Phytochrome-interacting factors regulate seedling growth through ABA signaling.

There is a growing body of evidence that abscisic acid (ABA) and the phytochrome-interacting factor (PIF) family of transcription factors interact in light signaling, the regulation of plant growth development, and adaptation to environmental stimuli. In this study, we investigate the role that PIFs play in the regulation of ABA signaling in Arabidopsis thaliana seedlings grown under long-day conditions. We showed that PIFs positively regulate ABA signaling in post-germination seedling growth. We analyzed the DNA-binding sites for PIF3 and PIF5 by DNA-affinity purification sequencing (DAP-seq) genome-wide. The DAP-seq data showed that G-box motif is the direct binding site of PIF3 and PIF5, and a number of ABA responsive genes are potential targets of PIFs, including PYL3, PYL6, PYL12, SnRK2.2, CPK4, CPK6, ABI5, ABF3, and KIN1. Our results provide a basis for understanding the mechanism for PIFs in regulating ABA signal transduction.