TY - JOUR

T1 - Direct regulation of phytoene synthase gene expression and carotenoid biosynthesis by phytochrome-interacting factors

AU - Toledo-Ortiz, Gabriela

AU - Huq, Enamul

AU - Rodríguez-Concepción, Manuel

PY - 2010/6/22

Y1 - 2010/6/22

N2 - Carotenoids are key for plants to optimize carbon fixing using the energy of sunlight. They contribute to light harvesting but also channel energy away from chlorophylls to protect the photosynthetic apparatus from excess light. Phytochrome-mediated light signals are major cues regulating carotenoid biosynthesis in plants, but we still lack fundamental knowledge on the components of this signaling pathway. Here we show that phytochrome-interacting factor 1 (PIF1) and other transcription factors of the phytochrome-interacting factor (PIF) family down-regulate the accumulation of carotenoids by specifically repressing the gene encoding phytoene synthase (PSY), the main rate-determining enzyme of the pathway. Both in vitro and in vivo evidence demonstrate that PIF1 directly binds to the promoter of the PSY gene, and that this binding results in repression of PSY expression. Light-triggered degradation of PIFs after interaction with photoactivated phytochromes during deetiolation results in a rapid derepression of PSY gene expression and a burst in the production of carotenoids in coordination with chlorophyll biosynthesis and chloroplast development for an optimal transition to photosynthetic metabolism. Our results also suggest a role for PIF1 and other PIFs in transducing light signals to regulate PSY gene expression and carotenoid accumulation during daily cycles of light and dark in mature plants.

AB - Carotenoids are key for plants to optimize carbon fixing using the energy of sunlight. They contribute to light harvesting but also channel energy away from chlorophylls to protect the photosynthetic apparatus from excess light. Phytochrome-mediated light signals are major cues regulating carotenoid biosynthesis in plants, but we still lack fundamental knowledge on the components of this signaling pathway. Here we show that phytochrome-interacting factor 1 (PIF1) and other transcription factors of the phytochrome-interacting factor (PIF) family down-regulate the accumulation of carotenoids by specifically repressing the gene encoding phytoene synthase (PSY), the main rate-determining enzyme of the pathway. Both in vitro and in vivo evidence demonstrate that PIF1 directly binds to the promoter of the PSY gene, and that this binding results in repression of PSY expression. Light-triggered degradation of PIFs after interaction with photoactivated phytochromes during deetiolation results in a rapid derepression of PSY gene expression and a burst in the production of carotenoids in coordination with chlorophyll biosynthesis and chloroplast development for an optimal transition to photosynthetic metabolism. Our results also suggest a role for PIF1 and other PIFs in transducing light signals to regulate PSY gene expression and carotenoid accumulation during daily cycles of light and dark in mature plants.

KW - Alkyl and Aryl Transferases

KW - Amino Acid Motifs

KW - Arabidopsis

KW - Arabidopsis Proteins

KW - Basic Helix-Loop-Helix Transcription Factors

KW - Carotenoids

KW - Chlorophyll

KW - Gene Expression Regulation, Enzymologic

KW - Gene Expression Regulation, Plant

KW - Geranylgeranyl-Diphosphate Geranylgeranyltransferase

KW - Light

KW - Models, Biological

KW - Phytochrome

KW - Promoter Regions, Genetic

KW - Seedlings

KW - Transcription, Genetic

U2 - 10.1073/pnas.0914428107

DO - 10.1073/pnas.0914428107

M3 - Journal article

C2 - 20534526

VL - 107

SP - 11626

EP - 11631

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 25

ER -