MADS and More: Transcription Factors That Shape the Plant

All major processes of life depend on differential gene expression, which is largely controlled by the activity of transcription factors (TFs). In plants many TFs are encoded by members of multigene families that expanded much more dramatically during land plant evolution than during the evolution of animals and fungi. Here we review typical features such as domain structure, DNA binding, and protein interactions of TFs from some families that have contributed to the development and evolution of plant-specific structures in especially important ways. Our survey includes the MADS-domain protein family involved in specifying meristem and organ identity; YABBY proteins controlling lamina outgrowth; TCP proteins controlling floral zygomorphy and apical dominance; and finally homeodomain proteins involved in stem-cell maintenance and many other processes. Common themes as well as interesting differences between these “molecular architects of plant body plans” will become apparent.