschii made available by the OWWC are currently being used by global researchers and breeders to identify new disease-resistant genes that will protect wheat crops from persistent agricultural challenges like wheat rust. They can also look for climate-resilient genes within this wild grass species to integrate into premium wheat varieties.

Collaborative efforts between researchers at the John Innes Centre and KAUST employed bioinformatics to trace the DNA contributions to bread wheat from the L3 lineage of Aegilops tauschii.

Professor Uauy concluded, “This study underscores the significance of preserving genetic resources, such as those maintained by the BBSRC-funded Germplasm Resources Unit at the John Innes Centre, which safeguards historic collections of wild grasses that can be utilized to incorporate valuable traits like disease and pest resistance into modern wheat.”