Project name: SUPPRESSOR OF PHYTOCHROME B4#3 reduces the expression of PIF-activated genes and increases expression of growth repressors to regulate hypocotyl elongation in short days [ChIP-seq]

Description: SUPPRESSOR OF PHYTOCHROME B4-#3 (SOB3) is a member of the AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED (AHL) family of transcription factors that are involved in light-mediated growth in Arabidopsis thaliana, affecting processes such as hypocotyl elongation. The majority of the research on the AHLs has been conducted in continuous light. However, there are unique molecular events that promote growth in short days (SD) compared to constant light conditions. Therefore, we investigated how AHLs affect hypocotyl elongation in SD. Firstly, we observed that SOB3 inhibits hypocotyl growth in SD, similar to its effects in constant light. Next, we identified AHL-regulated genes in SD-grown seedlings by performing RNA-Seq in two sob3 mutants at different time points. Our transcriptomic data indicate that PHYTOCHROME INTERACTING FACTORS (PIFs) 4, 5, 7, and 8 along with PIF-target genes are repressed by AHLs. We also identified PIF target genes that are repressed and have not been previously described as AHL-regulated, including PRE1, PIL1, HFR1, CDF5, and XTR7. Interestingly, our RNA-seq data also suggest that AHLs activate the expression of growth repressors to control hypocotyl elongation, such as HY5 and IAA17. Notably, many growth-regulating and other genes affected by SOB3 were differentially regulated between these two sob3 mutants at the time points tested. Surprisingly, our ChIP-seq data indicate that SOB3 mostly binds to similar genes throughout the day. Collectively, these data indicate that SOB3 affects gene expression in a time point-specific manner irrespective of changes in binding throughout SD.Overall design: Genome-wide identification of SOB3 binding sites at different time points in Arabidopsis seedlings grown in short days

Data type: Epigenomics

Sample scope: Multiisolate

Relevance: ModelOrganism

Last updated: 2021-11-21