Mankind has been growing the grain einkorn for thousands of years. Breeding later gave rise to our modern bread wheat, which is more productive and easier to harvest – but it is less resilient to environmental challenges than its primordial relative. Researchers have now sequenced the genomes of wild and domesticated einkorn varieties. The results not only provide information about the evolutionary history of the grain, but could also help to reintroduce genes into bread wheat that make it more resistant to heat, drought and pests.
The grain einkorn (Triticum monococcum) was the first domesticated wheat species and played a central role in the emergence of agriculture and the Neolithic Revolution in the Fertile Crescent more than 10,000 years ago. Over the centuries, people selected variants of this grain that were as easy to thresh as possible and had large grains – our modern bread wheat was born. However, since the focus of breeding was on high yields and easy cultivation, the wheat lost its natural resistance to drought, heat and pests over time. On the other hand, in einkorn, which is still cultivated today but has been bred to a lesser extent, these characteristics have been retained.
Insights into evolutionary history
A team led by Hanin Ibrahim Ahmed from the King Abdullah University of Science and Technology in Saudi Arabia has now taken advantage of this. To unravel the mysteries of einkorn resilience, they sequenced the entire genome of wild and domesticated einkorn. “By understanding the genetic diversity and evolutionary history of einkorn, researchers can now exploit its potential for future breeding efforts and the development of more resilient and nutritious wheat varieties,” says Ahmed.
In addition, the 5.2 billion base pairs long einkorn genome provides unique insights into the evolution of the grain. Until now, it has been assumed that the evolution of wheat was a continuous process, in which the different types of wheat developed from a common origin, but then mixed only slightly. “However, our genome analyzes show that the history of wheat is much more complex and that there has been extensive mixing and lively gene flow between different wheat species,” reports Ahmed’s colleague Simon Krattinger. In the future, these clues could also help to reconstruct the migration movements of our ancestors, who brought their respective types of grain with them to new regions.
Robust for climate change
By comparing it with the already known genome of common wheat, the team found that einkorn has repeatedly crossed into cultivated wheat species over the course of evolutionary history. “It is likely that einkorn grew in close proximity to other agriculturally grown wheat varieties, leading to DNA mixing between the two closely related species,” explains Krattinger. According to the analysis, around one percent of the genome of modern bread wheat consists of crossed einkorn genes. It is possible that these einkorn genes have already helped bread wheat in the past to adapt to changing climatic conditions, so that the corresponding variants were able to assert themselves.
The researchers hope that einkorn genes could also help make bread wheat more resilient to the challenges of climate change in the future. With the help of modern, molecularly guided breeding methods, the researchers want to transfer useful genes from einkorn to bread wheat. They also plan to cross bread wheat genes into einkorn to ensure that the healthy and tasty ancient grain is easier to grow and harvest and can therefore be used on a larger scale.
Source: Hanin Ibrahim Ahmed (King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia) et al., Nature, doi: 10.1038/s41586-023-06389-7