How Wheat Bread Gave Rise to Civilization

A recent international study has shed light on how a simple wheat plant transformed the course of human history, becoming the foundation that sustains a global population of eight billion people today. This research, published in the journal Nature, reveals a critical event in the evolution of our civilization: the birth of bread.

Professor Brande Wulff, a wheat researcher at King Abdullah University of Science and Technology (KAUST) and one of the study’s lead authors, emphasized the significance of their findings, stating, Our discoveries illuminate an iconic moment in our civilization that created a new form of agriculture, allowing humans to settle and form societies. This research not only uncovers the origins of one of our most basic foods but also explains how this crop revolutionized the way we live.

The key to the success of bread wheat, according to research conducted by the Open Wild Wheat Consortium (OWWC), lies in the genetic diversity of a seemingly insignificant wild grass called Aegilops tauschii. This humble plant contributed the D genome to bread wheat when it crossed with pasta wheat cultivated in the Fertile Crescent between eight and eleven thousand years ago.

This accidental crossbreeding, which occurred along the southern shores of the Caspian Sea, sparked an unprecedented agricultural revolution. The new bread wheat, with its high gluten content that creates a more airy and elastic dough, quickly spread across a wide range of climates and soils. Farmers eagerly adopted this dynamic crop, marking the beginning of a new era in agriculture and human nutrition.

However, the rapid geographic expansion of bread wheat has puzzled researchers for a long time. Unlike its wild ancestors, bread wheat is a “man-made” species that emerged from a unique hybridization event. This origin created a genetic bottleneck, meaning the new species had much less genetic diversity compared to the surrounding wild grasses.

To solve this mystery, the international team assembled a diverse panel of 493 unique Aegilops tauschii accessions, covering its geographic range from northwest Turkey to eastern China. From this panel, they selected 46 accessions to create a pan-genome, a high-quality genetic map of Aegilops tauschii.

Using this map, the researchers analyzed 80,000 local varieties of bread wheat conserved by the International Maize and Wheat Improvement Center (CIMMYT) and collected from around the world. The results were surprising: about 75% of bread wheat’s D genome derives from the L2 lineage of Aegilops tauschii, originating from the southern Caspian Sea. The remaining 25% comes from other lineages across its range.

Professor Simon Krattinger, the study’s lead author, explained, This 25% influx of genetic material from other tauschii lineages has contributed to and defined the success of bread wheat. Without the genetic viability provided by this diversity, it is very likely we wouldn’t be consuming bread on the scale we do today.

Moreover, an earlier OWWC study revealed the existence of a distinct Aegilops tauschii lineage geographically restricted to present-day Georgia in the Caucasus region. This lineage (L3) provided bread wheat with a crucial gene for dough quality.

The new open-access pan-genome of Aegilops tauschii and the germplasm made available by the OWWC are already being used by researchers and breeders worldwide. These resources are helping to discover new disease-resistance genes that will protect wheat crops from ancient agricultural pests like wheat rust. Additionally, they can leverage this wild grass species to find climate-resilient genes that could be incorporated into elite wheat cultivars.

Professor Cristobal Uauy from the John Innes Centre, another author of the study, emphasized the importance of global collaboration in this research: This work exemplifies the importance of global collaboration and the exchange of data and seeds between countries; by combining resources and expertise across institutes and international borders, we can achieve much.