the regulatory interactions between auxin response factors arfs and aux iaa repressors play a central role in auxin signal transduction yet the systems properties of this regulatory network are not well established we generated a steroid inducible arf5 monopteros mp transgenic background to survey the involvement of this factor in the transcriptional regulation of the entire aux iaa family in arabidopsis thaliana target genes of arf5 mp identified by this approach were confirmed by chromatin immunoprecipitation in vitro gel retardation assays and gene expression analyses our study shows that arf5 mp is indispensable for the correct regulation of nearly one half of all aux iaa genes and that these targets coincide with distinct subclades further genetic analyses demonstrate that the protein products of multiple aux iaa targets negatively feed back onto arf5 mp activity this work indicates that arf5 mp broadly influences the expression of the aux iaa gene family and suggests that such regulation involves the activation of specific subsets of redundantly functioning factors these groups of factors may then act together to control various processes within the plant through negative feedback on arf5 similar detailed analyses of other aux iaa arf regulatory modules will be required to fully understand how auxin signal transduction influences virtually every aspect of plant growth and development.