GSE201389
COP1 SUPPRESSOR 6 promotes photomorphogenesis by repressing the transcription and activity of PIF4 and PIF5
Light signaling precisely controls the photomorphogenic development in plants. In this study, we report COP1 SUPPRESSOR 6 (CSU6) function as positive regulator of light signaling. Loss of CSU6 function largely rescued the cop1-6 constitutively photomorphogenic phenotype. The hypocotyl length of csu6 mutant seedlings was shorter in the dark, but longer than that of wide-type in the light. CSU6 not only associated with the promoter regions of PIF4 and PIF5 to inhibit their expression during the day, but also directly interacts with both PIF4 and PIF5 to repress their transcriptional activity. CSU6 negatively controls a large group of PIF4- and PIF5-mediated genes' expression. Mutations in PIF4 and/or PIF5 are epistatic to the loss of CSU6, suggesting that CSU6 acts upstream of PIF4 and PIF5. Taken together, CSU6 promotes photomorphogenesis by negatively regulating PIF4 and PIF5 transcription and biochemical activity. Overall design: Col-0 and csu6-2 mutant seedlings were grown in white light for 5 d. The samples were harvested and used to isolate total RNA with an RNeasy Plant Mini Kit (Qiagen).