Scientists have developed a new method using transposable elements to trace the evolutionary history of complex plant genomes. The approach was tested on the cultivated strawberry and identified multiple ancient hybridization events that shaped its octoploid genome.
Researchers from the U.S. Department of Agriculture and partner institutions applied the technique to Fragaria × ananassa. They identified four distinct subgenomes and dated three sequential allopolyploidization events to roughly 3.1-4.2 million years ago, 1.9-3.1 million years ago, and 0.8-1.9 million years ago.
The findings support close links between two subgenomes and the species Fragaria vesca and Fragaria iinumae. They also challenge earlier models that suggested additional diploid progenitors and indicate that some contributors may be extinct or unsampled.
One senior author noted that the method treats transposable elements as evolutionary time stamps. This allows reconstruction of genome history without relying on known ancestral references.
The study was published in Horticulture Research and funded by a National Institute of Food and Agriculture grant. It offers a tool for analyzing other polyploid crops such as wheat and cotton.
