Changing MADS-Box transcription factor protein-protein interactions as a mechanism for generating floral morphological diversity

Abstract

Synopsis Flowers display fantasticmorphological diversity.Despite extreme variability in form, floral organ identity is specified by a core set ofdeeply conserved proteins-The floralMADS-box transcriptionfactors.This indicates thatwhile core gene function has beenmaintained,MADS-box transcription factors have evolved to regulate different downstreamgenes. Thus, the evolution of gene regulation downstream of the MADS-box transcription factors is likely central to the evolution of floral form. Gene regulation is determined by the combination of transcriptional regulators present at a particular cis-regulatory element at a particular time. Therefore, the interactions between transcription factors can be of profound importance in determining patterns of gene regulation. Here, after a short primer on flowers and floral morphology, I discuss the centrality of protein-protein interactions to MADS-box transcription factor function, and review the evidence that the evolution of MADS-box protein-protein interactions is a key driver in the evolution of gene regulation downstream of the MADS-box genes.