The HY5-PIF regulatory module coordinates light and temperature control of photosynthetic gene transcription

• Published in: PLoS genetics 2014-06, Vol.10 (6), p.e1004416-e1004416
• Main Authors: Toledo-Ortiz, Gabriela, Johansson, Henrik, Lee, Keun Pyo, Bou-Torrent, Jordi, Stewart, Kelly, Steel, Gavin, Rodríguez-Concepción, Manuel, Halliday, Karen J
• Format: Article
• Language: English
• Subjects: Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - biosynthesis; Arabidopsis Proteins - genetics; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - genetics; Biology and Life Sciences; Biosynthesis; Carotenoids - biosynthesis; Chlorophyll; Chlorophyll - biosynthesis; Chromophores; Circadian rhythm; G-Box Binding Factors - genetics; Gene expression; Gene Expression Regulation, Plant; Genetic aspects; Genetic transcription; Nuclear Proteins - genetics; Photoperiod; Photoreceptors; Photosynthesis; Photosynthesis - genetics; Physiological aspects; Phytochrome; Promoter Regions, Genetic; Proteins; Receptors, Peptide - biosynthesis; Seasons; Temperature; Transcription factors; Transcription, Genetic; Transcriptional Activation - genetics
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1004416

The ability to interpret daily and seasonal alterations in light and temperature signals is essential for plant survival. This is particularly important during seedling establishment when the phytochrome photoreceptors activate photosynthetic pigment production for photoautotrophic growth. Phytochromes accomplish this partly through the suppression of phytochrome interacting factors (PIFs), negative regulators of chlorophyll and carotenoid biosynthesis. While the bZIP transcription factor long hypocotyl 5 (HY5), a potent PIF antagonist, promotes photosynthetic pigment accumulation in response to light. Here we demonstrate that by directly targeting a common promoter cis-element (G-box), HY5 and PIFs form a dynamic activation-suppression transcriptional module responsive to light and temperature cues. This antagonistic regulatory module provides a simple, direct mechanism through which environmental change can redirect transcriptional control of genes required for photosynthesis and photoprotection. In the regulation of photopigment biosynthesis genes, HY5 and PIFs do not operate alone, but with the circadian clock. However, sudden changes in light or temperature conditions can trigger changes in HY5 and PIFs abundance that adjust the expression of common target genes to optimise photosynthetic performance and growth.