Abstract
As an evolutionarily conserved multi-protein complex, the Mediator complex modulates the association between transcription factors and RNA polymerase II to precisely regulate gene transcription. Although numerous studies have shown the diverse functions of Mediator complex in plant development, flowering, hormone signaling, and biotic stress response, its roles in the Abscisic acid (ABA) signaling pathway and abiotic stress response remain largely unclear. It has been recognized that the phytohormone, ABA, plays a predominant role in regulating plant adaption to various abiotic stresses as ABA can trigger extensive changes in the transcriptome to help the plants respond to environmental stimuli. Over the past decade, the Mediator complex has been revealed to play key roles in not only regulating the ABA signaling transduction but also in the abiotic stress responses. In this review, we will summarize current knowledge of the Mediator complex in regulating the plants’ response to ABA as well as to the abiotic stresses of cold, drought and high salinity. We will particularly emphasize the involvement of multi-functional subunits of MED25, MED18, MED16, and CDK8 in response to ABA and environmental perturbation. Additionally, we will discuss potential research directions available for further deciphering the role of Mediator complex in regulating ABA and other abiotic stress responses.
Highlights
The Mediator is an evolutionarily conserved eukaryotic multi-protein complex that has been recognized as a key regulator of plant growth and development, plant defense, and hormone signaling transduction [1–3]
The head module primarily associates with polymerase II (Pol II) to affect transcription whereas the tail module is believed to play a highly significant role as it interacts with gene-specific transcription factors (TFs)
Consistent with biochemical results, the over-expression of RAP2.6 resulted in hypersensitivity to Abscisic acid (ABA) and mannitol as well as higher expressions of several ABA-responsive genes. These findings indicated that RAP2.6 and CDK8 could finetune the transcription of ABA-responsive genes, especially those genes containing DRE/GCC-motifs
Summary
The Mediator is an evolutionarily conserved eukaryotic multi-protein complex that has been recognized as a key regulator of plant growth and development, plant defense, and hormone signaling transduction [1–3]. It regulates transcription through recruiting RNA polymerase II (Pol II) to specific gene promoters by linking transcription factors (TFs) bound at activators and repressors with the pre-initiation complex (PIC). Based on the classification from structural studies, the core Mediator is divided into the head, middle, and tail modules [7–9] Each of these modules is made up of different subunits that characterize the distinct function of each module on transcription [10]. We will discuss the most recently reported role of Mediator complex in three abiotic stresses of cold, high salinity, and drought
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
