Genome-wide identification of PIF1-binding sites and direct-target genes of PIF1 transcriptional regulation in skotomorphogenesis

Dark-grown seedlings exhibit skotomorphogenic development. Genetic and molecular evidence indicates that a quartet of Arabidopsis Phytochrome (phy)-Interacting bHLH Factors (PIF1, 3, 4 and 5) are critically necessary to maintaining this developmental state, and that light activation of phy induces a switch to photomorphogenic development by inducing rapid degradation of the PIFs. Here, using combined ChIP-seq and RNA-seq analyses, we have identified genes that are direct targets of PIF1 transcriptional regulation, and we provide evidence that the quartet collectively regulate these genes by shared, direct binding to the target promoters in promoting skotomorphogenesis. Overall design: Three biological replicates data of PIF1-binding sites were collected by comparing the parallel ChIP samples from Myc-epitope-tagged-PIF1 (P1M) overexpressing transgenic seedlings and the wild-type (WT) control.