Mechanisms driving functional divergence of transcription factor paralogs

Transcription factors (TFs) are core components of the regulatory toolkits that control gene expression. The sophistication of these regulatory toolkits dramatically increased during Eukaryotic evolution, accomplished in part by the duplication of existing TFs and the subsequent repurposing of these new paralogs. This process, termed functional divergence, drove the evolution of increasingly elaborate programs of gene expression and, in turn, cellular and organismal complexity. Mechanisms generating functional divergence of TF paralogs are thus of significant interest. Here, we review the numerous mechanisms that can lead to divergence of TF paralogs, drawing on studies from across Eukaryota but with a special emphasis on the plant kingdom. We end by placing these mechanisms back into a broader evolutionary context.