Wheat is one of the most successful crops to human civilization. It originated from a small core area of the Fertile Crescent. Within 10,000 years and has been transformed from a regional wild plant to the most widely grown crop in the world, playing an important role in feeding a hungry world and improving global food security. The genetic mechanism of the successful adaptation of wheat to both natural environments and human needs is unclear. Understanding the adaptive evolution of wheat is invaluable for wheat genetic study and breeding in a changing climate.
Recently, researchers led by Dr. LU Fei and Dr. JIAO Yuling from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences (CAS) performed whole-genome sequencing of 414 accessions from 25 subspecies of wheat relatives in the genus Triticum and Aegilops and constructed a genus-level genetic variation map of wheat (VMap 1.0).
They identified that composite gene introgression from wild populations of wheat contributed 4% to 32% of the wheat genome which increased the genetic diversity of wheat tremendously and made it highly adaptable to various environments worldwide.
In addition, convergent adaptation to human selection showed 2- to 16-fold enrichment relative to random expectation. A certain set of genes repeatedly underwent independent artificial selection during parallel selective events, which are the key to shaping important agronomic traits and maintaining stable yield of wheat under different environments.
Fig 1. The shift of genetic diversity of Triticum species and model of diversity recovery in bread wheat (Image by IGDB)
This is the first time to construct a genus-level whole-genome genetic variation map in all crops. The genetic variation map of the genus Triticum (VMap) will be very useful to wheat genetic study and breeding.
This study illustrates the value of increasing crop genetic diversity in addressing the threat from climate change and ensuring food security. Moreover, it highlights the important role of evolutionary constraints in shaping the adaptive landscape of bread wheat.
These results showed the genetic necessities of wheat as a global crop and provided new perspectives on transferring adaptive success across species for crop improvement.
This research was funded by the Strategic Priority Research Program of CAS, the National Natural Science Foundation of China and the China Postdoctoral Science Foundation.
