Mediator complex subunits in the regulation of phenylpropanoid biosynthesis ($)

The Mediator complex is a transcriptional co-regulator that is conserved across kingdoms. Several subunits have been identified through genetic approaches in Arabidopsis. Recessive loss-of-function mutants of MED5 subunits cause phenylpropanoid overaccumulation, but ef4-3, a semi-dominant mutation of a MED5 subunit leads to dwarfism and decreased phenylpropanoid accumulation. Other studies suggest that MED5 may function as a regulatory node for the phenylpropanoid pathway. To learn more about this function, Dolan et al. screened for suppressor mutants of ef4-3. All but one of the lines identified occur in Mediator subunits, providing “strong genetic data for the interdependency of multiple Mediator subunits in the establishment of the ref4-3 phenotype”. Their analysis also showed that the effects of ref4-3 on growth and phenylpropanoid metabolism can be separated genetically. (Summary by Mary Williams) Plant Cell 10.1105/tpc.17.00282