The Important Function of Mediator Complex in Controlling the Developmental Transitions in Plants

Developmental transitions in plants are tightly associated with changes in the transcriptional regulation of gene expression. One of the most important regulations is conferred by cofactors of RNA polymerase II including the mediator complex, a large complex with a modular organization. The mediator complex recruits transcription factors to bind to the specific sites of genes including protein-coding genes and non-coding RNA genes to promote or repress the transcription initiation and elongation using a protein-protein interaction module. Mediator complex subunits have been isolated and identified in plants and the function of most mediator subunits in whole life cycle plants have been revealed. Studies have shown that the Mediator complex is indispensable for the regulation of plant developmental transitions by recruiting age-, flowering-, or hormone-related transcription factors. Here, we first overviewed the Mediator subunits in plants, and then we summarized the specific Mediator subunits involved in developmental transitions, including vegetative phase change and floral transition. Finally, we proposed the future directions to further explore their roles in plants. The link between Mediator subunits and developmental transitions implies the necessity to explore targets of this complex as a potential application in developing high quality crop varieties.