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United States Department of Agriculture

Agricultural Research Service

Title: PHYTOCHROME-INTERACTING FACTOR 1 IS A CRITICAL BHLH REGULATOR OF CHLOROPHYLL BIOSYNTHESIS

Author
item Huq, Enamul
item Al-sady, Bassem
item Hudson, Matthew
item Kim, Chanhong
item Apel, Klaus
item Quail, Peter

Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2004
Publication Date: 9/24/2004
Citation: Huq, E., Al-Sady, B., Hudson, M., Kim, C., Apel, K., Quail, P.H. 2004. PHYTOCHROME-INTERACTING FACTOR 1 is a Critical bHLH Regulator of Chlorophyll Biosynthesis. Science 305(5692):1937-1941.

Interpretive Summary: Plants must achieve a delicate balance between the light energy absorbed by chlorophyll and their capacity to channel that energy into productive photochemical reactions. We have identified a protein called PIF1 that controls chlorophyll synthesis and binds to phytochrome. Our data suggest a signaling pathway by which chlorophyll biosynthetic rates are tightly controlled during the critical initial emergence of seedlings from subterranean darkness into sunlight.

Technical Abstract: Photosynthetic organisms must achieve a delicate balance between the light energy absorbed by chlorophyll and their capacity to channel that energy into productive photochemical reactions. Release of excess absorbed energy in the cell can cause lethal photooxidative damage. We identified a basic helix-loop-helix (bHLH) transcription factor, designated PHYTOCHROME-INTERACTING FACTOR 1 (PIF1), that negatively regulates chlorophyll biosynthesis. pif1 mutant seedlings accumulate excess free protochlorophyllide when grown in the dark, with consequent lethal bleaching upon exposure to light. PIF1 interacts specifically with the photoactivated conformer of phytochromes A and B, suggesting a signaling pathway by which chlorophyll biosynthetic rates are tightly controlled during the critical initial emergence of seedlings from subterranean darkness into sunlight.

Last Modified: 08/22/2017
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