Mediator is a multi-protein complex,which includes at least 25 subunits,forming a link between gene-specific transcription factors and pre-initiation complex.Mediator serves crucial functions in both protein-coding genes and noncoding RNA genes,and plays important roles in plant development and resistance.The phenotypes of individual mediator complex subunit mutants are distinct from each other,suggesting that the deletion of one mediator subunit does not interfere with transcription in general,but instead alters the expression of specific target genes.Therefore,certain developmental process in plant is regulated by specific mediator subunit genes.The clarification of the functions for individual mediator subunits is vital for fully understanding the developmental course and stress response.In this review,we discussed the roles of mediator complex in plant development combined with the new reports about mediator,and dissected the expression profiles of mediator subunits,proposed the assumption and expectation for the future study of mediator in plants.