PIF1 is a novel Myc-related BHLH transcription factor that has transcriptional activation activity in the dark. It is a key negative regulator of phytochrome-mediated seed germination and acts By inhiBiting chlorophyll Biosynthesis, light-mediated suppression of hypocotyl elongation and far-red light-mediated suppression of seed germination, and promoting negative gravitropism in hypocotyls. It also negatively regulates GA3 oxidase expression.
