Document Detail


Phytochromes inhibit hypocotyl negative gravitropism by regulating the development of endodermal amyloplasts through phytochrome-interacting factors.
MedLine Citation:
PMID:  21220341     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Phytochromes are red and far-red light photoreceptors that regulate various aspects of plant development. One of the less-understood roles of phytochromes is the inhibition of hypocotyl negative gravitropism, which refers to the loss of hypocotyl gravitropism and resulting random growth direction in red or far-red light. This light response allows seedlings to curve toward blue light after emergence from the soil and enhances seedling establishment in the presence of mulch. Phytochromes inhibit hypocotyl negative gravitropism by inhibiting four phytochrome-interacting factors (PIF1, PIF3, PIF4, PIF5), as shown by hypocotyl agravitropism of dark-grown pif1 pif3 pif4 pif5 quadruple mutants. We show that phytochromes inhibit negative gravitropism by converting starch-filled gravity-sensing endodermal amyloplasts to other plastids with chloroplastic or etioplastic features in red or far-red light, whereas PIFs promote negative gravitropism by inhibiting the conversion of endodermal amyloplasts to etioplasts in the dark. By analyzing transgenic plants expressing PIF1 with an endodermis-specific SCARECROW promoter, we further show that endodermal PIF1 is sufficient to inhibit the conversion of endodermal amyloplasts to etioplasts and hypocotyl negative gravitropism of the pif quadruple mutant in the dark. Although the functions of phytochromes in gravitropism and chloroplast development are normally considered distinct, our results indicate that these two functions are closely related.
Authors:
Keunhwa Kim; Jieun Shin; Sang-Hee Lee; Hee-Seok Kweon; Julin N Maloof; Giltsu Choi
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-01-10
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  108     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-26     Completed Date:  2011-04-26     Revised Date:  2011-08-01    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1729-34     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
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MeSH Terms
Descriptor/Qualifier:
Arabidopsis / genetics,  growth & development,  radiation effects
Arabidopsis Proteins / genetics,  physiology*
Basic Helix-Loop-Helix Transcription Factors / genetics,  physiology*
Chloroplasts / metabolism,  ultrastructure
Gene Expression Profiling
Gene Expression Regulation, Developmental / radiation effects
Gene Expression Regulation, Plant / radiation effects
Gravitropism / physiology*,  radiation effects
Hypocotyl / genetics,  growth & development*,  radiation effects
Microscopy, Electron, Transmission
Mutation
Phytochrome A / genetics,  physiology*
Phytochrome B / genetics,  physiology*
Plants, Genetically Modified
Plastids / metabolism,  ultrastructure
Seedling / genetics,  growth & development,  radiation effects
Chemical
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Basic Helix-Loop-Helix Transcription Factors; 0/PHYA protein, Arabidopsis; 0/PHYB protein, Arabidopsis; 0/PIF1 protein, Arabidopsis; 0/PIF3 protein, Arabidopsis; 0/PIF4 protein, Arabidopsis; 0/PIF5 protein, Arabidopsis; 0/Phytochrome A; 136250-22-1/Phytochrome B
Comments/Corrections

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