Ancient hybridizations among the ancestral genomes of bread wheat

Marcussen et al. (Kjetill Jakobsen and Lise Heier) in Science

Abstract

The allohexaploid bread wheat genome consists of three closely related subgenomes (A, B, and D), but a clear understanding of their phylogenetic history has been lacking. We used genome assemblies of bread wheat and five diploid relatives to analyze genome-wide samples of gene trees, as well as to estimate evolutionary relatedness and divergence times. We show that the A and B genomes diverged from a common ancestor ~7 million years ago and that these genomes gave rise to the D genome through homoploid hybrid speciation 1 to 2 million years later. Our findings imply that the present-day bread wheat genome is a product of multiple rounds of hybrid speciation (homoploid and polyploid) and lay the foundation for a new framework for understanding the wheat genome as a multilevel phylogenetic mosaic.

Published 18 July, 2014

Tags: Science Magazine
Published May 31, 2015 8:24 AM - Last modified May 31, 2015 8:24 AM