Changing MADS-Box Transcription Factor Protein–Protein Interactions as a Mechanism for Generating Floral Morphological Diversity

Abstract

Flowers display fantastic morphological diversity. Despite extreme variability in form, floral organ identity is specified by a core set of deeply conserved proteins—the floral MADS-box transcription factors. This indicates that while core gene function has been maintained, MADS-box transcription factors have evolved to regulate different downstream genes. 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.

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