Population genomics unravels the Holocene history of bread wheat and its relatives

Deep knowledge of crop biodiversity is essential to improving global food security. Despite bread wheat serving as a keystone crop worldwide, the population history of bread wheat and its relatives, both cultivated and wild, remains elusive. By analysing whole-genome sequences of 795 wheat accessions, we found that bread wheat originated from the southwest coast of the Caspian Sea and underwent a slow speciation process, lasting similar to 3,300 yr owing to persistent gene flow from its relatives. Soon after, bread wheat spread across Eurasia and reached Europe, South Asia and East Asia similar to 7,000 to similar to 5,000 yr ago, shaping a diversified but occasionally convergent adaptive landscape in novel environments. By contrast, the cultivated relatives of bread wheat experienced a population decline by similar to 82% over the past similar to 2,000 yr due to the food choice shift of humans. Further biogeographical modelling predicted a continued population shrinking of many bread wheat relatives in the coming decades because of their vulnerability to the changing climate. These findings will guide future efforts in protecting and utilizing wheat biodiversity to enhance global wheat production.

Automated summary

Through analyzing the whole-genome sequences of 795 wheat accessions, it was found that bread wheat originated from the southwest coast of the Caspian Sea and underwent a slow speciation process. It gradually spread across Eurasia in the past few thousand years and formed diversified adaptive landscapes in novel environments. In contrast, the cultivated relatives of bread wheat experienced a population decline due to human food choice shift, and many wheat relatives are predicted to continue shrinking in the future due to climate change. These findings will guide future efforts in protecting and utilizing wheat biodiversity to enhance global wheat production.