AT1G09530 — Arabidopsis thaliana

Summary

AT1G09530 (PAP3/PIF3) in Arabidopsis thaliana encodes a phytochrome interacting factor 3, a basic helix-loop-helix (bHLH) transcription regulator with activator activity, phytochrome binding, and nuclear import signal receptor activity. PIF3 is associated with phototransduction, positive regulation of the phytochrome signaling pathway, plastid gene expression, tetrapyrrole anabolism, and regulation of morphogenesis. It localizes to the plastid-encoded plastid RNA polymerase complex, chloroplast nucleoid, nuclear ubiquitin ligase complex, and chromatin. Observed phenotypes include freezing tolerance and photoresponsiveness. The gene is linked to numerous agronomic traits including stem number, seedling height, leaf area index, drought recovery, chlorophyll ratio, far-red light sensitivity, and UV-A light sensitivity. Studies of related genes in other species connect the family to cold tolerance, lycopene content, fruit ripening, and ascorbic acid content.