Just One Copy

Abstract

Most model plant species have undergone at least one whole-genome duplication event relative to their nearest well-studied relative. The occurrence of a duplicated genome in the history of the species, even if not retained in the extant species, can confound estimates of molecular evolution. Wang et al. have investigated the relative rates of molecular evolution in a conserved syntenic sequence in members of the Solanaceae family (eggplant, pepper, petunia, potato, and tomato) that have undergone no genome-wide duplication events since they diverged, which from this study was estimated to have been ∼30 million years ago. Although some regions were duplicated within individual species, the authors were able to analyze genes and regions that have, more or less, been evolving as a single copy within the genome. They identified small-scale differences in the location of insertions and deletions, lineage-specific selection, gene content, order, and orientation, and estimated that approximately one-third of the examined regions is under selection and two-thirds of the sequences under selection are outside of genes and not associated with domestication.— LMZ