The role of Arabidopsis mediator complex in plant defense

Plant diseases cause significant crop losses world-wide. Understanding the mechanisms of plant defense is imperative to designing better disease control strategies. Previously, our lab identified the MED21 subunit of Mediator complex as an important component of plant defense against necrotrophic fungi. Since then, MED8 and MED25 have also been recognized as instrumental in plant defense. Mediator is an evolutionarily conserved multi-subunit complex that regulates gene expression. In plants, fungi, and animals, Mediator functions as a coactivator or co-repressor through its interactions with sequence specific transcription factors and recruits RNA Polymerase II. In humans, subunits of Mediator are known targets of viruses, and mutations in some subunits lead to developmental disorders. We conducted a reverse genetics screen to identify additional subunits of Arabidopsis Mediator with functions in plant defense. Our screen identified subunits with a clear defense function. Further, Mediator subunits also control plant growth traits suggesting the interconnections between plant developmental processes and defense. Mediator subunits likely affect plant defense through their role in development which is discussed